INT J TUBERC LUNG DIS 18(2):141–146 © 2014 The Union http://dx.doi.org/10.5588/ijtld.13.0357
Surveillance of tuberculosis treatment outcomes of Singapore citizens and permanent residents, 2002–2011 C. B. E. Chee,* L. K. Y. Lim,* K. W. KhinMar,* K. Y. Han,* S. H. Gan,* J. Cutter,† P. L. Ooi,† Y. T. Wang* * Singapore Tuberculosis Control Unit, † Communicable Diseases Division, Ministry of Health, Singapore SUMMARY SETTING:
Singapore, which had a tuberculosis (TB) incidence rate of 41 per 100 000 resident population in 2011. O B J E C T I V E : To report the outcomes of Singapore citizens and permanent residents treated for TB from 2002 to 2011. M E T H O D S : A computerised treatment surveillance module (TSM) was launched in 2001 to track the progress and outcome of TB patients nationally. Physicians were required to submit an electronic or paper return for every patient at each clinic visit. Treatment adherence, drugs prescribed, treatment delivery mode and final outcome, specified as ‘completed treatment’, ‘lost to followup’, ‘death’, ‘transferred out’, ‘permanent cessation of treatment’ and ‘still on treatment/no final outcome’, were captured. Quarterly cohort outcomes at 12–15 months
after starting treatment were combined to generate annual treatment outcomes. R E S U LT S : Treatment completion rates increased from 73.4% to 82.8%. The proportion of patients lost to follow-up decreased from 3.4% to 1.7%, while that of patients still on treatment or with no final outcome decreased from 10.5% to 4.4%. The death rate ranged between 10.2% and 11.7%; the majority were not attributed to TB. C O N C L U S I O N : TB treatment completion among Singapore citizens and permanent residents has improved since 2002 as the likely result of the TSM and other initiatives introduced over the past decade. K E Y W O R D S : death; default; treatment completion; DOT
SINGAPORE is an island city-state of 714 km2 with a population of 5.31 million in 2012, comprising 3.82 million citizens and permanent residents, and 1.49 million long-term pass holders.1 Among citizens and permanent residents, the demographic is that of a rapidly aging population: the median age is 38.4 years, and 9% are aged ⩾65 years.1 In Singapore, the tuberculosis (TB) incidence rate among citizens and permanent residents declined markedly from ~300 new cases/100 000 population in the early 1960s to 50–55/100 000 between the years 1987 and 1997.2 This decade-long stagnation in the TB incidence rate prompted a review of the National TB Programme (NTP) and the tightening of control measures from 1997 under the Singapore Tuberculosis Elimination Programme (STEP).3,4 Key STEP interventions were directly observed treatment (DOT), enhanced surveillance of TB cases using a computerised treatment surveillance module (TSM), and a national policy of contact screening for active TB and latent tuberculous infection. Following the launch of the STEP, Singapore’s TB incidence rate among citizens and permanent residents declined from 57/100 000 in 1998 to
35/100 000 in 2007. This trend reversed, however, from 2008, with incidence rising to 41/100 000 in 2011.5 In 1958, Singapore created a National TB Notification Registry, which was computerised from 1986. The system was capable of tracking TB notifications and culture results, but did not monitor treatment outcomes.6 The new TSM, launched in 2000, provides real-time surveillance of treatment progress and outcome of TB cases. We have reported our first year’s experience with TSM and treatment outcomes for pulmonary TB patients treated in 2001.7 The present report analyses the trend in treatment outcomes of notified TB cases among Singapore citizens and permanent residents from 2002 to 2011.
METHODS By law, notification of TB cases within 72 hours of diagnosis is compulsory in Singapore. In addition to receiving notifications from physicians, the national TB registry also captures the results of all mycobacterial cultures and drug susceptibility tests performed in Singapore via electronic linkage to the two laboratories
Correspondence to: Cynthia Chee, Department of Respiratory Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore City, Singapore 308433. Tel: (+65) 256 6011. Fax: (+65) 357 7871. e-mail: [email protected] Article submitted 21 May 2013. Final version accepted 24 September 2013.
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in the country that perform mycobacterial culture. This enables the registry to identify non-notified, culture-positive patients so that a reminder is sent to the physician to notify the cases and manage them accordingly. The computerised TSM covers all notified TB cases in Singapore, of which the majority are treated at the TB Control Unit (i.e., under the NTP), approximately one third by six government restructured hospitals, and a small minority in the private sector. The TSM requires every treating physician to provide reports (via faxed hard-copy forms or electronically) at each clinic visit of the patient’s adherence to treatment, medications prescribed, treatment delivery mode and time to the next review. These reports are submitted until a final outcome is reached. Reminder letters are sent if reports are not submitted within 2 weeks of the date of the scheduled review. Compliance of treatment centres with the TSM, as indicated by the number of reminders sent, is fed back to each centre on a 6-monthly basis. The main aims of the TSM are to monitor national treatment outcomes, a key indicator of programme performance, and to track the treatment progress of patients so that timely action may be taken by their physicians should patients default from clinic appointments. Ethics approval was not sought for this study, as the analysis was performed for the evaluation of NTP performance. Treatment outcomes were determined on a quarterly cohort basis at the end of each corresponding quarter of the following year; therefore, members of the cohort would have had at least 12 months, and at most 15 months, to achieve a treatment outcome. The outcomes of the four quarters of each year were then combined to generate treatment outcomes for that year. Treatment outcomes were categorised by the treating physician into the following: ‘completed treatment’ (with or without ‘cure’), ‘lost to follow-up’, ‘death’ (cause of death has been required to be specified since 2005), ‘transferred out’ and ‘permanent cessation of treatment’. ‘Completed treatment’ was used for patients considered by the physician to have been compliant with at least 80% of medications during the length of treatment. ‘Cure’ in the case of a bacteriologically sputum-positive patient was defined as treatment completion and demonstration of at least two negative sputum smears and/or cultures during the continuation phase, one of which was at the end of treatment. This outcome was retrospectively ascertained by the Registry, as the sputum culture results at or near the end of treatment would not have been available at the point of submission of final outcome by the treating physician. Patients who had not completed treatment at the end of the corresponding quarter 12–15 months after starting treatment were categorised as ‘still on treatment’. Before 2004, these patients were labelled as having ‘no final outcome’. ‘Lost to follow-up’ was used for treatment defaulters
who could not be located at the end of the corresponding quarter at 12–15 months from the start of treatment.
RESULTS Of the 15 213 TB cases notified among Singapore citizens and permanent residents from 2002 to 2011, 687 (4.5%) did not enter the TSM: 601 (3.9%) cases died before treatment could be started and 86 were not started on treatment for various reasons. The proportion of cases who did not enter the TSM decreased from 4.2–6.9% in 2002–2005 to 3.2–4.2% in 2006–2011. These cases were excluded from the present analysis. Of the 14 526 TB cases included in the TSM during the study period, 12 948 were new cases, 1380 were relapses, 125 were reinstated (defined as cases who were re-started on treatment after having interrupted treatment for >1 year) and 73
Figure 1 A. Proportion treated under the NTP and the national DOT rate for the treatment cohorts of Singapore citizens and permanent residents for the period 2002–2011. Over this period, the proportion of patients treated under the NTP increased from 55.1% to 73.9% and the national DOT rate increased from 48.6% to 62.8%. B. Statistically significant correlation coefficient between the national DOT rate and proportion of patients treated under the NTP for the years 2002– 2011. NTP = National Tuberculosis Programme; DOT = directly observed treatment.
TB treatment outcomes in Singapore
were of uncertain status. There were 11374 (78.3%) purely pulmonary cases, 1207 (8.3%) cases with pulmonary and extra-pulmonary TB, and 1945 (13.4%) with purely extra-pulmonary sites of disease. Of the 12 581 pulmonary cases, 75.7% were sputum culturepositive and 48.1% were sputum acid-fast bacilli smear-positive. The proportion of citizens and permanent residents with TB treated under the NTP increased from 55.1% to 73.9% from 2002 to 2011 (Figure 1A). DOT was used for the majority of ambulatory patients treated at the TB Control Unit, and was administered at the public health polyclinic nearest to the patient’s home. As the proportion of cases treated under the NTP increased, the national DOT rate increased correspondingly, from 48.6% to 62.8% (Figure 1, A and B). Figure 2 shows the adherence of the treating physicians to the TSM, as indicated by the number of reminders sent for the yearly cohorts. These decreased from 1469 in 2002 to 501 in 2011. The number of patients for whom reminders were sent similarly decreased, from 785 in 2002 to 256 in 2011. Over the study period, the treatment completion rate improved from 73.4% to 82.8% (Figure 3). The proportion of bacteriologically sputum-positive patients who fulfilled the definition of ‘cure’ increased from 62% to 69% from 2006 to 2011. Non-fulfilment of ‘cure’ was universally due to failure to perform sputum mycobacterial cultures in the continuation phase or at the end of treatment. The proportion of patients
143
Figure 2 Number of patients in each yearly cohort, number of reminders sent and number of patients for whom reminders were sent, 2002–2011. The number of reminders decreased from 1469 and 1590 in 2002 and 2003, respectively, to 501 in 2011. The number of patients for whom reminders were sent decreased from 785 and 804 in 2002 and 2003, respectively, to 256 in 2011.
lost to follow-up and that of patients still on treatment or with no final outcome fell from 3.4% to 1.7% and from 10.5% to 4.4%, respectively (Figure 3). The outcomes ‘transferred out’ (i.e., the patient left the country), and ‘permanent cessation of treatment’ (due mainly to drug reactions) each accounted for
Surveillance of tuberculosis treatment outcomes of Singapore citizens and permanent residents, 2002–2011 C. B. E. Chee,* L. K. Y. Lim,* K. W. KhinMar,* K. Y. Han,* S. H. Gan,* J. Cutter,† P. L. Ooi,† Y. T. Wang* * Singapore Tuberculosis Control Unit, † Communicable Diseases Division, Ministry of Health, Singapore SUMMARY SETTING:
Singapore, which had a tuberculosis (TB) incidence rate of 41 per 100 000 resident population in 2011. O B J E C T I V E : To report the outcomes of Singapore citizens and permanent residents treated for TB from 2002 to 2011. M E T H O D S : A computerised treatment surveillance module (TSM) was launched in 2001 to track the progress and outcome of TB patients nationally. Physicians were required to submit an electronic or paper return for every patient at each clinic visit. Treatment adherence, drugs prescribed, treatment delivery mode and final outcome, specified as ‘completed treatment’, ‘lost to followup’, ‘death’, ‘transferred out’, ‘permanent cessation of treatment’ and ‘still on treatment/no final outcome’, were captured. Quarterly cohort outcomes at 12–15 months
after starting treatment were combined to generate annual treatment outcomes. R E S U LT S : Treatment completion rates increased from 73.4% to 82.8%. The proportion of patients lost to follow-up decreased from 3.4% to 1.7%, while that of patients still on treatment or with no final outcome decreased from 10.5% to 4.4%. The death rate ranged between 10.2% and 11.7%; the majority were not attributed to TB. C O N C L U S I O N : TB treatment completion among Singapore citizens and permanent residents has improved since 2002 as the likely result of the TSM and other initiatives introduced over the past decade. K E Y W O R D S : death; default; treatment completion; DOT
SINGAPORE is an island city-state of 714 km2 with a population of 5.31 million in 2012, comprising 3.82 million citizens and permanent residents, and 1.49 million long-term pass holders.1 Among citizens and permanent residents, the demographic is that of a rapidly aging population: the median age is 38.4 years, and 9% are aged ⩾65 years.1 In Singapore, the tuberculosis (TB) incidence rate among citizens and permanent residents declined markedly from ~300 new cases/100 000 population in the early 1960s to 50–55/100 000 between the years 1987 and 1997.2 This decade-long stagnation in the TB incidence rate prompted a review of the National TB Programme (NTP) and the tightening of control measures from 1997 under the Singapore Tuberculosis Elimination Programme (STEP).3,4 Key STEP interventions were directly observed treatment (DOT), enhanced surveillance of TB cases using a computerised treatment surveillance module (TSM), and a national policy of contact screening for active TB and latent tuberculous infection. Following the launch of the STEP, Singapore’s TB incidence rate among citizens and permanent residents declined from 57/100 000 in 1998 to
35/100 000 in 2007. This trend reversed, however, from 2008, with incidence rising to 41/100 000 in 2011.5 In 1958, Singapore created a National TB Notification Registry, which was computerised from 1986. The system was capable of tracking TB notifications and culture results, but did not monitor treatment outcomes.6 The new TSM, launched in 2000, provides real-time surveillance of treatment progress and outcome of TB cases. We have reported our first year’s experience with TSM and treatment outcomes for pulmonary TB patients treated in 2001.7 The present report analyses the trend in treatment outcomes of notified TB cases among Singapore citizens and permanent residents from 2002 to 2011.
METHODS By law, notification of TB cases within 72 hours of diagnosis is compulsory in Singapore. In addition to receiving notifications from physicians, the national TB registry also captures the results of all mycobacterial cultures and drug susceptibility tests performed in Singapore via electronic linkage to the two laboratories
Correspondence to: Cynthia Chee, Department of Respiratory Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore City, Singapore 308433. Tel: (+65) 256 6011. Fax: (+65) 357 7871. e-mail: [email protected] Article submitted 21 May 2013. Final version accepted 24 September 2013.
142
The International Journal of Tuberculosis and Lung Disease
in the country that perform mycobacterial culture. This enables the registry to identify non-notified, culture-positive patients so that a reminder is sent to the physician to notify the cases and manage them accordingly. The computerised TSM covers all notified TB cases in Singapore, of which the majority are treated at the TB Control Unit (i.e., under the NTP), approximately one third by six government restructured hospitals, and a small minority in the private sector. The TSM requires every treating physician to provide reports (via faxed hard-copy forms or electronically) at each clinic visit of the patient’s adherence to treatment, medications prescribed, treatment delivery mode and time to the next review. These reports are submitted until a final outcome is reached. Reminder letters are sent if reports are not submitted within 2 weeks of the date of the scheduled review. Compliance of treatment centres with the TSM, as indicated by the number of reminders sent, is fed back to each centre on a 6-monthly basis. The main aims of the TSM are to monitor national treatment outcomes, a key indicator of programme performance, and to track the treatment progress of patients so that timely action may be taken by their physicians should patients default from clinic appointments. Ethics approval was not sought for this study, as the analysis was performed for the evaluation of NTP performance. Treatment outcomes were determined on a quarterly cohort basis at the end of each corresponding quarter of the following year; therefore, members of the cohort would have had at least 12 months, and at most 15 months, to achieve a treatment outcome. The outcomes of the four quarters of each year were then combined to generate treatment outcomes for that year. Treatment outcomes were categorised by the treating physician into the following: ‘completed treatment’ (with or without ‘cure’), ‘lost to follow-up’, ‘death’ (cause of death has been required to be specified since 2005), ‘transferred out’ and ‘permanent cessation of treatment’. ‘Completed treatment’ was used for patients considered by the physician to have been compliant with at least 80% of medications during the length of treatment. ‘Cure’ in the case of a bacteriologically sputum-positive patient was defined as treatment completion and demonstration of at least two negative sputum smears and/or cultures during the continuation phase, one of which was at the end of treatment. This outcome was retrospectively ascertained by the Registry, as the sputum culture results at or near the end of treatment would not have been available at the point of submission of final outcome by the treating physician. Patients who had not completed treatment at the end of the corresponding quarter 12–15 months after starting treatment were categorised as ‘still on treatment’. Before 2004, these patients were labelled as having ‘no final outcome’. ‘Lost to follow-up’ was used for treatment defaulters
who could not be located at the end of the corresponding quarter at 12–15 months from the start of treatment.
RESULTS Of the 15 213 TB cases notified among Singapore citizens and permanent residents from 2002 to 2011, 687 (4.5%) did not enter the TSM: 601 (3.9%) cases died before treatment could be started and 86 were not started on treatment for various reasons. The proportion of cases who did not enter the TSM decreased from 4.2–6.9% in 2002–2005 to 3.2–4.2% in 2006–2011. These cases were excluded from the present analysis. Of the 14 526 TB cases included in the TSM during the study period, 12 948 were new cases, 1380 were relapses, 125 were reinstated (defined as cases who were re-started on treatment after having interrupted treatment for >1 year) and 73
Figure 1 A. Proportion treated under the NTP and the national DOT rate for the treatment cohorts of Singapore citizens and permanent residents for the period 2002–2011. Over this period, the proportion of patients treated under the NTP increased from 55.1% to 73.9% and the national DOT rate increased from 48.6% to 62.8%. B. Statistically significant correlation coefficient between the national DOT rate and proportion of patients treated under the NTP for the years 2002– 2011. NTP = National Tuberculosis Programme; DOT = directly observed treatment.
TB treatment outcomes in Singapore
were of uncertain status. There were 11374 (78.3%) purely pulmonary cases, 1207 (8.3%) cases with pulmonary and extra-pulmonary TB, and 1945 (13.4%) with purely extra-pulmonary sites of disease. Of the 12 581 pulmonary cases, 75.7% were sputum culturepositive and 48.1% were sputum acid-fast bacilli smear-positive. The proportion of citizens and permanent residents with TB treated under the NTP increased from 55.1% to 73.9% from 2002 to 2011 (Figure 1A). DOT was used for the majority of ambulatory patients treated at the TB Control Unit, and was administered at the public health polyclinic nearest to the patient’s home. As the proportion of cases treated under the NTP increased, the national DOT rate increased correspondingly, from 48.6% to 62.8% (Figure 1, A and B). Figure 2 shows the adherence of the treating physicians to the TSM, as indicated by the number of reminders sent for the yearly cohorts. These decreased from 1469 in 2002 to 501 in 2011. The number of patients for whom reminders were sent similarly decreased, from 785 in 2002 to 256 in 2011. Over the study period, the treatment completion rate improved from 73.4% to 82.8% (Figure 3). The proportion of bacteriologically sputum-positive patients who fulfilled the definition of ‘cure’ increased from 62% to 69% from 2006 to 2011. Non-fulfilment of ‘cure’ was universally due to failure to perform sputum mycobacterial cultures in the continuation phase or at the end of treatment. The proportion of patients
143
Figure 2 Number of patients in each yearly cohort, number of reminders sent and number of patients for whom reminders were sent, 2002–2011. The number of reminders decreased from 1469 and 1590 in 2002 and 2003, respectively, to 501 in 2011. The number of patients for whom reminders were sent decreased from 785 and 804 in 2002 and 2003, respectively, to 256 in 2011.
lost to follow-up and that of patients still on treatment or with no final outcome fell from 3.4% to 1.7% and from 10.5% to 4.4%, respectively (Figure 3). The outcomes ‘transferred out’ (i.e., the patient left the country), and ‘permanent cessation of treatment’ (due mainly to drug reactions) each accounted for
