INT J TUBERC LUNG DIS 18(6):655–662 Q 2014 The Union http://dx.doi.org/10.5588/ijtld.13.0516
Survey of tuberculosis drug resistance among Tibetan refugees in India F. Salvo,* K. Dorjee,† K. Dierberg,‡ W. Cronin,§ T. D. Sadutshang,† G. B. Migliori,¶ C. Rodrigues,# F. Trentini,** C. Di Serio,** R. Chaisson,‡ D. M. Cirillo* *Emerging Pathogens Unit, San Raffaele Scientific Institute, Milan, Italy; †Tibetan Delek Hospital, Central Tibetan Administration, Dharamsala, India; ‡Division of Infectious Diseases, Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, §Maryland Department of Health and Mental Hygiene, Baltimore, Maryland, USA; ¶WHO Collaborating Centre for TB and Lung Diseases, Fondazione S Maugeri, Care and Research Institute, Tradate, Italy; #Department of Microbiology, Parmanand Deepchand Hinduja Hospital and Medical Research Centre, Mumbai, India; **University Center for Statistics in the Biomedical Sciences, Universita` Vita-Salute San Raffaele, Milan, Italy SUMMARY S E T T I N G : Tuberculosis (TB) is a major health problem among Tibetans living in exile in India. Although drugresistant TB is considered common in clinical practice, precise data are lacking. O B J E C T I V E : To determine the proportion of drugresistant cases among new and previously treated Tibetan TB patients. D E S I G N : In a drug resistance survey in five Tibetan settlements in India, culture and drug susceptibility testing (DST) for first-line drugs were performed among all consecutive new and previously treated TB cases from April 2010 to September 2011. DST against kanamycin (KM), ethionamide, para-aminosalicylic acid and ofloxacin (OFX) was performed on multidrugresistant TB (MDR-TB) isolates. R E S U LT S : Of 307 patients enrolled in the study, 264 (193 new and 71 previously treated) were culture-
positive and had DST available. All patients tested for the human immunodeficiency virus (n ¼ 250) were negative. Among new TB cases, 14.5% had MDR-TB and 5.7% were isoniazid (INH) monoresistant. Among previously treated cases, 31.4% had MDR-TB and 12.7% were INH-monoresistant. Of the MDR-TB isolates, 28.6% of new and 26.1% of previously treated cases were OFX-resistant, while 7.1% of new cases and 8.7% of previously treated cases were KM-resistant. Three patients had extensively drug-resistant TB. C O N C L U S I O N S : MDR-TB is common in new and previously treated Tibetans in India, who also show additional complex resistance patterns. Of particular concern is the high percentage of MDR-TB strains resistant to OFX, KM or both. K E Y W O R D S : MDR-TB; drug resistance survey; tuberculosis in refugees; Tibetan refugees
THE INCREASING INCIDENCE of drug-resistant tuberculosis (TB) is a major challenge for the control of TB epidemics worldwide. Disease caused by strains of Mycobacterium tuberculosis resistant to isoniazid (INH) and rifampicin (RMP) (i.e., multidrug-resistant TB [MDR-TB]) is an increasingly common finding worldwide, and 84 countries have reported at least one case of extensively drug-resistant TB (XDR-TB, defined as MDR-TB plus resistance to a fluoroquinolone and at least one of three second-line injectable agents).1,2 The World Health Organization (WHO) has emphasised the importance of collecting precise data on the proportion of TB cases that are MDR- or XDR-TB through the implementation of continuous surveillance systems or periodic surveys in each
country. Despite recent efforts by the WHO and its partners, reliable data from more than 30% of countries are still unavailable due to the lack of human and financial resources to implement these studies, as well as insufficient laboratory capacity.1,3 Tibetan refugees first arrived in India in 1959, when thousands fled Tibet across the Himalayan mountains, following the fourteenth Dalai Lama into exile. Since then, many Tibetans have resettled in India during various waves of migration. The largest settlements are now located in the Indian States of Karnataka and Himachal Pradesh; however, Tibetan enclaves are located throughout India, including in Delhi, Mumbai and Bangalore. A 2009 demographic survey conducted by the Central Tibetan Administration (CTA) in India reported 94 203 Tibetans
Correspondence to: Fulvio Salvo, Emerging Pathogens Unit, San Raffaele Scientific Institute, via Olgettina 60, Milan 20132, Italy. Tel: (þ39) 022 643 5684. Fax: (þ39) 022 643 5183. e-mail: [email protected] Article submitted 22 August 2013. Final version accepted 14 January 2014.
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living in India.4 They are one of the most mobile populations in the world, as a high percentage migrate within India or abroad. More than 50% (n ¼ 50 433) of Tibetan refugees in India reside in congregate settings, such as boarding schools, monasteries and nunneries.4 The CTA Department of Health (CTA-DOH) oversees all Tibetan health centres and clinics throughout India. TB is one of the major causes of morbidity and mortality among Tibetans living in India. Very few studies have been published on the incidence of TB among Tibetans in exile. One study reported an overall TB incidence of 835 cases per 100 000 population between 1994 and 1996.5 Based on unpublished data from 2010, TB incidence was 431/ 100 000, which is substantially higher than the rate in India (181/100 000) in 2011 based on WHO estimates.1 The CTA-DOH has been working in close collaboration with the Revised National Tuberculosis Control Programme (RNTCP) of the Government of India and the WHO to improve the effectiveness of TB control among the Tibetan population (Appendix).* The CTA-DOH provides anti-tuberculosis treatment under directly observed therapy (DOT) to every Tibetan patient refugee in India, and all treatment regimens adhere to international recommendations. Treatment is provided free of charge or for a symbolic fee based on the patient’s income. Nevertheless, TB control in the Tibetan population in India faces many challenges, such as high rates of migration, use of different health care providers and residence in congregate living settings such as monasteries and schools. MDR-TB rates were thought to be high among Tibetan TB patients in India; however, before 2010 the diagnosis of TB was rarely confirmed by culture and drug susceptibility testing (DST). No systematic survey has been performed, and there are few published reports describing the high rate of MDRTB (7–19%) among Tibetans; most of these are immigrants to the United States and Canada.6–8 The main objective of the present study was to determine the proportion of drug-resistant pulmonary TB cases among new and previously treated Tibetan TB patients in India. Specifically, we assessed resistance to first-line drugs (INH, RMP, ethambutol [EMB], streptomycin [SM]), and to second-line drugs (kanamycin [KM], ofloxacin [OFX], ethionamide [ETH], para-amino salicylic acid [PAS]) among all MDR-TB cases. We also assessed the relationship between specific sociodemographic and behavioural risk factors and the presence of drugresistant TB. * The Appendix is available in the online version of this article, at http://www.ingentaconnect.com/content/iuatld/ijtld/2014/ 00000018/00000006/art00007
METHODS Study design The survey was designed to recruit through 100% sampling of TB suspects at the five main Tibetan TB centres. In the absence of available data, the study sample was calculated based on the estimated average annual number of new sputum smear-positive cases reported in 2007–2009. The sample size was established based on recommended principles.9 For a total expected number of 250 patients in 1 year with an expected frequency of 10% MDR-TB as a conservative estimate and an expected error of 61% at 95% confidence level, the size of the sample required was estimated to be 215 cases. This number was inflated to .300 to adjust for false sputum smear-positives, contamination and loss during transport. Study centres The five major health centres serving the Tibetan community in India under the CTA-DOH were selected for inclusion in the study. The main hospital and referral centre for all Tibetan TB patients in India is the Tibetan Delek Hospital in Dharamsala, Himachal Pradesh, a designated microscopy centre under the RNTCP and which served as the study headquarters. There were three study centres in the state of Karnataka (Tso-Jhe-Khangsar Hospital in Bylakuppe, Doeguling Tibetan Resettlement Hospital in Mundgod and Kunkyap Dophenling Hospital in Kollegal) and one in Uttarakhand (Dekyiling Settlement Hospital, Dehradun). Health centres in smaller settlements, monasteries and schools were instructed to refer TB patients to these main health centres for enrolment. The total population covered in the study was estimated to be 60 000. Patient enrolment All consecutive new sputum smear-positive TB patients who presented to the five study sites were enrolled from May 2010 to September 2011. Sputum smear-negative patients with strong clinical and radiological evidence of TB were enrolled in the study after discussion with the study coordinators (criteria for enrolment are provided in the Appendix). Medical staff interviewed each patient enrolled in the study, and sociodemographic information was recorded on living setting, country of birth, year of migration, comorbidities, chronic medications, history of smoking, alcohol or drug use. Voluntary human immunodeficiency virus (HIV) testing was offered to every new TB patient. Based on the interview and review of medical records, if available, each patient was classified as a new or previously treated case. New cases were defined as patients who had never been treated for TB or who had received treatment for ,30 days. Previously treated cases were defined as patients
TB DRS among Tibetan refugees
who had received anti-tuberculosis treatment for .30 days. For previously treated cases, the outcome and other details about previous TB episode(s) were recorded, if available. Patients with extra-pulmonary TB, including pleural TB, were ineligible for the study unless they also had a positive sputum smear at diagnosis. Patients were suitable for enrolment only once: patients relapsing during the study period were not included again. Laboratory methods An early-morning sputum sample was collected from each patient after enrolment. The sample was refrigerated at 48C for a maximum of 2 days and transported to the Mycobacteriology Laboratory, Paramchand Deepchand Hinduja National Hospital and Medical Research Centre, Mumbai, India, for culture and DST. Culture was performed using liquid medium (BACTECe MGITe 960 culture; BD, Franklin Lakes, NJ, USA). Isolates from positive cultures were confirmed as Mycobacterium tuberculosis complex using the p-nitrobenzoic acid assay and tested for susceptibility to first-line drugs (INH, RMP, EMB, SM) using the BACTECe MGITe 960 SIRE Kit (BD).10 MDR-TB isolates were then tested for susceptibility to second-line drugs (KM 2.5 lg/ml, OFX 2.0 lg/ml, ETH 5.0 lg/ml, PAS 4.0 lg/ml) per international standards.11
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A binary logistic regression model was adopted to estimate whether covariates were associated with MDR-TB. Odds ratios (ORs) were computed with 95% confidence intervals (CIs) and v2 test-related P values. We also considered several stratifications to avoid confounding issues. The Fisher’s exact test was used whenever needed due to reduced sample size. We also investigated the impact of several covariates (qualitative and quantitative) on the probability of having MDR-TB through a multiple logistic regression model. Variables were selected through a stepwise regression with backward selection. We also studied interactions between variables, such as sex and living setting; however, none were found to be significant (Appendix).
RESULTS
Ethical considerations The study protocol was approved by the CTA-DOH. Verbal consent and consent for HIV testing was obtained from each patient before enrolment. All suspected TB patients referred to the study centres for diagnosis were offered mycobacterial culture with DST at no cost, irrespective of ethnicity. However, only Tibetan patients were included in the data analysis. Culture and DST results were forwarded to the diagnostic centre of each patient and used to guide treatment decisions. Data collected during patient interviews only included information routinely recorded on TB treatment cards.
Patient characteristics A total of 307 consecutive patients were recruited from April 2010 to September 2011; 37 (12%) specimens were culture-negative for mycobacteria, 269 patients (88%) were culture-positive for M. tuberculosis and one patient had non-tuberculous mycobacteria. Four patients with positive cultures were excluded from the analysis, as they were not of Tibetan ethnicity and were not living in the Tibetan community. One culture-positive specimen failed to grow during DST. DST results were available for analysis for 264 patients. Of these, 193 (73%) were new and 71 (27%) were previously treated cases. The majority of the patients were male (73.9%); the mean age was 29.4 years (616.5; median 24); 58% were born in India, 39.8% in Tibet, 1.5% in Nepal and ,1% in Bhutan. For those born in Tibet, Nepal and Bhutan, the mean duration of stay in India was 20 years. At the time of enrolment, 58.7% of the patients were residing in congregate living settings (such as schools, monasteries and hostels), whereas 41.3% were living in private households. All 250 patients tested for HIV were negative. Results were not available for 13 patients. One patient refused the test. Socio-demographic characteristics are summarised in Table 1.
Data collection and statistical analysis All study forms and laboratory reports were sent to the Tibetan Delek Hospital, where data were entered into an Excel database (MicrosoftQ Excel 2010, Redmond, WA, USA). Analyses were performed using R statistical software, version 2.15.2 (R Foundation for Statistical Computing, Vienna, Austria). For the preliminary analysis, we used contingency tables to explore relationships between binary variables. The association between MDR-TB and variables such as sex, age, living setting, country of birth and previous treatment was examined using the v2 test at P , 0.05 level of significance.
Drug resistance The prevalence of resistance to any first-line drug (INH, RMP, EMB, SM) was 21.8% in new cases and 47.9% in previously treated cases. Among new TB cases, 14.5% were resistant to both INH and RMP (i.e., MDR-TB) and 5.7% had isolates resistant to INH (6 EMB and/or SM) but not to RMP. Among previously treated patients, 32.4% had MDR-TB strains, and 12.7% were resistant to INH (6 to EMB and/or SM) but not to RMP. RMP monoresistance was not detected in either group. First-line DST results drugs are summarised in Table 2. In the MDR-TB subgroup, 97.9% of patients were
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Table 1
Sociodemographic characteristics of enrolled patients by study centre Overall (n ¼ 264) n (%)
Tibetan Delek Hospital, Dharamsala (n ¼ 135) n (%)
Sex Male Female
195 (73.9) 69 (26.1)
96 (71.1) 39 (28.9)
Age, years Mean (median)
29.4 (24)
28 (24)
Age group, years ,20 20–39 40–59 760
73 147 21 23
39 78 8 10
Living setting Monastery, school or hostel Private house
155 (58.7) 109 (41.3)
91 (67.4) 44 (32.6)
Country of birth Tibet India Nepal Bhutan
105 153 4 2
62 68 4 1
Years in India (for those born abroad) Mean (median) Anti-tuberculosis treatment in the past Never received treatment (new patient) Previously treated Drug resistance Non-MDR-TB MDR-TB
(27.7) (55.7) (8.0) (8.7)
Bylakuppe (n ¼ 47) n (%)
Mundgod (n ¼ 53) n (%)
Deckyiling (n ¼ 22) n (%)
35 (74.5) 12 (25.5)
46 (86.8) 7 (13.2)
12 (54.5) 10 (45.5)
30.5 (27)
1 3 1 2
23 (48.9) 24 (51.1)
28 (52.8) 25 (47.2)
13 (59.1) 9 (40.9)
0 7 (100)
10 (21.3) 37 (78.7) 0 0
22 (41.5) 30 (56.6) 0 1 (1.9)
8 (36.4) 14 (63.6) 0 0
3 (42.9) 4 (57.1) 0 0
17 (14)
20 (16)
28 (23)
12 (12)
193 (73.1) 71 (26.9)
97 (71.9) 38 (28.1)
30 (63.8) 17 (36.2)
43 (81.1) 10 (18.9)
18 (81.8) 4 (18.2)
5 (71.4) 2 (28.6)
213 (80.7) 51 (19.3)
113 (83.7) 22 (16.3)
35 (74.5) 12 (25.5)
46 (86.8) 7 (13.2)
14 (63.6) 8 (36.4)
5 (71.4) 2 (28.6)
(45.9) (50.4) (3.0) (0.7)
(14.9) (63.8) (14.9) (6.4)
16 26 3 8
43.4 (25)
10 (45.5) 10 (45.5) 2 (9.1) 0
20 (14)
7 30 7 3
23.6 (20)
6 (85.7) 1 (14.3)
(30.2) (49.1) (5.7) (15.1)
(39.8) (58.0) (1.5) (0.8)
(28.9) (57.8) (5.9) (7.4)
32.3 (22)
Kollegal (n ¼ 7) n (%)
(14.3) (42.9) (14.3) (28.6)
53 (53)
MDR-TB ¼ multidrug-resistant tuberculosis.
resistant to at least one additional drug, and the mean number of drugs to which MDR-TB isolates were resistant was 5.1 (median 5). Pre-XDR-TB, defined as additional resistance to OFX or to KM but not both, was common: resistance to OFX (but not KM) was found in 28.6% of the new and 21.7% of the previously treated MDR-TB cases, and resistance to KM (but not OFX) in 7.1% of new cases and 8.7% of previously treated cases. Three patients (two new, one previously treated) had XDR-TB strains. The previously treated XDR-TB case was resistant to all eight tested drugs. Therefore, 42.9% of new and 34.8% of
previously treated MDR-TB patients had isolates resistant to OFX, KM or both. Resistance to ETH was a common finding among both new and previously treated MDR-TB patients, with the proportion of resistant isolates being 75% and 69.6%, respectively. PAS-resistant strains were less common, at 14.3% among new cases and 17.4% among previously treated cases. Second-line DST results are summarised in Table 3. Risk factor analysis The results of the univariate analysis of the
Table 2 Susceptibility and resistance to first-line anti-tuberculosis drugs
Susceptibility or resistance Susceptibility to all first-line drugs Resistance to first-line drugs Any first-line drug INH RMP EMB SM INH alone (6 EMB or SM) RMP alone (6 EMB or SM) Multidrug resistance
Patients with new TB (n ¼ 193) n (%)
Patients with previously treated TB (n ¼ 71) n (%)
151 (78.2)
37 (52.1)
42 39 28 23 35 11 0 28
(21.8) (20.2) (14.5) (11.9) (18.1) (5.7) (14.5)
34 34 23 18 26 9 0 23
(47.9) (47.9) (32.4) (25.4) (36.6) (12.7) (32.4)
Retreatment vs. new cases OR (95%CI)
3.3 3.6 3.35 3.2 3 3.3
(1.8–5.9) (2.0–6.4) (1.73–6.5) (1.6–6.5) (1.6–5.6) (1.3–8.6) NA 3.3 (1.7–6.5)
P value (v2)
,0.0001 ,0.0001 0.0002 0.001 0.0003 0.01 NA 0.0002
TB ¼ tuberculosis; OR ¼ odds ratio; CI ¼ confidence interval; INH ¼ isoniazid; RMP ¼ rifampicin; EMB ¼ ethambutol; SM ¼ streptomycin; NA ¼ not available.
TB DRS among Tibetan refugees
Table 3
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Susceptibility and resistance to second-line anti-tuberculosis drugs in MDR-TB patients New patients Previously treated with MDR-TB patients with MDR-TB (n ¼ 28) (n ¼ 23) n (% n (%)
Susceptibility or resistance Susceptibility to OFX and KM
16 (57.1
15 (65.2)
Resistance to second-line drugs OFX or KM (not XDR-TB) OFX but not KM KM but not OFX XDR-TB Ethionamide PAS
10 8 2 2 21 4
7 5 2 1 16 4
(35.7) (28.6) (7.1) (7.1) (75.0) (14.3)
(30.4) (21.7) (8.7) (4.3) (69.6) (17.4)
Retreatment vs. new cases OR (95%CI)
0.7 0.7 1 0.5 0.8 1
(0.2–2.5) (0.18–2.5) (0.1–8.6) (0.04–6.5) (0.3–2.2) (0.2–5.0)
P value*
0.8 0.7 1.0 1.0 0.8 1.0
* Fisher’s exact test. MDR-TB ¼ multidrug-resistant tuberculosis; OR ¼ odds ratio; CI ¼ confidence interval; OFX ¼ ofloxacin; KM ¼ kanamycin; XDR-TB ¼ extensively drug-resistant tuberculosis.
association between sociodemographic characteristics and MDR-TB and other drug-resistant forms of TB is shown in Table 4. A history of previous treatment for TB was significantly associated with MDR-TB (OR 2.8, 95%CI 1.1–5.3). In addition, female sex (OR 2.2, 95%CI 1.1–4.1) and country of birth other than Tibet (OR 2.0, 95%CI 1.0–3.9) were significantly associated with an increased risk of MDR-TB. In multivariate analysis, the odds of MDR-TB were significantly higher for females, for persons living in congregate settings and for patients with a history of TB. Moreover, the odds of MDRTB decreased with age. The multivariate analysis is summarised in Table 5. Table 4
DISCUSSION The most recent data from the United Nations High Commission for Refugees demonstrate that the number of refugees and internally displaced persons worldwide was approximately 25 million in 2013, with most originating from and/or seeking asylum in high TB burden countries.12 The high risk of TB in this population is probably related to the coexistence of various predisposing factors, such as malnutrition, acute stress, HIV infection and the increased transmission of TB in overcrowded and poor living conditions.13 During the first several years in India, Tibetans suffered from severe malnutrition and lived in
Risk factors for drug-resistant TB
Variable
Non-MDR-TB MDR-TB (n ¼ 213) (n ¼ 51) n (%) n (%)
MDR-TB þ resistance to OFX or KM and XDR-TB MDR- vs. non-MDR-TB* (n ¼ 20) OR (95%CI) P value n (%)
MDR-TB þ resistance to OFX or KM and XDR-TB vs. non-MDR-TB† OR (95%CI)
P value
0.062
Sex Male Female
164 (77.0) 49 (23.0)
31 (60.8) Reference 20 (39.2) 2.2 (1.1–4.1)
0.018
11 (55.0) 9 (45.0)
Reference 2.5 (1.0–6.35)
Age group. years ,20 20–39 40–59 760
61 114 16 22
12 33 5 1
0.3 0.4 0.14
5 (25.0) 14 (70.0) 1 (5.0) 0
0.8 (0.3–2.4) 2.0 (0.8–5.5) 0.6 (0.1–5.2) NA
Living settings Private house School, monastery, hostel
81 (38.0) 132 (62.0)
26 (51.0) 1.7 (0.9–3.1) 25 (49.0) Reference
0.09
10 (50.0) 10 (50.0)
Reference 0.6 (0.3–1.6)
0.16
Country of birth Tibet India, Nepal or Bhutan
91 (42.7) 122 (57.3)
14 (27.5) Reference 37 (72.5) 2.0 (1.0–3.9)
0.045
4 (20.0) 16 (80.0)
Reference 2.8 (0.9–8.7)
0.094
History of previous treatment Never received treatment Previously treated
165 (77.5) 48 (22.5)
28 (54.9) Reference 23 (45.1 2.8 (1.5–5.3)
0.001
12 (60.0) 8 (40.0)
Reference 1.9 (0.75–4.9)
0.19
0 30 (14.1) 22 (10.3)
0 NA 8 (15.7) 1.1 (1.5–2.6) 6 (11.8) 1.2 (0.4–3.0)
NA 0.94 0.96
0 1 (5.0) 1 (5.0)
Risk factor HIV positivity Smoke Alcohol or illicit drugs
(28.6) (53.5) (7.5) (10.3)
(23.5) (64.7) (9.8) (2.0)
Reference 1.5 (0.7–3.0) 1.6 (0.5–5.2) 0.23 (0.03–1.9)
NA NA NA
1 0.24 1
NA NA NA
* v2 test. † Fisher’s exact test. TB ¼ tuberculosis; MDR-TB ¼ multidrug-resistant TB; OFX ¼ ofloxacin; KM ¼ kanamycin; XDR-TB ¼ extensively drug-resistant TB; OR ¼ odds ratio; CI ¼ confidence interval; NA ¼ not available; HIV ¼ human immunodeficiency virus.
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Table 5
Multivariate analysis
Variables Age Sex (male vs. female) Community (congregate vs. open) Patient (new vs. retreatment)
Estimate
Standard error
0.03 0.96 0.71 1.28
0.01 0.36 0.36 0.36
OR (95%CI) 0.74 0.38 0.49 0.28
(0.72–0.76) (0.19–0.77) (0.24–0.98) (0.14–0.56)
P value 0.034 ,0.001 0.045 ,0.001
OR ¼ odds ratio; CI ¼ confidence interval.
overcrowded and poor conditions, and TB could have spread in the population during this period. The results of our study demonstrate that MDR-TB is common in both new and previously treated Tibetan patients presenting to the main Tibetan health centres in India. The prevalence of MDR-TB is particularly alarming among new TB cases (14.5%), and is much higher than estimates for India (2.1%), China (5.7%), the WHO South-East Asia Region (SEAR) (2.1%) and globally (4.3%).1,14 Among previously treated TB patients, MDR-TB prevalence (32.4%) is again higher than that described in India (15%), China (25.6%), SEAR (16%) and globally (20%).1 The prevalence of fluoroquinolone resistance is higher than that reported from 67 other countries, with 35.7% among new MDR-TB cases and 26.1% among retreatment MDR-TB cases compared to 14.5% reported by the WHO. This is also higher than the median 12% prevalence reported in a recent meta-analysis of 26 studies by Falzon et al.15 However, the prevalence of KM resistance (14.2% in new and 13% in previously treated patients) among Tibetan TB patients is lower than the 21% prevalence reported in the above meta-analysis. Grouped together, pre-XDR and XDR-TB constitute 42.9% of new and 34.8% of previously treated MDR-TB cases. The selection of M. tuberculosis strains with resistance to multiple drugs in the Tibetan population in India has several possible explanations. First, both first- and second-line TB medications of unverifiable quality are still easily available on the open market in India.16,17 In the past, such medications were commonly used to treat Tibetan TB patients. Second, among patients treated in Tibetan clinics in the past, erratic funding resulted in intermittent disruption of drug supplies, leading to treatment interruptions. In addition, some patients stopped treatment due to the inability to pay for drugs from the private sector. Third, human resource constraints and insufficient infrastructure limited the capability of the programme to track highly mobile patients from one settlement to another to ensure continuity of treatment, often resulting in treatment interruption or default. Fourth, many Tibetan patients receive health care services from non-Department of Health facilities, including local private practitioners and monastery clinics. In these settings, standard international treatment guidelines are not followed consistently,
leading to an increase in the number of patients receiving inadequate management. These include prescribing fluoroquinolones for respiratory symptoms, inadequate numbers of anti-tuberculosis medications, inappropriate selection of drugs, inadequate dosage and insufficient treatment duration, particularly for MDR-TB. Fifth, the lack of easily accessible quality-assured laboratory facilities have greatly restricted the use of culture and DST to guide treatment and monitoring. Cultures were shipped to quality-assured laboratories only when financial resources were available and for the most difficult cases. Finally, drug-resistant strains selected by the aforementioned mechanisms have likely spread within the Tibetan community due to the increased risk of transmission between people living in congregate settings and the presence of language and cultural barriers that limit access to medical attention. It is also possible that Tibetans have a genetic susceptibility to TB, although there is currently no strong evidence to support this.18 The results of this study also highlight some important factors for diagnosis and treatment of TB in this population. The absence of RMP monoresistance confirms that a rapid molecular diagnostic test that detects RMP resistance, such as Xpertw MTB/ RIF (Cepheid, Sunnyvale, CA, USA), would be effective for rapid and accurate screening for MDRTB in this setting. 19 Rapid TB and MDR-TB diagnosis using the Xpert test has recently been initiated at the Tibetan Delek Hospital and two other Tibetan settlements, and preliminary data confirm that detection of RMP resistance is a highly accurate surrogate for MDR-TB.20 The pattern of resistance in the Tibetan population is complex, in terms of both the number of drugs to which isolates are susceptible and the high prevalence of resistance to essential second-line drugs such as fluoroquinolones and injectables, which are important for treatment success.15,21,22 The current WHO MDR-TB treatment guidelines recommend that patients with MDR-TB should be treated with a regimen containing a fluoroquinolone, an injectable and ETH; however, routine use of this regimen in Tibetan MDR-TB patients would result in a high proportion of patients receiving inadequate treatment. Rather than using a standardised MDR-TB regimen, our data strongly suggest that patients
TB DRS among Tibetan refugees
should receive individually tailored regimens based on culture and DST results. Phenotypic DST must still be considered mandatory if RMP resistance is detected using Xpert. As delays in obtaining DST results are inevitable, constructing initial empirical regimens for our patients is challenging. Interestingly, the high rates of TB and MDR-TB in the Tibetan population in India are similar to rates seen in parts of sub-Saharan Africa, where TB-HIV coinfection is common.1 However, none of the Tibetan patients enrolled was HIV-positive. HIV preventive activities should be further strengthened to avoid the negative impact that HIV coinfection would have on the spread of TB in this community. The history of previous treatment in this study is clearly associated with the risk of resistance to firstline drugs, including MDR-TB; however, the same association was not identified with resistance to second-line drugs. A possible explanation for this is that strains resistant to second-line drugs persisting in the community are more likely to be primarily acquired by new as well as previously treated patients, while resistance to first-line drugs is more likely to be generated in single patients by inadequate previous treatment. Although an association was observed between female sex and MDR-TB, there are no clear reasons for this, as among Tibetans in exile the gender issue is not relevant and women are usually not discriminated against. A possible confounding bias is the presence of few clusters of MDRTB in female patients residing in the same institutions. Over the past few years, the CTA-DOH has substantially improved standards for TB control, developed new guidelines based on current international recommendations and recruited expert professional human resources. These achievements were made possible through the support of and collaboration with the RNTCP, the WHO TB REACH programme and other international partners. These partnerships have helped to provide technical assistance and supervision to promote the rational use of anti-tuberculosis drugs, specifically second-line agents, and reduce the risk of developing more resistance.23 Particular attention to the use of existing drugs potentially useful for XDR-TB treatment (linezolid, meropenem and cotrimoxazole) and new drugs (bedaquiline, PA-824, delamanid) will be essential to ensure that these agents continue to be effective for treating MDR- and XDR-TB in this population.24–29 Our study has some limitations. First, a substantial number of Tibetan TB patient undergo diagnosis and treatment in private health care centres or in Indian RNCTP centres, and these cases were not enrolled in the study. Moreover, due to logistic and geographical barriers only the major five diagnostic centres could be included. Data recording on previous TB episode(s) were scattered, and often no precise information on
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previous treatment regimens and outcomes were available. In summary, our study highlights the need for direct interventions to reduce transmission of all TB strains, particularly in congregate living settings, by further strengthening infection control strategies and by promoting active case finding and precise contact tracing. It will also be critical to improve early diagnosis of MDR-TB and to provide effective treatment to all MDR-TB cases in order to prevent the development of additional resistance in this vulnerable population. Acknowledgements The authors are grateful to T Paldon and T Youdon for their precious field work and dedication to this project. This study was funded by the Italian Development Cooperation (Directorate General for Development Cooperation of the Italian Minister of Foreign Affairs) as part of a development cooperation project granted to AISPO (Italian Association for Solidarity among People) (‘Support to the TB control programme in the Tibetan Community in India’ project no AISPO/INDIA/8688). FS was the project director. DMC served as a scientific supervisor. KeD and KuD were actively involved in a project of active case finding implemented by Johns Hopkins University Centre for TB Research (JHU-CTR) in collaboration with the Centrol Tibetan Administration Department of Health (CTA-DOH) and the Tibetan Delek Hospital. KeD was the project manager and KuD the local project coordinator. This Academic Clinical Fellow project was supported by a TB REACH grant from the Stop TB Partnership, World Health Organization, Geneva, Switzerland. RC is the director of the JHUCTR.
References 1 World Health Organization. Global tuberculosis control: WHO report, 2012. WHO/HTM/TB/2012.6. Geneva, Switzerland: WHO, 2012. 2 Zignol M, van Gemert W, Falzon D, et al. Surveillance of antituberculosis drug resistance in the world: an updated analysis, 2007–2010. Bull World Health Organ 2012; 90: 111–119. 3 World Health Organization. Multidrug and extensively drugresistant TB (M/XDR-TB): 2010 Global Report on Surveillance and Response. WHO/HTM/TB/2010.3. Geneva, Switzerland: WHO, 2010. 4 Planning Commission, Central Tibetan Administration. Demographic Survey of Tibetans in exile – 2009. Dharamsala, India: CTA, 2010. 5 Nelson L J, Naik Y, Tsering K, Cegielski J P. Population-based risk factors for tuberculosis and adverse outcomes among Tibetan refugees in India, 1994–1996. Int J Tuberc Lung Dis 2005; 9: 1018–1026. 6 Truong D H, Hedemark L L, Mickman J K, Mosher L B, Dietrich S E, Lowry P W. Tuberculosis among Tibetan immigrants from India and Nepal in Minnesota, 1992–1995. JAMA 1997; 277: 735–738. 7 Marras T K, Wilson J, Wang E E, Avendano M, Yang J W. Tuberculosis among Tibetan refugee claimants in Toronto: 1998 to 2000. Chest 2003; 124: 915–921. 8 Lee Y A, Munsiff S S, Li J, Driver C R, Mathema B, Kreiswirth B N. Rising number of tuberculosis cases among Tibetans in New York City. J Immigr Health 2001; 3: 173–180. 9 World Health Organization. Guidelines for surveillance of drug resistance in tuberculosis. 4th ed. WHO/HTM/TB/2009.422. Geneva, Switzerland: WHO, 2009. 10 Siddiqi S H, Rusch-Gerdes S. MGIT procedure manual for ¨
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BACTEC 307 MGIT 960 TB System. Franklin Lakes, NJ, USA: BD, 2006. Rodrigues C, Jani J, Shenai P, Thakar P, Siddiqi S, Mehta A. Drug susceptibility testing of Mycobacterium tuberculosis against second-line drugs using the BACTEC MGIT 960 system. Int J Tuberc Lung Dis 2008; 12: 1449–1455. United Nation High Commission for Refugees. Populations of concern to UNHCR. Geneva, Switzerland: UNHCR, 2014. http://www.unhcr.org/50a9f81b27.html. Accessed March 2014 World Health Organization. Tuberculosis care and control in refugee and displaced populations: an interagency field manual. 2nd ed. WHO/HTM/TB/2007.377. Geneva, Switzerland: WHO, 2007. Zhao Y, Xu S, Wang L, et al. National survey of drug-resistant tuberculosis in China. N Engl J Med 2012; 366: 2161–2170. Falzon D, Gandhi N, Migliori G B, et al. Resistance to fluoroquinolones and second-line injectable drugs: impact on MDR-TB outcomes. Eur Respir J 2013; 42: 156–168. Olson S, English R A, Guenther R S, Claiborne A B; Forum on Drug Discovery, Development, and Translation; Board on Health Sciences Policy; Institute of Medicine. Facing the reality of drug-resistant tuberculosis in India: challenges and potential solutions: summary of a Joint Workshop by the Institute of Medicine, the Indian National Science Academy and the Indian Council of Medical Research. Washington, DC, USA: National Academies Press, 2012. Babu G R, Laxminarayan R. The unsurprising story of MDRTB resistance in India. Tuberculosis (Edinb) 2012; 92: 301– 306. Li D, Wang T, Song X, et al. Genetic study of two single nucleotide polymorphisms within corresponding microRNAs and susceptibility to tuberculosis in a Chinese Tibetan and Han population. Hum Immunol 2011; 72: 598–602. Weyer K, Mirzayev F, Migliori G B, et al. Rapid molecular TB diagnosis: evidence, policy making and global implementation of Xpert MTB/RIF. Eur Respir J 2013; 42: 252–271.
20 Salvo F, Sadutshang T D, Migliori G B, Zumla A, Cirillo D M. Xpert MTB/RIF test for tuberculosis. Lancet 2011; 378: 481– 482. 21 Migliori G B, Sotgiu G, Gandhi N R, et al. Drug resistance beyond XDR-TB: results from a large individual patient data meta-analysis. Eur Respir J 2013; 42: 169-79. 22 Ahuja S D, Ashkin D, Avendano M, et al. Multidrug-resistant pulmonary tuberculosis treatment regimens and patient outcomes: an individual patient data meta-analysis of 9,153 patients. PLOS MED 2012; 9: e1001300. 23 Migliori G B, Langendam M W, D’Ambrosio L, et al. Protecting the tuberculosis drug pipeline: stating the case for the rational use of fluoroquinolones. Eur Respir J 2012; 40: 814–822. 24 Gler M T, Skripconoka V, Sanchez-Garavito E, et al. Delamanid for multidrug-resistant pulmonary tuberculosis. N Engl J Med 2012; 366: 2151–2160. 25 Diacon A H, Dawson R, von Groote-Bidlingmaier F, et al. The 14-day bactericidal activity of combinations of PA-824, bedaquiline, pyrazinamide and moxifloxacin: the path to novel anti-tuberculosis treatment regimens. Lancet 2012; 380: 986– 993. 26 De Lorenzo S, Alffenaar J W, Sotgiu G, et al. Efficacy and safety of meropenem/clavunate added to linezolid containing regimens in the treatment of M/XDR-TB. Eur Respir J 2013; 41: 1386–1392. 27 Lee M, Lee J, Carroll M W, et al. Linezolid for treatment of chronic extensively drug-resistant tuberculosis. N Engl J Med 2012; 367: 1508–1518. 28 Sotgiu G, Centis R, D’Ambrosio L, et al. Efficacy, safety and tolerability of linezolid containing regimens in treating MDRTB and XDR-TB: systematic review and meta-analysis. Eur Respir J 2012; 40: 1430–1442. 29 Alsaad N, van Altena R, Pranger A D, et al. Evaluation of cotrimoxazole in treatment of multidrug-resistant tuberculosis. Eur Respir J 2013; 42: 504–512.
TB DRS among Tibetan refugees
APPENDIX Tibetan TB Control Programme The Tibetan Tuberculosis Control Programme is a collaborative initiative based at the Tibetan Delek Hospital in Himachal Pradesh State in northern India. It is run by Tibetan physicians and nurses and a large group of community health care workers. Tuberculosis (TB) services provided in other health centres in Tibetan refugee settlements, including Mundgod and Bylakuppe settlements in Karnataka State, are also part of the Tibetan TB Control Programme. The Tibetan Tuberculosis Programme Manual, developed in 2009 and based on the World Health Organization (WHO) and India’s national guidelines, provides structure and policy for TB control interventions. It has provided clinicians and other hospital staff with standardised procedures for diagnosis and treatment, infection control, surveillance, record keeping, patient and community education. The programme is jointly supported by the Central Tibetan Administration Department of Health (CTA-DOH), the Tibetan Delek Hospital, and three international non-governmental partners, namely the Johns Hopkins University Center for TB Research, Baltimore, MD, USA; the Friends of the Delek Hospital, Dharamsala, India; and the Italian Association for Solidarity among Peoples (AISPO), Milan, Italy. A steering committee of members representing each of the partners oversees the programme. The Tibetan TB Control Programme works in close collaboration with the India’s Revised National TB Control Programme (RNTCP), and all data on TB diagnosis and treatment outcome are currently reported to the RNTCP. In patients with suspected extensively drug-resistant (XDR-) and multidrugresistant TB (MDR-TB), sputum specimens are sent for sputum culture at the Hinduja Microbiology Laboratory in Mumbai, a WHO-approved laboratory facility. All patients who meet the criteria for treatment can receive anti-tuberculosis treatment at Delek Hospital, at CTA-DOH primary health centres and at local Indian government health clinics. Some Tibetan refugees also receive treatment through health facilities run by the RNTCP. First-line anti-tuberculosis drugs are provided free of cost by Delek Hospital, the CTA-DOH and the RNTCP, depending on where a patient seeks care. All Tibetan patients from any CTA-DOH clinic with suspected MDR- or XDR-TB are managed under the supervision of a panel of physicians experienced in the treatment of MDR- and XDRTB. The panel, based at Delek Hospital, regularly reviews all potential cases of MDR- and XDR-TB, provides advice and assistance to doctors in the field and makes recommendations for anti-tuberculosis treatment regimens. Once these recommendations
i
have been made, patients can receive treatment at Delek Hospital or another CTA-DOH facility with second-line medications purchased by the programme. A large network of community health providers helps to provide treatment to all the TB patients; every single dose of medication is currently provided under directly observed therapy. Criteria for enrolment of TB cases in the study 1 Any new sputum smear-positive TB case 2 A TB suspect with three sputum smear-negative samples with both clinical and radiological characteristics highly suggestive of TB, defined as: i Cough of .2 weeks plus any of the following: Unexplained weight loss Fever or night sweats Blood in sputum and ii Chest X-ray showing one of the following: Cavity/ies Fibro-nodular consolidation involving apical/ posterior segments of the upper lobes or superior segments of the lower lobes Statistical methods A preliminary analysis was carried out using contingency tables to explore relationships between binary variables. Association between MDR-TB group (Yes/ No) and variables such as sex, age, living settings, country of birth and previous treatment was evaluated using the v2 test at 0.05 level of significance. A binary logistic regression model was adopted to estimate whether and how covariates measured such as age, country of birth, previous history of TB, etc., affect the probability of developing MDR-TB. Odds ratios (ORs) were computed with their 95% confidence intervals (CIs) and v2 test-related P values. Analyses were prepared with R statistical software, version 2.15.2 (R Foundation for Statistical Computing, Vienna, Austria). We also considered several stratifications to avoid confounding issues, such as resistance vs. country of birth separately for female and male patients. Fisher’s exact test was used whenever needed in case of smaller sample size. After an explorative analysis, a multivariate analysis was performed. A multiple logistic regression model enabled us to investigate the joint impact on probability of being in the MDRTB group of a large set of covariates (both quantitative and qualitative) such as sex, age, country of birth (categorised as Tibet vs others [India, Nepal, Bhutan]), immigration to India (1 if immigrant, 0 otherwise), year of immigration, living setting (1 if patients live in a closed community, 0 otherwise) and history of previous treatment (1 old patient, 0 new patient). Variables were selected through stepwise
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regression with backward selection. We also investigated interactions between variables, such as sex and living setting, but none yielded statistically significant results. The final model selected four covariates as significant (at a significance level of 0.05): age, sex, community and history of previous treatment. The model selected to interpret the results is that in which age is treated as a continuous variable (Table). Using the coefficients obtained from the model with age as a continuous variable, we calculated the OR for the different variables and their CIs, and obtained the probability that the Mycobacterium tuberculosis strain is MDR-TB decreases by 1) about half in patients who live in enclosed communities
Table
Model selected to interpret results
Coefficients Community Age Sex New patient
OR 0.49 0.74 0.38 0.28
(enclosed vs open) (every 10 years more) (male vs. female) (new vs. retreatment cases)
95%CI 0.24–0.98 0.72–0.76 0.19–0.77 0.14–0.56
OR ¼ odds ratio; CI ¼ confidence interval.
compared to patients who live in open communities, 2) about three quarters in patients for every 10 years of age, 3) about 20% in male compared to female patients, and 4) about a quarter in patients with history of TB compared to patients with a previous history of TB.
TB DRS among Tibetan refugees
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RESUME
La tuberculose (TB) constitue l’un des principaux probl`emes de sant´e des Tib´etains en exil en Inde. Les cliniciens trouvent fr´equemment des TB pharmaco-r e´ sistantes, mais des donn e´ es pre´ cises manquaient. O B J E C T I F : D´eterminer la proportion de cas r´esistants parmi les patients tib´etains tuberculeux nouveaux et ceux d´eja` trait´es. S C H E M A : Nous avons r´ealis´e une enquˆete de r´esistance aux m´edicaments dans cinq collectivit´es tib´etaines en Inde. Une culture et un test de sensibilit e´ aux m´edicaments (DST) de premi`ere ligne ont e´ t´e r´ealis´es chez tous les patients nouveaux ou d´eja` trait´es entre avril 2010 et septembre 2011. Les DST pour la kanamycine (KM), l’´ethionamide, l’acide para-aminosalicylique et l’ofloxacine (OFX) ont e´ t´e r´ealis´es sur des isolats de TB multir´esistante (TB-MDR). R E S U LT A T S : De 307 patients enrol´ ˆ es, 264 ont eu une culture positive et un DST disponible ; 193 e´ taient des CONTEXTE :
nouveaux cas et 71 avaient d´eja` e´ t´e trait´es. Tous les patients test´es pour le virus de l’immunod´eficience humaine (n ¼ 250) e´ taient n´egatifs. Parmi les nouveaux cas, 14,5% e´ taient TB-MDR et 5,7% e´ taient r´esistants seulement a` l’isoniazide (INH). Parmi les cas d´eja` trait´es, 31,4% e´ taient TB-MDR et 12,7% e´ taient r´esistants a` l’INH seulement. Parmi les isolats TB-MDR, 28,6% des nouveaux cas et 26,1% des cas d´eja` trait´es e´ taient r´esistants a` l’OFX et 7,1% des nouveaux cas et 8,7% des cas d´eja` trait´es e´ taient r´esistants a` la KM. Trois patients avaient une TB ultrar´esistante. C O N C L U S I O N : La TB-MDR est fr´equente chez les nouveaux cas et les cas d´eja` trait´es parmi les Tib´etains en Inde. Les patients tibe´ tains TB-MDR pre´ sentaient d’autres profils de r e´ sistance complexes. Le pourcentage e´ lev´e de souches de TB-MDR r´esistantes a` l’OFX, a` la KM ou aux deux est particuli`erement pr´eoccupant.
RESUMEN M A R C O D E R E F E R E N C I A: La tuberculosis (TB) es uno de los principales problemas de salud en la comunidad tibetana en exilio en la India. Se acepta que la TB farmaco-resistente es frecuente en la pra´ctica cl´ınica, pero se carece de datos precisos. O B J E T I V O: Determinar la proporci on ´ de farmacorresistencia en los casos nuevos y los casos con antecedente de tratamiento en los pacientes tibetanos con diagnostico ´ TB. M E´ T O D O: Se llevo ´ a cabo una encuesta de farmacoresistencia en cinco asentamientos tibetanos en la India, con cultivo y prueba de sensibilidad a los medicamentos antituberculosos (DST) de primera l´ınea en todos los casos consecutivos de TB, nuevos y previamente tratados, que se diagnosticaron entre abril del 2010 y septiembre del 2011, adema´s de DST a kanamicina (KM), etionamida, a´ cido para-aminosalic´ılico y ofloxacino (OFX) a los aislados cl´ınicos TB multidrogorresistentes (TB-MDR). R E S U LT A D O S: Participaron en el estudio 307 pacientes y 264 obtuvieron cultivos positivos y contaban con DST.
De estos, 193 eran casos nuevos y 71 hab´ıan recibido tratamiento previamente. Todos los pacientes en quienes se practico´ la prueba diagnostica ´ del virus de la inmunodeficiencia humana obtuvieron un resultado negativo (n ¼ 250). En los casos nuevos se observo´ un 14,5% de TB-MDR y el 5,7% era monorresistente a isoniazida (INH). En los casos con antecedente de tratamiento se observo´ un 31,4% de casos TB-MDR y un 12,7% de monorresistencia a INH. En los aislados TB-MDR, el 28,6% de los casos nuevos y el 26,1% de los casos previamente tratados eran resistentes a OFX y el 7,1% de los casos nuevos y el 8,7% de los casos con tratamiento previo eran resistentes a KM. Tres pacientes presentaron TB extremadamente drogorresistente. C O N C L U S I O N E S: La TB-MDR es frecuente en los casos nuevos y en los casos con antecedente de tratamiento antituberculoso en la poblacion ´ tibetana de la India. Los pacientes provenientes del T´ıbet que presentan TBMDR exhiben otros tipos complejos de resistencias. Suscita una preocupacion ´ especial el alto porcentaje de cepas TB-MDR con resistencia a OFX, KM o a ambos.
Survey of tuberculosis drug resistance among Tibetan refugees in India F. Salvo,* K. Dorjee,† K. Dierberg,‡ W. Cronin,§ T. D. Sadutshang,† G. B. Migliori,¶ C. Rodrigues,# F. Trentini,** C. Di Serio,** R. Chaisson,‡ D. M. Cirillo* *Emerging Pathogens Unit, San Raffaele Scientific Institute, Milan, Italy; †Tibetan Delek Hospital, Central Tibetan Administration, Dharamsala, India; ‡Division of Infectious Diseases, Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, §Maryland Department of Health and Mental Hygiene, Baltimore, Maryland, USA; ¶WHO Collaborating Centre for TB and Lung Diseases, Fondazione S Maugeri, Care and Research Institute, Tradate, Italy; #Department of Microbiology, Parmanand Deepchand Hinduja Hospital and Medical Research Centre, Mumbai, India; **University Center for Statistics in the Biomedical Sciences, Universita` Vita-Salute San Raffaele, Milan, Italy SUMMARY S E T T I N G : Tuberculosis (TB) is a major health problem among Tibetans living in exile in India. Although drugresistant TB is considered common in clinical practice, precise data are lacking. O B J E C T I V E : To determine the proportion of drugresistant cases among new and previously treated Tibetan TB patients. D E S I G N : In a drug resistance survey in five Tibetan settlements in India, culture and drug susceptibility testing (DST) for first-line drugs were performed among all consecutive new and previously treated TB cases from April 2010 to September 2011. DST against kanamycin (KM), ethionamide, para-aminosalicylic acid and ofloxacin (OFX) was performed on multidrugresistant TB (MDR-TB) isolates. R E S U LT S : Of 307 patients enrolled in the study, 264 (193 new and 71 previously treated) were culture-
positive and had DST available. All patients tested for the human immunodeficiency virus (n ¼ 250) were negative. Among new TB cases, 14.5% had MDR-TB and 5.7% were isoniazid (INH) monoresistant. Among previously treated cases, 31.4% had MDR-TB and 12.7% were INH-monoresistant. Of the MDR-TB isolates, 28.6% of new and 26.1% of previously treated cases were OFX-resistant, while 7.1% of new cases and 8.7% of previously treated cases were KM-resistant. Three patients had extensively drug-resistant TB. C O N C L U S I O N S : MDR-TB is common in new and previously treated Tibetans in India, who also show additional complex resistance patterns. Of particular concern is the high percentage of MDR-TB strains resistant to OFX, KM or both. K E Y W O R D S : MDR-TB; drug resistance survey; tuberculosis in refugees; Tibetan refugees
THE INCREASING INCIDENCE of drug-resistant tuberculosis (TB) is a major challenge for the control of TB epidemics worldwide. Disease caused by strains of Mycobacterium tuberculosis resistant to isoniazid (INH) and rifampicin (RMP) (i.e., multidrug-resistant TB [MDR-TB]) is an increasingly common finding worldwide, and 84 countries have reported at least one case of extensively drug-resistant TB (XDR-TB, defined as MDR-TB plus resistance to a fluoroquinolone and at least one of three second-line injectable agents).1,2 The World Health Organization (WHO) has emphasised the importance of collecting precise data on the proportion of TB cases that are MDR- or XDR-TB through the implementation of continuous surveillance systems or periodic surveys in each
country. Despite recent efforts by the WHO and its partners, reliable data from more than 30% of countries are still unavailable due to the lack of human and financial resources to implement these studies, as well as insufficient laboratory capacity.1,3 Tibetan refugees first arrived in India in 1959, when thousands fled Tibet across the Himalayan mountains, following the fourteenth Dalai Lama into exile. Since then, many Tibetans have resettled in India during various waves of migration. The largest settlements are now located in the Indian States of Karnataka and Himachal Pradesh; however, Tibetan enclaves are located throughout India, including in Delhi, Mumbai and Bangalore. A 2009 demographic survey conducted by the Central Tibetan Administration (CTA) in India reported 94 203 Tibetans
Correspondence to: Fulvio Salvo, Emerging Pathogens Unit, San Raffaele Scientific Institute, via Olgettina 60, Milan 20132, Italy. Tel: (þ39) 022 643 5684. Fax: (þ39) 022 643 5183. e-mail: [email protected] Article submitted 22 August 2013. Final version accepted 14 January 2014.
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living in India.4 They are one of the most mobile populations in the world, as a high percentage migrate within India or abroad. More than 50% (n ¼ 50 433) of Tibetan refugees in India reside in congregate settings, such as boarding schools, monasteries and nunneries.4 The CTA Department of Health (CTA-DOH) oversees all Tibetan health centres and clinics throughout India. TB is one of the major causes of morbidity and mortality among Tibetans living in India. Very few studies have been published on the incidence of TB among Tibetans in exile. One study reported an overall TB incidence of 835 cases per 100 000 population between 1994 and 1996.5 Based on unpublished data from 2010, TB incidence was 431/ 100 000, which is substantially higher than the rate in India (181/100 000) in 2011 based on WHO estimates.1 The CTA-DOH has been working in close collaboration with the Revised National Tuberculosis Control Programme (RNTCP) of the Government of India and the WHO to improve the effectiveness of TB control among the Tibetan population (Appendix).* The CTA-DOH provides anti-tuberculosis treatment under directly observed therapy (DOT) to every Tibetan patient refugee in India, and all treatment regimens adhere to international recommendations. Treatment is provided free of charge or for a symbolic fee based on the patient’s income. Nevertheless, TB control in the Tibetan population in India faces many challenges, such as high rates of migration, use of different health care providers and residence in congregate living settings such as monasteries and schools. MDR-TB rates were thought to be high among Tibetan TB patients in India; however, before 2010 the diagnosis of TB was rarely confirmed by culture and drug susceptibility testing (DST). No systematic survey has been performed, and there are few published reports describing the high rate of MDRTB (7–19%) among Tibetans; most of these are immigrants to the United States and Canada.6–8 The main objective of the present study was to determine the proportion of drug-resistant pulmonary TB cases among new and previously treated Tibetan TB patients in India. Specifically, we assessed resistance to first-line drugs (INH, RMP, ethambutol [EMB], streptomycin [SM]), and to second-line drugs (kanamycin [KM], ofloxacin [OFX], ethionamide [ETH], para-amino salicylic acid [PAS]) among all MDR-TB cases. We also assessed the relationship between specific sociodemographic and behavioural risk factors and the presence of drugresistant TB. * The Appendix is available in the online version of this article, at http://www.ingentaconnect.com/content/iuatld/ijtld/2014/ 00000018/00000006/art00007
METHODS Study design The survey was designed to recruit through 100% sampling of TB suspects at the five main Tibetan TB centres. In the absence of available data, the study sample was calculated based on the estimated average annual number of new sputum smear-positive cases reported in 2007–2009. The sample size was established based on recommended principles.9 For a total expected number of 250 patients in 1 year with an expected frequency of 10% MDR-TB as a conservative estimate and an expected error of 61% at 95% confidence level, the size of the sample required was estimated to be 215 cases. This number was inflated to .300 to adjust for false sputum smear-positives, contamination and loss during transport. Study centres The five major health centres serving the Tibetan community in India under the CTA-DOH were selected for inclusion in the study. The main hospital and referral centre for all Tibetan TB patients in India is the Tibetan Delek Hospital in Dharamsala, Himachal Pradesh, a designated microscopy centre under the RNTCP and which served as the study headquarters. There were three study centres in the state of Karnataka (Tso-Jhe-Khangsar Hospital in Bylakuppe, Doeguling Tibetan Resettlement Hospital in Mundgod and Kunkyap Dophenling Hospital in Kollegal) and one in Uttarakhand (Dekyiling Settlement Hospital, Dehradun). Health centres in smaller settlements, monasteries and schools were instructed to refer TB patients to these main health centres for enrolment. The total population covered in the study was estimated to be 60 000. Patient enrolment All consecutive new sputum smear-positive TB patients who presented to the five study sites were enrolled from May 2010 to September 2011. Sputum smear-negative patients with strong clinical and radiological evidence of TB were enrolled in the study after discussion with the study coordinators (criteria for enrolment are provided in the Appendix). Medical staff interviewed each patient enrolled in the study, and sociodemographic information was recorded on living setting, country of birth, year of migration, comorbidities, chronic medications, history of smoking, alcohol or drug use. Voluntary human immunodeficiency virus (HIV) testing was offered to every new TB patient. Based on the interview and review of medical records, if available, each patient was classified as a new or previously treated case. New cases were defined as patients who had never been treated for TB or who had received treatment for ,30 days. Previously treated cases were defined as patients
TB DRS among Tibetan refugees
who had received anti-tuberculosis treatment for .30 days. For previously treated cases, the outcome and other details about previous TB episode(s) were recorded, if available. Patients with extra-pulmonary TB, including pleural TB, were ineligible for the study unless they also had a positive sputum smear at diagnosis. Patients were suitable for enrolment only once: patients relapsing during the study period were not included again. Laboratory methods An early-morning sputum sample was collected from each patient after enrolment. The sample was refrigerated at 48C for a maximum of 2 days and transported to the Mycobacteriology Laboratory, Paramchand Deepchand Hinduja National Hospital and Medical Research Centre, Mumbai, India, for culture and DST. Culture was performed using liquid medium (BACTECe MGITe 960 culture; BD, Franklin Lakes, NJ, USA). Isolates from positive cultures were confirmed as Mycobacterium tuberculosis complex using the p-nitrobenzoic acid assay and tested for susceptibility to first-line drugs (INH, RMP, EMB, SM) using the BACTECe MGITe 960 SIRE Kit (BD).10 MDR-TB isolates were then tested for susceptibility to second-line drugs (KM 2.5 lg/ml, OFX 2.0 lg/ml, ETH 5.0 lg/ml, PAS 4.0 lg/ml) per international standards.11
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A binary logistic regression model was adopted to estimate whether covariates were associated with MDR-TB. Odds ratios (ORs) were computed with 95% confidence intervals (CIs) and v2 test-related P values. We also considered several stratifications to avoid confounding issues. The Fisher’s exact test was used whenever needed due to reduced sample size. We also investigated the impact of several covariates (qualitative and quantitative) on the probability of having MDR-TB through a multiple logistic regression model. Variables were selected through a stepwise regression with backward selection. We also studied interactions between variables, such as sex and living setting; however, none were found to be significant (Appendix).
RESULTS
Ethical considerations The study protocol was approved by the CTA-DOH. Verbal consent and consent for HIV testing was obtained from each patient before enrolment. All suspected TB patients referred to the study centres for diagnosis were offered mycobacterial culture with DST at no cost, irrespective of ethnicity. However, only Tibetan patients were included in the data analysis. Culture and DST results were forwarded to the diagnostic centre of each patient and used to guide treatment decisions. Data collected during patient interviews only included information routinely recorded on TB treatment cards.
Patient characteristics A total of 307 consecutive patients were recruited from April 2010 to September 2011; 37 (12%) specimens were culture-negative for mycobacteria, 269 patients (88%) were culture-positive for M. tuberculosis and one patient had non-tuberculous mycobacteria. Four patients with positive cultures were excluded from the analysis, as they were not of Tibetan ethnicity and were not living in the Tibetan community. One culture-positive specimen failed to grow during DST. DST results were available for analysis for 264 patients. Of these, 193 (73%) were new and 71 (27%) were previously treated cases. The majority of the patients were male (73.9%); the mean age was 29.4 years (616.5; median 24); 58% were born in India, 39.8% in Tibet, 1.5% in Nepal and ,1% in Bhutan. For those born in Tibet, Nepal and Bhutan, the mean duration of stay in India was 20 years. At the time of enrolment, 58.7% of the patients were residing in congregate living settings (such as schools, monasteries and hostels), whereas 41.3% were living in private households. All 250 patients tested for HIV were negative. Results were not available for 13 patients. One patient refused the test. Socio-demographic characteristics are summarised in Table 1.
Data collection and statistical analysis All study forms and laboratory reports were sent to the Tibetan Delek Hospital, where data were entered into an Excel database (MicrosoftQ Excel 2010, Redmond, WA, USA). Analyses were performed using R statistical software, version 2.15.2 (R Foundation for Statistical Computing, Vienna, Austria). For the preliminary analysis, we used contingency tables to explore relationships between binary variables. The association between MDR-TB and variables such as sex, age, living setting, country of birth and previous treatment was examined using the v2 test at P , 0.05 level of significance.
Drug resistance The prevalence of resistance to any first-line drug (INH, RMP, EMB, SM) was 21.8% in new cases and 47.9% in previously treated cases. Among new TB cases, 14.5% were resistant to both INH and RMP (i.e., MDR-TB) and 5.7% had isolates resistant to INH (6 EMB and/or SM) but not to RMP. Among previously treated patients, 32.4% had MDR-TB strains, and 12.7% were resistant to INH (6 to EMB and/or SM) but not to RMP. RMP monoresistance was not detected in either group. First-line DST results drugs are summarised in Table 2. In the MDR-TB subgroup, 97.9% of patients were
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Table 1
Sociodemographic characteristics of enrolled patients by study centre Overall (n ¼ 264) n (%)
Tibetan Delek Hospital, Dharamsala (n ¼ 135) n (%)
Sex Male Female
195 (73.9) 69 (26.1)
96 (71.1) 39 (28.9)
Age, years Mean (median)
29.4 (24)
28 (24)
Age group, years ,20 20–39 40–59 760
73 147 21 23
39 78 8 10
Living setting Monastery, school or hostel Private house
155 (58.7) 109 (41.3)
91 (67.4) 44 (32.6)
Country of birth Tibet India Nepal Bhutan
105 153 4 2
62 68 4 1
Years in India (for those born abroad) Mean (median) Anti-tuberculosis treatment in the past Never received treatment (new patient) Previously treated Drug resistance Non-MDR-TB MDR-TB
(27.7) (55.7) (8.0) (8.7)
Bylakuppe (n ¼ 47) n (%)
Mundgod (n ¼ 53) n (%)
Deckyiling (n ¼ 22) n (%)
35 (74.5) 12 (25.5)
46 (86.8) 7 (13.2)
12 (54.5) 10 (45.5)
30.5 (27)
1 3 1 2
23 (48.9) 24 (51.1)
28 (52.8) 25 (47.2)
13 (59.1) 9 (40.9)
0 7 (100)
10 (21.3) 37 (78.7) 0 0
22 (41.5) 30 (56.6) 0 1 (1.9)
8 (36.4) 14 (63.6) 0 0
3 (42.9) 4 (57.1) 0 0
17 (14)
20 (16)
28 (23)
12 (12)
193 (73.1) 71 (26.9)
97 (71.9) 38 (28.1)
30 (63.8) 17 (36.2)
43 (81.1) 10 (18.9)
18 (81.8) 4 (18.2)
5 (71.4) 2 (28.6)
213 (80.7) 51 (19.3)
113 (83.7) 22 (16.3)
35 (74.5) 12 (25.5)
46 (86.8) 7 (13.2)
14 (63.6) 8 (36.4)
5 (71.4) 2 (28.6)
(45.9) (50.4) (3.0) (0.7)
(14.9) (63.8) (14.9) (6.4)
16 26 3 8
43.4 (25)
10 (45.5) 10 (45.5) 2 (9.1) 0
20 (14)
7 30 7 3
23.6 (20)
6 (85.7) 1 (14.3)
(30.2) (49.1) (5.7) (15.1)
(39.8) (58.0) (1.5) (0.8)
(28.9) (57.8) (5.9) (7.4)
32.3 (22)
Kollegal (n ¼ 7) n (%)
(14.3) (42.9) (14.3) (28.6)
53 (53)
MDR-TB ¼ multidrug-resistant tuberculosis.
resistant to at least one additional drug, and the mean number of drugs to which MDR-TB isolates were resistant was 5.1 (median 5). Pre-XDR-TB, defined as additional resistance to OFX or to KM but not both, was common: resistance to OFX (but not KM) was found in 28.6% of the new and 21.7% of the previously treated MDR-TB cases, and resistance to KM (but not OFX) in 7.1% of new cases and 8.7% of previously treated cases. Three patients (two new, one previously treated) had XDR-TB strains. The previously treated XDR-TB case was resistant to all eight tested drugs. Therefore, 42.9% of new and 34.8% of
previously treated MDR-TB patients had isolates resistant to OFX, KM or both. Resistance to ETH was a common finding among both new and previously treated MDR-TB patients, with the proportion of resistant isolates being 75% and 69.6%, respectively. PAS-resistant strains were less common, at 14.3% among new cases and 17.4% among previously treated cases. Second-line DST results are summarised in Table 3. Risk factor analysis The results of the univariate analysis of the
Table 2 Susceptibility and resistance to first-line anti-tuberculosis drugs
Susceptibility or resistance Susceptibility to all first-line drugs Resistance to first-line drugs Any first-line drug INH RMP EMB SM INH alone (6 EMB or SM) RMP alone (6 EMB or SM) Multidrug resistance
Patients with new TB (n ¼ 193) n (%)
Patients with previously treated TB (n ¼ 71) n (%)
151 (78.2)
37 (52.1)
42 39 28 23 35 11 0 28
(21.8) (20.2) (14.5) (11.9) (18.1) (5.7) (14.5)
34 34 23 18 26 9 0 23
(47.9) (47.9) (32.4) (25.4) (36.6) (12.7) (32.4)
Retreatment vs. new cases OR (95%CI)
3.3 3.6 3.35 3.2 3 3.3
(1.8–5.9) (2.0–6.4) (1.73–6.5) (1.6–6.5) (1.6–5.6) (1.3–8.6) NA 3.3 (1.7–6.5)
P value (v2)
,0.0001 ,0.0001 0.0002 0.001 0.0003 0.01 NA 0.0002
TB ¼ tuberculosis; OR ¼ odds ratio; CI ¼ confidence interval; INH ¼ isoniazid; RMP ¼ rifampicin; EMB ¼ ethambutol; SM ¼ streptomycin; NA ¼ not available.
TB DRS among Tibetan refugees
Table 3
659
Susceptibility and resistance to second-line anti-tuberculosis drugs in MDR-TB patients New patients Previously treated with MDR-TB patients with MDR-TB (n ¼ 28) (n ¼ 23) n (% n (%)
Susceptibility or resistance Susceptibility to OFX and KM
16 (57.1
15 (65.2)
Resistance to second-line drugs OFX or KM (not XDR-TB) OFX but not KM KM but not OFX XDR-TB Ethionamide PAS
10 8 2 2 21 4
7 5 2 1 16 4
(35.7) (28.6) (7.1) (7.1) (75.0) (14.3)
(30.4) (21.7) (8.7) (4.3) (69.6) (17.4)
Retreatment vs. new cases OR (95%CI)
0.7 0.7 1 0.5 0.8 1
(0.2–2.5) (0.18–2.5) (0.1–8.6) (0.04–6.5) (0.3–2.2) (0.2–5.0)
P value*
0.8 0.7 1.0 1.0 0.8 1.0
* Fisher’s exact test. MDR-TB ¼ multidrug-resistant tuberculosis; OR ¼ odds ratio; CI ¼ confidence interval; OFX ¼ ofloxacin; KM ¼ kanamycin; XDR-TB ¼ extensively drug-resistant tuberculosis.
association between sociodemographic characteristics and MDR-TB and other drug-resistant forms of TB is shown in Table 4. A history of previous treatment for TB was significantly associated with MDR-TB (OR 2.8, 95%CI 1.1–5.3). In addition, female sex (OR 2.2, 95%CI 1.1–4.1) and country of birth other than Tibet (OR 2.0, 95%CI 1.0–3.9) were significantly associated with an increased risk of MDR-TB. In multivariate analysis, the odds of MDR-TB were significantly higher for females, for persons living in congregate settings and for patients with a history of TB. Moreover, the odds of MDRTB decreased with age. The multivariate analysis is summarised in Table 5. Table 4
DISCUSSION The most recent data from the United Nations High Commission for Refugees demonstrate that the number of refugees and internally displaced persons worldwide was approximately 25 million in 2013, with most originating from and/or seeking asylum in high TB burden countries.12 The high risk of TB in this population is probably related to the coexistence of various predisposing factors, such as malnutrition, acute stress, HIV infection and the increased transmission of TB in overcrowded and poor living conditions.13 During the first several years in India, Tibetans suffered from severe malnutrition and lived in
Risk factors for drug-resistant TB
Variable
Non-MDR-TB MDR-TB (n ¼ 213) (n ¼ 51) n (%) n (%)
MDR-TB þ resistance to OFX or KM and XDR-TB MDR- vs. non-MDR-TB* (n ¼ 20) OR (95%CI) P value n (%)
MDR-TB þ resistance to OFX or KM and XDR-TB vs. non-MDR-TB† OR (95%CI)
P value
0.062
Sex Male Female
164 (77.0) 49 (23.0)
31 (60.8) Reference 20 (39.2) 2.2 (1.1–4.1)
0.018
11 (55.0) 9 (45.0)
Reference 2.5 (1.0–6.35)
Age group. years ,20 20–39 40–59 760
61 114 16 22
12 33 5 1
0.3 0.4 0.14
5 (25.0) 14 (70.0) 1 (5.0) 0
0.8 (0.3–2.4) 2.0 (0.8–5.5) 0.6 (0.1–5.2) NA
Living settings Private house School, monastery, hostel
81 (38.0) 132 (62.0)
26 (51.0) 1.7 (0.9–3.1) 25 (49.0) Reference
0.09
10 (50.0) 10 (50.0)
Reference 0.6 (0.3–1.6)
0.16
Country of birth Tibet India, Nepal or Bhutan
91 (42.7) 122 (57.3)
14 (27.5) Reference 37 (72.5) 2.0 (1.0–3.9)
0.045
4 (20.0) 16 (80.0)
Reference 2.8 (0.9–8.7)
0.094
History of previous treatment Never received treatment Previously treated
165 (77.5) 48 (22.5)
28 (54.9) Reference 23 (45.1 2.8 (1.5–5.3)
0.001
12 (60.0) 8 (40.0)
Reference 1.9 (0.75–4.9)
0.19
0 30 (14.1) 22 (10.3)
0 NA 8 (15.7) 1.1 (1.5–2.6) 6 (11.8) 1.2 (0.4–3.0)
NA 0.94 0.96
0 1 (5.0) 1 (5.0)
Risk factor HIV positivity Smoke Alcohol or illicit drugs
(28.6) (53.5) (7.5) (10.3)
(23.5) (64.7) (9.8) (2.0)
Reference 1.5 (0.7–3.0) 1.6 (0.5–5.2) 0.23 (0.03–1.9)
NA NA NA
1 0.24 1
NA NA NA
* v2 test. † Fisher’s exact test. TB ¼ tuberculosis; MDR-TB ¼ multidrug-resistant TB; OFX ¼ ofloxacin; KM ¼ kanamycin; XDR-TB ¼ extensively drug-resistant TB; OR ¼ odds ratio; CI ¼ confidence interval; NA ¼ not available; HIV ¼ human immunodeficiency virus.
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Table 5
Multivariate analysis
Variables Age Sex (male vs. female) Community (congregate vs. open) Patient (new vs. retreatment)
Estimate
Standard error
0.03 0.96 0.71 1.28
0.01 0.36 0.36 0.36
OR (95%CI) 0.74 0.38 0.49 0.28
(0.72–0.76) (0.19–0.77) (0.24–0.98) (0.14–0.56)
P value 0.034 ,0.001 0.045 ,0.001
OR ¼ odds ratio; CI ¼ confidence interval.
overcrowded and poor conditions, and TB could have spread in the population during this period. The results of our study demonstrate that MDR-TB is common in both new and previously treated Tibetan patients presenting to the main Tibetan health centres in India. The prevalence of MDR-TB is particularly alarming among new TB cases (14.5%), and is much higher than estimates for India (2.1%), China (5.7%), the WHO South-East Asia Region (SEAR) (2.1%) and globally (4.3%).1,14 Among previously treated TB patients, MDR-TB prevalence (32.4%) is again higher than that described in India (15%), China (25.6%), SEAR (16%) and globally (20%).1 The prevalence of fluoroquinolone resistance is higher than that reported from 67 other countries, with 35.7% among new MDR-TB cases and 26.1% among retreatment MDR-TB cases compared to 14.5% reported by the WHO. This is also higher than the median 12% prevalence reported in a recent meta-analysis of 26 studies by Falzon et al.15 However, the prevalence of KM resistance (14.2% in new and 13% in previously treated patients) among Tibetan TB patients is lower than the 21% prevalence reported in the above meta-analysis. Grouped together, pre-XDR and XDR-TB constitute 42.9% of new and 34.8% of previously treated MDR-TB cases. The selection of M. tuberculosis strains with resistance to multiple drugs in the Tibetan population in India has several possible explanations. First, both first- and second-line TB medications of unverifiable quality are still easily available on the open market in India.16,17 In the past, such medications were commonly used to treat Tibetan TB patients. Second, among patients treated in Tibetan clinics in the past, erratic funding resulted in intermittent disruption of drug supplies, leading to treatment interruptions. In addition, some patients stopped treatment due to the inability to pay for drugs from the private sector. Third, human resource constraints and insufficient infrastructure limited the capability of the programme to track highly mobile patients from one settlement to another to ensure continuity of treatment, often resulting in treatment interruption or default. Fourth, many Tibetan patients receive health care services from non-Department of Health facilities, including local private practitioners and monastery clinics. In these settings, standard international treatment guidelines are not followed consistently,
leading to an increase in the number of patients receiving inadequate management. These include prescribing fluoroquinolones for respiratory symptoms, inadequate numbers of anti-tuberculosis medications, inappropriate selection of drugs, inadequate dosage and insufficient treatment duration, particularly for MDR-TB. Fifth, the lack of easily accessible quality-assured laboratory facilities have greatly restricted the use of culture and DST to guide treatment and monitoring. Cultures were shipped to quality-assured laboratories only when financial resources were available and for the most difficult cases. Finally, drug-resistant strains selected by the aforementioned mechanisms have likely spread within the Tibetan community due to the increased risk of transmission between people living in congregate settings and the presence of language and cultural barriers that limit access to medical attention. It is also possible that Tibetans have a genetic susceptibility to TB, although there is currently no strong evidence to support this.18 The results of this study also highlight some important factors for diagnosis and treatment of TB in this population. The absence of RMP monoresistance confirms that a rapid molecular diagnostic test that detects RMP resistance, such as Xpertw MTB/ RIF (Cepheid, Sunnyvale, CA, USA), would be effective for rapid and accurate screening for MDRTB in this setting. 19 Rapid TB and MDR-TB diagnosis using the Xpert test has recently been initiated at the Tibetan Delek Hospital and two other Tibetan settlements, and preliminary data confirm that detection of RMP resistance is a highly accurate surrogate for MDR-TB.20 The pattern of resistance in the Tibetan population is complex, in terms of both the number of drugs to which isolates are susceptible and the high prevalence of resistance to essential second-line drugs such as fluoroquinolones and injectables, which are important for treatment success.15,21,22 The current WHO MDR-TB treatment guidelines recommend that patients with MDR-TB should be treated with a regimen containing a fluoroquinolone, an injectable and ETH; however, routine use of this regimen in Tibetan MDR-TB patients would result in a high proportion of patients receiving inadequate treatment. Rather than using a standardised MDR-TB regimen, our data strongly suggest that patients
TB DRS among Tibetan refugees
should receive individually tailored regimens based on culture and DST results. Phenotypic DST must still be considered mandatory if RMP resistance is detected using Xpert. As delays in obtaining DST results are inevitable, constructing initial empirical regimens for our patients is challenging. Interestingly, the high rates of TB and MDR-TB in the Tibetan population in India are similar to rates seen in parts of sub-Saharan Africa, where TB-HIV coinfection is common.1 However, none of the Tibetan patients enrolled was HIV-positive. HIV preventive activities should be further strengthened to avoid the negative impact that HIV coinfection would have on the spread of TB in this community. The history of previous treatment in this study is clearly associated with the risk of resistance to firstline drugs, including MDR-TB; however, the same association was not identified with resistance to second-line drugs. A possible explanation for this is that strains resistant to second-line drugs persisting in the community are more likely to be primarily acquired by new as well as previously treated patients, while resistance to first-line drugs is more likely to be generated in single patients by inadequate previous treatment. Although an association was observed between female sex and MDR-TB, there are no clear reasons for this, as among Tibetans in exile the gender issue is not relevant and women are usually not discriminated against. A possible confounding bias is the presence of few clusters of MDRTB in female patients residing in the same institutions. Over the past few years, the CTA-DOH has substantially improved standards for TB control, developed new guidelines based on current international recommendations and recruited expert professional human resources. These achievements were made possible through the support of and collaboration with the RNTCP, the WHO TB REACH programme and other international partners. These partnerships have helped to provide technical assistance and supervision to promote the rational use of anti-tuberculosis drugs, specifically second-line agents, and reduce the risk of developing more resistance.23 Particular attention to the use of existing drugs potentially useful for XDR-TB treatment (linezolid, meropenem and cotrimoxazole) and new drugs (bedaquiline, PA-824, delamanid) will be essential to ensure that these agents continue to be effective for treating MDR- and XDR-TB in this population.24–29 Our study has some limitations. First, a substantial number of Tibetan TB patient undergo diagnosis and treatment in private health care centres or in Indian RNCTP centres, and these cases were not enrolled in the study. Moreover, due to logistic and geographical barriers only the major five diagnostic centres could be included. Data recording on previous TB episode(s) were scattered, and often no precise information on
661
previous treatment regimens and outcomes were available. In summary, our study highlights the need for direct interventions to reduce transmission of all TB strains, particularly in congregate living settings, by further strengthening infection control strategies and by promoting active case finding and precise contact tracing. It will also be critical to improve early diagnosis of MDR-TB and to provide effective treatment to all MDR-TB cases in order to prevent the development of additional resistance in this vulnerable population. Acknowledgements The authors are grateful to T Paldon and T Youdon for their precious field work and dedication to this project. This study was funded by the Italian Development Cooperation (Directorate General for Development Cooperation of the Italian Minister of Foreign Affairs) as part of a development cooperation project granted to AISPO (Italian Association for Solidarity among People) (‘Support to the TB control programme in the Tibetan Community in India’ project no AISPO/INDIA/8688). FS was the project director. DMC served as a scientific supervisor. KeD and KuD were actively involved in a project of active case finding implemented by Johns Hopkins University Centre for TB Research (JHU-CTR) in collaboration with the Centrol Tibetan Administration Department of Health (CTA-DOH) and the Tibetan Delek Hospital. KeD was the project manager and KuD the local project coordinator. This Academic Clinical Fellow project was supported by a TB REACH grant from the Stop TB Partnership, World Health Organization, Geneva, Switzerland. RC is the director of the JHUCTR.
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TB DRS among Tibetan refugees
APPENDIX Tibetan TB Control Programme The Tibetan Tuberculosis Control Programme is a collaborative initiative based at the Tibetan Delek Hospital in Himachal Pradesh State in northern India. It is run by Tibetan physicians and nurses and a large group of community health care workers. Tuberculosis (TB) services provided in other health centres in Tibetan refugee settlements, including Mundgod and Bylakuppe settlements in Karnataka State, are also part of the Tibetan TB Control Programme. The Tibetan Tuberculosis Programme Manual, developed in 2009 and based on the World Health Organization (WHO) and India’s national guidelines, provides structure and policy for TB control interventions. It has provided clinicians and other hospital staff with standardised procedures for diagnosis and treatment, infection control, surveillance, record keeping, patient and community education. The programme is jointly supported by the Central Tibetan Administration Department of Health (CTA-DOH), the Tibetan Delek Hospital, and three international non-governmental partners, namely the Johns Hopkins University Center for TB Research, Baltimore, MD, USA; the Friends of the Delek Hospital, Dharamsala, India; and the Italian Association for Solidarity among Peoples (AISPO), Milan, Italy. A steering committee of members representing each of the partners oversees the programme. The Tibetan TB Control Programme works in close collaboration with the India’s Revised National TB Control Programme (RNTCP), and all data on TB diagnosis and treatment outcome are currently reported to the RNTCP. In patients with suspected extensively drug-resistant (XDR-) and multidrugresistant TB (MDR-TB), sputum specimens are sent for sputum culture at the Hinduja Microbiology Laboratory in Mumbai, a WHO-approved laboratory facility. All patients who meet the criteria for treatment can receive anti-tuberculosis treatment at Delek Hospital, at CTA-DOH primary health centres and at local Indian government health clinics. Some Tibetan refugees also receive treatment through health facilities run by the RNTCP. First-line anti-tuberculosis drugs are provided free of cost by Delek Hospital, the CTA-DOH and the RNTCP, depending on where a patient seeks care. All Tibetan patients from any CTA-DOH clinic with suspected MDR- or XDR-TB are managed under the supervision of a panel of physicians experienced in the treatment of MDR- and XDRTB. The panel, based at Delek Hospital, regularly reviews all potential cases of MDR- and XDR-TB, provides advice and assistance to doctors in the field and makes recommendations for anti-tuberculosis treatment regimens. Once these recommendations
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have been made, patients can receive treatment at Delek Hospital or another CTA-DOH facility with second-line medications purchased by the programme. A large network of community health providers helps to provide treatment to all the TB patients; every single dose of medication is currently provided under directly observed therapy. Criteria for enrolment of TB cases in the study 1 Any new sputum smear-positive TB case 2 A TB suspect with three sputum smear-negative samples with both clinical and radiological characteristics highly suggestive of TB, defined as: i Cough of .2 weeks plus any of the following: Unexplained weight loss Fever or night sweats Blood in sputum and ii Chest X-ray showing one of the following: Cavity/ies Fibro-nodular consolidation involving apical/ posterior segments of the upper lobes or superior segments of the lower lobes Statistical methods A preliminary analysis was carried out using contingency tables to explore relationships between binary variables. Association between MDR-TB group (Yes/ No) and variables such as sex, age, living settings, country of birth and previous treatment was evaluated using the v2 test at 0.05 level of significance. A binary logistic regression model was adopted to estimate whether and how covariates measured such as age, country of birth, previous history of TB, etc., affect the probability of developing MDR-TB. Odds ratios (ORs) were computed with their 95% confidence intervals (CIs) and v2 test-related P values. Analyses were prepared with R statistical software, version 2.15.2 (R Foundation for Statistical Computing, Vienna, Austria). We also considered several stratifications to avoid confounding issues, such as resistance vs. country of birth separately for female and male patients. Fisher’s exact test was used whenever needed in case of smaller sample size. After an explorative analysis, a multivariate analysis was performed. A multiple logistic regression model enabled us to investigate the joint impact on probability of being in the MDRTB group of a large set of covariates (both quantitative and qualitative) such as sex, age, country of birth (categorised as Tibet vs others [India, Nepal, Bhutan]), immigration to India (1 if immigrant, 0 otherwise), year of immigration, living setting (1 if patients live in a closed community, 0 otherwise) and history of previous treatment (1 old patient, 0 new patient). Variables were selected through stepwise
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The International Journal of Tuberculosis and Lung Disease
regression with backward selection. We also investigated interactions between variables, such as sex and living setting, but none yielded statistically significant results. The final model selected four covariates as significant (at a significance level of 0.05): age, sex, community and history of previous treatment. The model selected to interpret the results is that in which age is treated as a continuous variable (Table). Using the coefficients obtained from the model with age as a continuous variable, we calculated the OR for the different variables and their CIs, and obtained the probability that the Mycobacterium tuberculosis strain is MDR-TB decreases by 1) about half in patients who live in enclosed communities
Table
Model selected to interpret results
Coefficients Community Age Sex New patient
OR 0.49 0.74 0.38 0.28
(enclosed vs open) (every 10 years more) (male vs. female) (new vs. retreatment cases)
95%CI 0.24–0.98 0.72–0.76 0.19–0.77 0.14–0.56
OR ¼ odds ratio; CI ¼ confidence interval.
compared to patients who live in open communities, 2) about three quarters in patients for every 10 years of age, 3) about 20% in male compared to female patients, and 4) about a quarter in patients with history of TB compared to patients with a previous history of TB.
TB DRS among Tibetan refugees
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RESUME
La tuberculose (TB) constitue l’un des principaux probl`emes de sant´e des Tib´etains en exil en Inde. Les cliniciens trouvent fr´equemment des TB pharmaco-r e´ sistantes, mais des donn e´ es pre´ cises manquaient. O B J E C T I F : D´eterminer la proportion de cas r´esistants parmi les patients tib´etains tuberculeux nouveaux et ceux d´eja` trait´es. S C H E M A : Nous avons r´ealis´e une enquˆete de r´esistance aux m´edicaments dans cinq collectivit´es tib´etaines en Inde. Une culture et un test de sensibilit e´ aux m´edicaments (DST) de premi`ere ligne ont e´ t´e r´ealis´es chez tous les patients nouveaux ou d´eja` trait´es entre avril 2010 et septembre 2011. Les DST pour la kanamycine (KM), l’´ethionamide, l’acide para-aminosalicylique et l’ofloxacine (OFX) ont e´ t´e r´ealis´es sur des isolats de TB multir´esistante (TB-MDR). R E S U LT A T S : De 307 patients enrol´ ˆ es, 264 ont eu une culture positive et un DST disponible ; 193 e´ taient des CONTEXTE :
nouveaux cas et 71 avaient d´eja` e´ t´e trait´es. Tous les patients test´es pour le virus de l’immunod´eficience humaine (n ¼ 250) e´ taient n´egatifs. Parmi les nouveaux cas, 14,5% e´ taient TB-MDR et 5,7% e´ taient r´esistants seulement a` l’isoniazide (INH). Parmi les cas d´eja` trait´es, 31,4% e´ taient TB-MDR et 12,7% e´ taient r´esistants a` l’INH seulement. Parmi les isolats TB-MDR, 28,6% des nouveaux cas et 26,1% des cas d´eja` trait´es e´ taient r´esistants a` l’OFX et 7,1% des nouveaux cas et 8,7% des cas d´eja` trait´es e´ taient r´esistants a` la KM. Trois patients avaient une TB ultrar´esistante. C O N C L U S I O N : La TB-MDR est fr´equente chez les nouveaux cas et les cas d´eja` trait´es parmi les Tib´etains en Inde. Les patients tibe´ tains TB-MDR pre´ sentaient d’autres profils de r e´ sistance complexes. Le pourcentage e´ lev´e de souches de TB-MDR r´esistantes a` l’OFX, a` la KM ou aux deux est particuli`erement pr´eoccupant.
RESUMEN M A R C O D E R E F E R E N C I A: La tuberculosis (TB) es uno de los principales problemas de salud en la comunidad tibetana en exilio en la India. Se acepta que la TB farmaco-resistente es frecuente en la pra´ctica cl´ınica, pero se carece de datos precisos. O B J E T I V O: Determinar la proporci on ´ de farmacorresistencia en los casos nuevos y los casos con antecedente de tratamiento en los pacientes tibetanos con diagnostico ´ TB. M E´ T O D O: Se llevo ´ a cabo una encuesta de farmacoresistencia en cinco asentamientos tibetanos en la India, con cultivo y prueba de sensibilidad a los medicamentos antituberculosos (DST) de primera l´ınea en todos los casos consecutivos de TB, nuevos y previamente tratados, que se diagnosticaron entre abril del 2010 y septiembre del 2011, adema´s de DST a kanamicina (KM), etionamida, a´ cido para-aminosalic´ılico y ofloxacino (OFX) a los aislados cl´ınicos TB multidrogorresistentes (TB-MDR). R E S U LT A D O S: Participaron en el estudio 307 pacientes y 264 obtuvieron cultivos positivos y contaban con DST.
De estos, 193 eran casos nuevos y 71 hab´ıan recibido tratamiento previamente. Todos los pacientes en quienes se practico´ la prueba diagnostica ´ del virus de la inmunodeficiencia humana obtuvieron un resultado negativo (n ¼ 250). En los casos nuevos se observo´ un 14,5% de TB-MDR y el 5,7% era monorresistente a isoniazida (INH). En los casos con antecedente de tratamiento se observo´ un 31,4% de casos TB-MDR y un 12,7% de monorresistencia a INH. En los aislados TB-MDR, el 28,6% de los casos nuevos y el 26,1% de los casos previamente tratados eran resistentes a OFX y el 7,1% de los casos nuevos y el 8,7% de los casos con tratamiento previo eran resistentes a KM. Tres pacientes presentaron TB extremadamente drogorresistente. C O N C L U S I O N E S: La TB-MDR es frecuente en los casos nuevos y en los casos con antecedente de tratamiento antituberculoso en la poblacion ´ tibetana de la India. Los pacientes provenientes del T´ıbet que presentan TBMDR exhiben otros tipos complejos de resistencias. Suscita una preocupacion ´ especial el alto porcentaje de cepas TB-MDR con resistencia a OFX, KM o a ambos.
