ORIGINAL PAPER
Relative value of the Ankle-Brachial Index of intermittent claudication F. S. Lozano,1 J. R. March,2 J. R. Gonzalez-Porras,1 E. Carrasco,3 J. M. Lobos,4 E. Ros5
1
Hospital Universitario de Salamanca and IBSAL, Salamanca, Spain 2 Hospital Universitario de Getafe, Madrid, Spain 3 Centro de Salud Jesus H. Gomez Tornero, Abaran, Murcia, Spain 4 Centro de Salud Villablanca, Madrid, Spain 5 Hospital Universitario de Granada, Granada, Spain Correspondence to: Francisco S. Lozano Sanchez, Servicio de Angiologıa y Cirugıa Vascular, Hospital Universitario de Salamanca, Paseo de San Vicente 58 – 182, 37007 Salamanca, Spain Tel.: +34 923 291532 Fax:+34 923 294558 Email: [email protected] Disclosure The authors declare no competing financial interests.
SUMMARY
What’s known
Introduction: The Ankle-Brachial Index (ABI) makes it possible to identify patients with peripheral artery disease (PAD). Intermittent claudication (IC) is the first major symptom of PAD, although many patients with an ABI ≤ 0.9 do not exhibit IC, and the range of ABI among those who do have IC is very variable. This study evaluates the correlation between ABI and the perception (symptomatology) of claudicant patients. Material and methods: An observational, cross-sectional and multicentre, study of 920 patients with IC. Clinical history, ABI, Walking Impairment Questionnaire (WIQ) and European Quality of Life Questionnaire (EQ5D) were recorded. Associations were analysed using Spearman’s correlation coefficient. Results: The mean ABI of the series was 0.63 (SD = 0.19). The mean WIQ-distance was 34.07 (SD = 26.77), values being smaller for lower ABI values (r = 0.343, p < 0.001). The mean EQ-5D score of the series was 0.58 (SD = 0.21), also showing lower values as the ABI decreased (r = 0.278, p < 0.001). The correlations of WIQ and EQ-5D with ABI were statistically significant in both cases, but always less than 0.400 (between 0.278 and 0.343). Conclusions: The correlations of ABI with the questionnaires of walking capacity and quality of life are weak. For this reason, although in clinical practice the ABI of CI patients is commonly measured, decisions should not be taken during the development of IC exclusively on the basis of the ABI.
Introduction Peripheral artery disease (PAD) is a very prevalent condition worldwide and is more serious from a general (cardiovascular mortality) than a local (limb loss) point of view (1–3). It also causes immense social and economic damage. Early diagnosis offers enormous benefit by allowing the course of PAD to be controlled (4). It is usually asymptomatic in its early stages, but intermittent claudication (IC) is subsequently the main symptom leading a patient to seek a medical consultation. Arteriography is currently the gold standard in the diagnosis of PAD but is usually reserved for PAD with surgical indication. The use of the ABI (5) as a simple, accessible, non-invasive, objective and economical test has been implemented in primary healthcare. A recent meta-analysis corroborated that an ABI ≤ 0.90, compared with arteriography, gave a highly sensitive and specific diagnosis of PAD (6). The ABI is also known to be a general marker of arteriosclerosis and a predictor of events and deaths
1478
In clinical practice it is commonplace to measure the Ankle-Brachial Index (ABI) in patients with Intermitent Claudication (IC)
What’s new
• •
As the ABI decreases, patients with IC walk shorter distances free of pain and have a worse quality of life. Decisions concerning IC cannot be made exclusively on the basis of ABI.
of cardiovascular origin (7); it is also useful as a marker of PAD progression, follow-up after revascularisation and other illnesses that are less familiar to vascular surgeons, such as cognitive conditions, dementia and Alzheimer’s disease (8). Nevertheless, the ABI has limitations and imperfections (9). In fact, the ABI is more sensitive for detecting PAD than for identifying claudicants, such that only 10– 30% of patients identified with PAD (ABI < 0.90) exhibit the classic symptoms of IC (10). The objective of this study is to investigate the behaviour of the ABI in a broad group of claudicants and to correlate this with patients’ perceptions of their disease (distance covered and quality of life).
Material and methods Study population We carried out an observational, cross-sectional and multicentre study, covering the whole of Spain. A total of 356 specialists in angiology and vascular surgery were identified to participate in the study. Each
ª 2014 John Wiley & Sons Ltd Int J Clin Pract, December 2014, 68, 12, 1478–1482. doi: 10.1111/ijcp.12499
ABI in claudicants
doctor had to have three to four consecutive patients in their care. Participating patients had to fulfil the inclusion and exclusion criteria set out in Table 1. All of them gave their signed, informed consent. The diagnosis of IC was based on the medical history (including the Edinburgh questionnaire), and physical examination. The study was approved by the Scientific and Ethics Committee of the Clinic Hospital, Barcelona, Spain (Protocol: SEA-NUL-2011-01).
Measurement instruments The clinical history of each patient was taken and further information was obtained from a physical examination, analytical tests (basal blood sugar, total cholesterol and lipidogram), systolic and diastolic blood pressure and the Ankle-Brachial Index (ABI). At the same time, patients self-completed the Walking Impairment Questionnaire (WIQ) and the European Quality of Life questionnaire (EQ-5D). Patient confidentiality (by anonymisation) was observed.
Ankle-Brachial Index A portable Doppler apparatus was used (8 MHz probe). Techniques were applied according to the recommendations of the American Heart Association (11), with the patient supine and at rest. For each patient, systolic blood pressures were measured in the following order: dorsalis pedis and posterior tibial arteries of each leg and both brachials. The ABI of each extremity was calculated by dividing the highest pressure obtained in either of the leg arteries by the maximum brachial value. In the records of
Table 1 Criteria for inclusion and exclusion
Inclusion criteria Intermittent claudication of the limb > l year of history Either male or female Between 45 and 85 years of age Any race Exclusion criteria Patients who did not give informed consent to take part in the study Patients with recent admission or with a terminal illness Systemic diseases that could cause a reduction in overall mobility Recent surgery because of limb peripheral artery disease (with the previous 6 months) Serious psychiatric condition Alcohol or drug addiction Critical arterial ischaemic limb Patient unable to answer the questions in the WIQ or EQ-5D questionnaires WIQ, Walking Impairment Questionnaire; EQ-5D, EuroQol.
ª 2014 John Wiley & Sons Ltd Int J Clin Pract, December 2014, 68, 12, 1478–1482
each patient only the claudicant limb, or the lower ABI in the bilateral cases, was taken into account.
Walking Impairment Questionnaire This is a specific instrument that documents the physical deficit of patients with IC (12). It investigates three domains: (i) distance the patient manages to walk; (ii) speed the patient achieves and (iii) stairclimbing (the number of stairs the patient can climb). The score for each domain ranges between 0% (incapacity) and 100% (full capacity). The version available in Spanish was used (13).
European Quality of Life questionnaire Generic quality of life (QoL) questionnaire (14). We used the first part of the questionnaire, which evaluates the state of health of patients across five dimensions: mobility, self-care, usual activities, pain/ discomfort and anxiety/depression. The scores obtained are summarised in an overall index between 0 (worst possible state of health) and 1 (perfect state of health). The validated Spanish version was used (15).
Statistical analysis The data were collated in a PASW version 18 (IBM, New York, NY) statistics datafile. Continuous variables were summarised as the mean and standard deviation (SD); discrete variables were expressed as percentages. Continuous variables with a Gaussian distribution were compared using unpaired t-tests, while those with a non-Gaussian distribution were compared using the Mann–Whitney test. Discrete variables were compared by the v2 or Fisher’s exact test, the latter being employed when expected percentages were less than 5. We calculated Spearman’s rank correlation coefficient between the different dimensions of the WIQ and the EQ-5D with ABI. Statistical significance was concluded for values of p < 0.05.
Results A total of 920 claudicant patients met the inclusion and exclusion criteria of the study. Their basal characteristics are presented in Table 2. We note a strikingly high level of cardiovascular risk factors (CVRFs) (10.1% had the four risk factors measured, while only 2.6% had none), and the frequent occurrence of cardiovascular comorbidity (30.2% with ischaemic cardiopathy) and osteo-articular comorbidity (45.8% with arthrosis). Of the sample, 94% (865 patients) had an ABI ≤ 0.90, while 6% (55 patients) had an ABI > 0.90. Values of ABI < 0.50 were recorded in 18.5% (170)
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of the patients. The mean ABI of the entire sample was 0.63 (SD = 0.19) (Table 3). Walking capacity (distance and speed) and stairclimbing ability were lower for smaller values of ABI. Likewise, the quality of life was worse for patients with lower ABI values, with a score of 0.46 in the group of patients with an ABI < 0.50 (Table 3). The correlations of WIQ and EQ-5D with ABI were statistically significant in both cases, but always less than 0.400 (between 0.278 and 0.343) (Table 4).
Table 2 Baseline characteristics
Number Age (years) Sex male, n (%) Body mass index (mean SD) Cardiovascular risk factor, n (%) Smoking Current smokers History of smoking Diabetes mellitus Hypertension Dyslipaemia All risk factor (four) Any risk factor Cardiovascular comorbidities*, n (%) Cardiac failure Ischaemic cardiopathy Arrhythmias Valvulopathies Renal failure Stroke Bone – joint disease comorbidities*, n (%) Arthrosis Arthritis Vertebral disc prolapse Lumbar pathologies Trauma Family history of cardiovascular disease, n (%) Foot pulses, n (%) Negative Palpable Blood pressure (mmHg) (mean SD) Systolic Diastolic Analytical findings (mg/dl) (mean SD) Blood glucose Total cholesterol HDL cholesterol LDL cholesterol Triglycerides
920 68.2 9.8 717 (77.9) 27.6 3.6
357 349 477 698 591 93 24
(38.8) (37.9) (51.8) (75.9) (64.2) (10.1) (2.6)
86 278 85 33 77 23
(9.3) (30.2) (9.2) (3.6) (8.4) (2.5)
421 42 81 152 9 541
(45.8) (4.6) (8.8) (16.5) (1.0) (58.8)
553 (60.1) 367 (39.9) 143.4 17.7 81.5 10.6
Discussion We present a series of patients with IC, diagnosed exclusively by vascular surgeons, and with similar levels of CVRFs and comorbidities as other series (16), in which we studied the ABI and demonstrated that patients with lower values generally exhibit greater claudication and have a worse quality of life, although this was not the case for all subgroups, since the correlations of ABI with WIQ and EQ-5D were weak. It is accepted that an ABI ≤ 0.90 is indicative of PAD. Likewise, it is known that claudicant patients have a higher ABI, at rest, than those with critical ischaemia (17,18). We also know that the ABI decreases as the claudication develops (mild-moderate-severe) (18). Most individuals detected in population studies with an ABI ≤ 0.90 are asymptomatic, and in some studies only between 10% and 20% of them exhibited IC (19,20). However, a significant number of people with asymptomatic PAD show progression over one (21). None of this rules out the possibility that in populations exclusively of claudicants, most patients present an ABI of 0.90 to 0.50 (75% of our sample), and that, as in other series, the mean value is 0.60 (22). However, it is important to stress that the range of values of ABI is wide. In particular, two groups differ from the norm (ABI = 0.90 to 0.50). First, there is a small subgroup with an ABI > 0.90, which comprised 3.2% of the patients in the study of McDermott et al. (23) and 6% of those in our series. The second, larger subgroup consists of those with an ABI < 0.50; while Gardner et al. (24) found this to reach 24.6% (18.5% in our series), the figure did not exceed 1% among primary care doctors (25). These differences are important because of their consequences. In the small subgroup of claudicants with supposedly normal ABI values, it is necessary to
Table 3 Walking Impairment Questionnaire (WIQ) and Euro-Qol (EQ-5D) scores by Ankle-brachial Index (ABI)
ABI
130.1 208.4 51.9 128.2 158.9
45.1 47.1 27.8 39.7 77.4
HDL, high-density lipoprotein; LDL, Low-density lipoprotein. Desirable values (mg/dl): Blood glucose: 80–110, Total cholesterol < 200, HDL cholesterol > 45 (men) and > 55 (woman), LDL cholesterol < 130, Triglycerides 40–170. *No disabling.
N (%)
Normal vs. anormal > 0.90 55 ≤ 0.90 865 By category > 0.90 55 0.90 to 0.50 695 < 0.50 170 Total 920
WIQ-distance
(6.0) (94.0) (6.0) (75.5) (18.5)
49.8 (31.62) 31.2 (24.99) 49.82 34.96 15.94 34.07
(31.62) (24.82) (19.26) (26.77)
EQ-5D
0.64 (0.18) 0.58 (0.20) 0.64 0.61 0.46 0.58
(0.18) (0.18) (0.23) (0.21)
Values are expressed in mean (SD).
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Table 4 Correlations of ABI with WIQ and EQ-5D reported in other studies
Author/s, year
No. patients
ABI-WIQ distance
ABI-WIQ speed
ABI-WIQ stairs
ABI-EQ5D
Long et al. (2004) Izquierdo et al. (2005) Myers et al. (2008) Mazari et al. (2010) Jain et al. (2012) Lozano et al. (2013)
108 80 48 178 638 920
0.130 0.290 (p < 0.001) 0.290 (p < 0.05)
0.230 0.160 0.320 – 0.178 0.335
0.260 0.200 0.110 – 0.074 0.298
* * * 0.214 (p < 0.001) None 0.278 (p < 0.001)
†
0.270 (p < 0.001) 0.343 (p < 0.001)
(p > 0.05) (p < 0.05) (p < 0.001) (p < 0.001)
(p > 0.05) (p > 0.05) (p > 0.05) (p < 0.001)
*With SF-36; †With treadmill walking distances.
differentiate between those with borderline (0.90– 0.99) and raised (> 1.3) values, the latter being diabetic patients (26). It is important to note that both are associated with greater cardiovascular mortality and worse QoL (27). In the subgroup with values of ABI < 0.50, which characterises advanced stages of PAD, it is known that for lower ABI values, there is greater cardiovascular mortality. This subgroup comprises patients with more serious claudication and in which a greater reduction in QoL would be expected. Low ABI may be related to a greater presence of CVRFs or comorbidities in IC. A significantly lower ABI has been found in patients with hypertension or angina (28). Conversely, the presence of three, four or five of the components of metabolic syndrome does not influence the ABI of patients with IC if their scores are maintained between 0.65 and 0.70 reduction, irrespective of the number of components (29). As we have found, several other studies have shown that when the ABI decreases, walking capacity (walking distance and speed, above all) is also reduced. However, it should be stressed that these characteristics are only weakly correlated (30–33) (Table 4). Finally, we note the relationship between ABI and QoL; in our study we chose the EQ-5D, which has been tested and validated in IC (18,34). For smaller ABIs the QoL of claudicant patients is lower, above all for values of ABI < 0.50 (35), although the correlation of ABI with the QoL measured with the EQ5D (36) or other QoL questionnaires (30,37) has
References 1 Dormandy JA, Rutherford RB. Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic Inter-Society Consensus (TASC). J Vasc Surg 2000; 31: S1–296. 2 Hirsch AT, Haskal ZJ, Hertzer NR et al. ACC/AHA 2005 guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic). J Am Coll Cardiol 2006; 47: 1239–312.
ª 2014 John Wiley & Sons Ltd Int J Clin Pract, December 2014, 68, 12, 1478–1482
proved to be weak or very weak, leading various authors to conclude that the QoL is independent of the ABI (38,39). In conclusion, as the ABI decreases, patients with IC walk a shorter distance free of pain and have a worse quality of life. However, the correlations of ABI with the questionnaires of walking capacity and quality of life are weak. For this reason, although in clinical practice the ABI of CI patients is commonly measured, decisions should not be made during the development of IC exclusively on the basis of the ABI.
Author contributions FSL, JRM, EC, JML: Conception and design. Grupo Saned: Data collection. Grupo Saned, FSL: Statistical analysis. FSL, JRGP: Analysis and interpretation of results. FSL, JRGP: Writing up article (text, tables and figures). FSL, JRM, JRGP, EC, JML, ER: Final approval of the article.
Funding This study was sponsored by the Spanish Society of Angiology and Vascular Surgery (SEACV), and the project was financed by the Ferrer Group.
Acknowledgements We are grateful to the Saned Group for assistance with technical and statistical aspects of the study.
3 Norgren L, Hiatt WR, Dormandy JA, Nehler MR, Harris KA, Fowkes FG; TASC II Working Group. Inter-society consensus for the management of peripheral arterial disease (TASC II). J Vasc Surg 2007; 45(Suppl. S): S5–67. 4 Hankey GJ, Norman PE, Eikelboom JW. Medical treatment of peripheral arterial disease. JAMA 2006; 295: 547–53. 5 Yao ST, Hobbs JT, Irvine WT. Ankle pressure measurement in arterial disease of the lower extremities. Br J Surg 1968; 55: 859–60.
6 Xu D, Zou L, Xing Y et al. Diagnostic value of ankle-brachial index in peripheral arterial disease: a meta-analysis. Can J Cardiol 2013; 29: 92–8. 7 Criqui MH. Peripheral arterial disease-epidemiological aspects. Vasc Med 2001; 6(3 Suppl.): 3–7. 8 Guerchet M, Aboyans V, Nubukpo P, Lacroix P, Clement JP, Preux PM. Ankle-brachial index as a marker of cognitive impairment and dementia in general population. A systematic review. Atherosclerosis 2011; 216: 251–7.
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9 Manfredini F, Malagoni AM, Manfredini R. Ankle brachial pressure index: faulty or overused? Angiology 2013; 64: 89–92. 10 McDermott MM. The magnitude of the problem of peripheral arterial disease: epidemiology and clinical significance. Cleve Clin J Med 2006; 73(Suppl. 4): S2–7. 11 Aboyans V, Criqui MH, Abraham P et al. American Heart Association Council on Peripheral Vascular Disease; Council on Epidemiology and Prevention; Council on Clinical Cardiology; Council on Cardiovascular Nursing; Council on Cardiovascular Radiology and Intervention, and Council on Cardiovascular Surgery and Anesthesia. Measurement and interpretation of the ankle-brachial index: a scientific statement from the American Heart Association. Circulation 2012; 126: 2890–909. 12 Regensteiner JG, Steiner JF, Panzer RJ, Hiatt WR. Evaluation of walking impairment by questionnaire in patients with peripheral arterial disease. J Vasc Med Biol 1990; 2: 142–52. 13 Lozano FS, March JR, Gonzalez-Porras JR, Carrasco E, Lobos JM, Areitio-Aurtena A; researchers from the VITAL group. Validation of the Walking Impairment Questionnaire for Spanish patients. Vasa 2013; 42: 350–6. 14 Brooks R. EuroQol: the current state of play. Health Policy 1996; 37: 53–72. 15 Badia X, Roset M, Montserrat S, Herdman M, Segura A. The Spanish version of EuroQol: a description and its applications. European Quality of Life scale. Med Clin (Barc) 1999; 112(Suppl. 1): 79–85. 16 Stansby G, Mister R, Fowkes G et al. Prospective registry and evaluation of peripheral arterial risks, events and distribution investigators. High risk of peripheral arterial disease in the United Kingdom: 2-year results of a prospective registry. Angiology 2011; 62: 111–8. 17 de Vries M, Ouwendijk R, Kessels AG et al. Comparison of generic and disease-specific questionnaires for the assessment of quality of life in patients with peripheral arterial disease. J Vasc Surg 2005; 41: 261–8. 18 Chetter IC, Dolan P, Spark JI, Scott DJ, Kester RC. Correlating clinical indicators of lower-limb ischaemia with quality of life. Cardiovasc Surg 1997; 5: 361–6. 19 Hirsch AT, Criqui MH, Treat-Jacobson D et al. Peripheral arterial disease detection, awareness, and
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of life in patients with peripheral vascular disease. J Vasc Surg 2004; 39: 723–7. Izquierdo-Porrera AM, Gardner AW, Bradham DD et al. Relationship between objective measures of peripheral arterial disease severity to self-reported quality of life in older adults with intermittent claudication. J Vasc Surg 2005; 41: 625–30. Myers SA, Johanning JM, Stergiou N, Lynch TG, Longo GM, Pipinos II. Claudication distances and the Walking Impairment Questionnaire best describe the ambulatory limitations in patients with symptomatic peripheral arterial disease. J Vasc Surg 2008; 47: 550–5. Jain A, Liu K, Ferrucci L et al. The Walking Impairment Questionnaire stair-climbing score predicts mortality in men and women with peripheral arterial disease. J Vasc Surg 2012; 55: 1662–73. Bosch JL, Hunik MG. Comparison of the Health Utilities Index Marck 3 (HU13) and EuroQol EQ-5D in patients treated for intermittent claudication. Qual Life Res 2000; 9: 591–601. Aquarius AE, Denollet J, Hamming JF, Van Berge Henegouwen DP, De Vries J. Type-D personality and ankle brachial index as predictors of impaired quality of life and depressive symptoms in peripheral arterial disease. Arch Surg 2007; 142: 662–7. Mazari FA, Carradice D, Rahman MN et al. An analysis of relationship between quality of life indices and clinical improvement following intervention in patients with intermittent claudication due to femoropopliteal disease. J Vasc Surg 2010; 52: 77–84. Mehta T, Venkata Subramaniam A, Chetter I, McCollum P. Assessing the validity and responsiveness of disease-specific quality of life instruments in intermittent claudication. Eur J Vasc Endovasc Surg 2006; 31: 46–52. M€ uller-B€ uhl U, Engeser P, Klimm HD, Wiesemann A. Quality of life and objective disease criteria in patients with intermittent claudication in general practice. Fam Pract 2003; 20: 36–40. Korhonen PE, Sepp€al€a T, Kautiainen H, J€arvenp€a€a S, Aarnio PT, Kivel€a SL. Ankle-brachial index and health-related quality of life. Eur J Cardiovasc Prev Rehabil 2012; 19: 901–7.
Paper received November 2013, accepted June 2014
ª 2014 John Wiley & Sons Ltd Int J Clin Pract, December 2014, 68, 12, 1478–1482
Relative value of the Ankle-Brachial Index of intermittent claudication F. S. Lozano,1 J. R. March,2 J. R. Gonzalez-Porras,1 E. Carrasco,3 J. M. Lobos,4 E. Ros5
1
Hospital Universitario de Salamanca and IBSAL, Salamanca, Spain 2 Hospital Universitario de Getafe, Madrid, Spain 3 Centro de Salud Jesus H. Gomez Tornero, Abaran, Murcia, Spain 4 Centro de Salud Villablanca, Madrid, Spain 5 Hospital Universitario de Granada, Granada, Spain Correspondence to: Francisco S. Lozano Sanchez, Servicio de Angiologıa y Cirugıa Vascular, Hospital Universitario de Salamanca, Paseo de San Vicente 58 – 182, 37007 Salamanca, Spain Tel.: +34 923 291532 Fax:+34 923 294558 Email: [email protected] Disclosure The authors declare no competing financial interests.
SUMMARY
What’s known
Introduction: The Ankle-Brachial Index (ABI) makes it possible to identify patients with peripheral artery disease (PAD). Intermittent claudication (IC) is the first major symptom of PAD, although many patients with an ABI ≤ 0.9 do not exhibit IC, and the range of ABI among those who do have IC is very variable. This study evaluates the correlation between ABI and the perception (symptomatology) of claudicant patients. Material and methods: An observational, cross-sectional and multicentre, study of 920 patients with IC. Clinical history, ABI, Walking Impairment Questionnaire (WIQ) and European Quality of Life Questionnaire (EQ5D) were recorded. Associations were analysed using Spearman’s correlation coefficient. Results: The mean ABI of the series was 0.63 (SD = 0.19). The mean WIQ-distance was 34.07 (SD = 26.77), values being smaller for lower ABI values (r = 0.343, p < 0.001). The mean EQ-5D score of the series was 0.58 (SD = 0.21), also showing lower values as the ABI decreased (r = 0.278, p < 0.001). The correlations of WIQ and EQ-5D with ABI were statistically significant in both cases, but always less than 0.400 (between 0.278 and 0.343). Conclusions: The correlations of ABI with the questionnaires of walking capacity and quality of life are weak. For this reason, although in clinical practice the ABI of CI patients is commonly measured, decisions should not be taken during the development of IC exclusively on the basis of the ABI.
Introduction Peripheral artery disease (PAD) is a very prevalent condition worldwide and is more serious from a general (cardiovascular mortality) than a local (limb loss) point of view (1–3). It also causes immense social and economic damage. Early diagnosis offers enormous benefit by allowing the course of PAD to be controlled (4). It is usually asymptomatic in its early stages, but intermittent claudication (IC) is subsequently the main symptom leading a patient to seek a medical consultation. Arteriography is currently the gold standard in the diagnosis of PAD but is usually reserved for PAD with surgical indication. The use of the ABI (5) as a simple, accessible, non-invasive, objective and economical test has been implemented in primary healthcare. A recent meta-analysis corroborated that an ABI ≤ 0.90, compared with arteriography, gave a highly sensitive and specific diagnosis of PAD (6). The ABI is also known to be a general marker of arteriosclerosis and a predictor of events and deaths
1478
In clinical practice it is commonplace to measure the Ankle-Brachial Index (ABI) in patients with Intermitent Claudication (IC)
What’s new
• •
As the ABI decreases, patients with IC walk shorter distances free of pain and have a worse quality of life. Decisions concerning IC cannot be made exclusively on the basis of ABI.
of cardiovascular origin (7); it is also useful as a marker of PAD progression, follow-up after revascularisation and other illnesses that are less familiar to vascular surgeons, such as cognitive conditions, dementia and Alzheimer’s disease (8). Nevertheless, the ABI has limitations and imperfections (9). In fact, the ABI is more sensitive for detecting PAD than for identifying claudicants, such that only 10– 30% of patients identified with PAD (ABI < 0.90) exhibit the classic symptoms of IC (10). The objective of this study is to investigate the behaviour of the ABI in a broad group of claudicants and to correlate this with patients’ perceptions of their disease (distance covered and quality of life).
Material and methods Study population We carried out an observational, cross-sectional and multicentre study, covering the whole of Spain. A total of 356 specialists in angiology and vascular surgery were identified to participate in the study. Each
ª 2014 John Wiley & Sons Ltd Int J Clin Pract, December 2014, 68, 12, 1478–1482. doi: 10.1111/ijcp.12499
ABI in claudicants
doctor had to have three to four consecutive patients in their care. Participating patients had to fulfil the inclusion and exclusion criteria set out in Table 1. All of them gave their signed, informed consent. The diagnosis of IC was based on the medical history (including the Edinburgh questionnaire), and physical examination. The study was approved by the Scientific and Ethics Committee of the Clinic Hospital, Barcelona, Spain (Protocol: SEA-NUL-2011-01).
Measurement instruments The clinical history of each patient was taken and further information was obtained from a physical examination, analytical tests (basal blood sugar, total cholesterol and lipidogram), systolic and diastolic blood pressure and the Ankle-Brachial Index (ABI). At the same time, patients self-completed the Walking Impairment Questionnaire (WIQ) and the European Quality of Life questionnaire (EQ-5D). Patient confidentiality (by anonymisation) was observed.
Ankle-Brachial Index A portable Doppler apparatus was used (8 MHz probe). Techniques were applied according to the recommendations of the American Heart Association (11), with the patient supine and at rest. For each patient, systolic blood pressures were measured in the following order: dorsalis pedis and posterior tibial arteries of each leg and both brachials. The ABI of each extremity was calculated by dividing the highest pressure obtained in either of the leg arteries by the maximum brachial value. In the records of
Table 1 Criteria for inclusion and exclusion
Inclusion criteria Intermittent claudication of the limb > l year of history Either male or female Between 45 and 85 years of age Any race Exclusion criteria Patients who did not give informed consent to take part in the study Patients with recent admission or with a terminal illness Systemic diseases that could cause a reduction in overall mobility Recent surgery because of limb peripheral artery disease (with the previous 6 months) Serious psychiatric condition Alcohol or drug addiction Critical arterial ischaemic limb Patient unable to answer the questions in the WIQ or EQ-5D questionnaires WIQ, Walking Impairment Questionnaire; EQ-5D, EuroQol.
ª 2014 John Wiley & Sons Ltd Int J Clin Pract, December 2014, 68, 12, 1478–1482
each patient only the claudicant limb, or the lower ABI in the bilateral cases, was taken into account.
Walking Impairment Questionnaire This is a specific instrument that documents the physical deficit of patients with IC (12). It investigates three domains: (i) distance the patient manages to walk; (ii) speed the patient achieves and (iii) stairclimbing (the number of stairs the patient can climb). The score for each domain ranges between 0% (incapacity) and 100% (full capacity). The version available in Spanish was used (13).
European Quality of Life questionnaire Generic quality of life (QoL) questionnaire (14). We used the first part of the questionnaire, which evaluates the state of health of patients across five dimensions: mobility, self-care, usual activities, pain/ discomfort and anxiety/depression. The scores obtained are summarised in an overall index between 0 (worst possible state of health) and 1 (perfect state of health). The validated Spanish version was used (15).
Statistical analysis The data were collated in a PASW version 18 (IBM, New York, NY) statistics datafile. Continuous variables were summarised as the mean and standard deviation (SD); discrete variables were expressed as percentages. Continuous variables with a Gaussian distribution were compared using unpaired t-tests, while those with a non-Gaussian distribution were compared using the Mann–Whitney test. Discrete variables were compared by the v2 or Fisher’s exact test, the latter being employed when expected percentages were less than 5. We calculated Spearman’s rank correlation coefficient between the different dimensions of the WIQ and the EQ-5D with ABI. Statistical significance was concluded for values of p < 0.05.
Results A total of 920 claudicant patients met the inclusion and exclusion criteria of the study. Their basal characteristics are presented in Table 2. We note a strikingly high level of cardiovascular risk factors (CVRFs) (10.1% had the four risk factors measured, while only 2.6% had none), and the frequent occurrence of cardiovascular comorbidity (30.2% with ischaemic cardiopathy) and osteo-articular comorbidity (45.8% with arthrosis). Of the sample, 94% (865 patients) had an ABI ≤ 0.90, while 6% (55 patients) had an ABI > 0.90. Values of ABI < 0.50 were recorded in 18.5% (170)
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of the patients. The mean ABI of the entire sample was 0.63 (SD = 0.19) (Table 3). Walking capacity (distance and speed) and stairclimbing ability were lower for smaller values of ABI. Likewise, the quality of life was worse for patients with lower ABI values, with a score of 0.46 in the group of patients with an ABI < 0.50 (Table 3). The correlations of WIQ and EQ-5D with ABI were statistically significant in both cases, but always less than 0.400 (between 0.278 and 0.343) (Table 4).
Table 2 Baseline characteristics
Number Age (years) Sex male, n (%) Body mass index (mean SD) Cardiovascular risk factor, n (%) Smoking Current smokers History of smoking Diabetes mellitus Hypertension Dyslipaemia All risk factor (four) Any risk factor Cardiovascular comorbidities*, n (%) Cardiac failure Ischaemic cardiopathy Arrhythmias Valvulopathies Renal failure Stroke Bone – joint disease comorbidities*, n (%) Arthrosis Arthritis Vertebral disc prolapse Lumbar pathologies Trauma Family history of cardiovascular disease, n (%) Foot pulses, n (%) Negative Palpable Blood pressure (mmHg) (mean SD) Systolic Diastolic Analytical findings (mg/dl) (mean SD) Blood glucose Total cholesterol HDL cholesterol LDL cholesterol Triglycerides
920 68.2 9.8 717 (77.9) 27.6 3.6
357 349 477 698 591 93 24
(38.8) (37.9) (51.8) (75.9) (64.2) (10.1) (2.6)
86 278 85 33 77 23
(9.3) (30.2) (9.2) (3.6) (8.4) (2.5)
421 42 81 152 9 541
(45.8) (4.6) (8.8) (16.5) (1.0) (58.8)
553 (60.1) 367 (39.9) 143.4 17.7 81.5 10.6
Discussion We present a series of patients with IC, diagnosed exclusively by vascular surgeons, and with similar levels of CVRFs and comorbidities as other series (16), in which we studied the ABI and demonstrated that patients with lower values generally exhibit greater claudication and have a worse quality of life, although this was not the case for all subgroups, since the correlations of ABI with WIQ and EQ-5D were weak. It is accepted that an ABI ≤ 0.90 is indicative of PAD. Likewise, it is known that claudicant patients have a higher ABI, at rest, than those with critical ischaemia (17,18). We also know that the ABI decreases as the claudication develops (mild-moderate-severe) (18). Most individuals detected in population studies with an ABI ≤ 0.90 are asymptomatic, and in some studies only between 10% and 20% of them exhibited IC (19,20). However, a significant number of people with asymptomatic PAD show progression over one (21). None of this rules out the possibility that in populations exclusively of claudicants, most patients present an ABI of 0.90 to 0.50 (75% of our sample), and that, as in other series, the mean value is 0.60 (22). However, it is important to stress that the range of values of ABI is wide. In particular, two groups differ from the norm (ABI = 0.90 to 0.50). First, there is a small subgroup with an ABI > 0.90, which comprised 3.2% of the patients in the study of McDermott et al. (23) and 6% of those in our series. The second, larger subgroup consists of those with an ABI < 0.50; while Gardner et al. (24) found this to reach 24.6% (18.5% in our series), the figure did not exceed 1% among primary care doctors (25). These differences are important because of their consequences. In the small subgroup of claudicants with supposedly normal ABI values, it is necessary to
Table 3 Walking Impairment Questionnaire (WIQ) and Euro-Qol (EQ-5D) scores by Ankle-brachial Index (ABI)
ABI
130.1 208.4 51.9 128.2 158.9
45.1 47.1 27.8 39.7 77.4
HDL, high-density lipoprotein; LDL, Low-density lipoprotein. Desirable values (mg/dl): Blood glucose: 80–110, Total cholesterol < 200, HDL cholesterol > 45 (men) and > 55 (woman), LDL cholesterol < 130, Triglycerides 40–170. *No disabling.
N (%)
Normal vs. anormal > 0.90 55 ≤ 0.90 865 By category > 0.90 55 0.90 to 0.50 695 < 0.50 170 Total 920
WIQ-distance
(6.0) (94.0) (6.0) (75.5) (18.5)
49.8 (31.62) 31.2 (24.99) 49.82 34.96 15.94 34.07
(31.62) (24.82) (19.26) (26.77)
EQ-5D
0.64 (0.18) 0.58 (0.20) 0.64 0.61 0.46 0.58
(0.18) (0.18) (0.23) (0.21)
Values are expressed in mean (SD).
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Table 4 Correlations of ABI with WIQ and EQ-5D reported in other studies
Author/s, year
No. patients
ABI-WIQ distance
ABI-WIQ speed
ABI-WIQ stairs
ABI-EQ5D
Long et al. (2004) Izquierdo et al. (2005) Myers et al. (2008) Mazari et al. (2010) Jain et al. (2012) Lozano et al. (2013)
108 80 48 178 638 920
0.130 0.290 (p < 0.001) 0.290 (p < 0.05)
0.230 0.160 0.320 – 0.178 0.335
0.260 0.200 0.110 – 0.074 0.298
* * * 0.214 (p < 0.001) None 0.278 (p < 0.001)
†
0.270 (p < 0.001) 0.343 (p < 0.001)
(p > 0.05) (p < 0.05) (p < 0.001) (p < 0.001)
(p > 0.05) (p > 0.05) (p > 0.05) (p < 0.001)
*With SF-36; †With treadmill walking distances.
differentiate between those with borderline (0.90– 0.99) and raised (> 1.3) values, the latter being diabetic patients (26). It is important to note that both are associated with greater cardiovascular mortality and worse QoL (27). In the subgroup with values of ABI < 0.50, which characterises advanced stages of PAD, it is known that for lower ABI values, there is greater cardiovascular mortality. This subgroup comprises patients with more serious claudication and in which a greater reduction in QoL would be expected. Low ABI may be related to a greater presence of CVRFs or comorbidities in IC. A significantly lower ABI has been found in patients with hypertension or angina (28). Conversely, the presence of three, four or five of the components of metabolic syndrome does not influence the ABI of patients with IC if their scores are maintained between 0.65 and 0.70 reduction, irrespective of the number of components (29). As we have found, several other studies have shown that when the ABI decreases, walking capacity (walking distance and speed, above all) is also reduced. However, it should be stressed that these characteristics are only weakly correlated (30–33) (Table 4). Finally, we note the relationship between ABI and QoL; in our study we chose the EQ-5D, which has been tested and validated in IC (18,34). For smaller ABIs the QoL of claudicant patients is lower, above all for values of ABI < 0.50 (35), although the correlation of ABI with the QoL measured with the EQ5D (36) or other QoL questionnaires (30,37) has
References 1 Dormandy JA, Rutherford RB. Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic Inter-Society Consensus (TASC). J Vasc Surg 2000; 31: S1–296. 2 Hirsch AT, Haskal ZJ, Hertzer NR et al. ACC/AHA 2005 guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic). J Am Coll Cardiol 2006; 47: 1239–312.
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proved to be weak or very weak, leading various authors to conclude that the QoL is independent of the ABI (38,39). In conclusion, as the ABI decreases, patients with IC walk a shorter distance free of pain and have a worse quality of life. However, the correlations of ABI with the questionnaires of walking capacity and quality of life are weak. For this reason, although in clinical practice the ABI of CI patients is commonly measured, decisions should not be made during the development of IC exclusively on the basis of the ABI.
Author contributions FSL, JRM, EC, JML: Conception and design. Grupo Saned: Data collection. Grupo Saned, FSL: Statistical analysis. FSL, JRGP: Analysis and interpretation of results. FSL, JRGP: Writing up article (text, tables and figures). FSL, JRM, JRGP, EC, JML, ER: Final approval of the article.
Funding This study was sponsored by the Spanish Society of Angiology and Vascular Surgery (SEACV), and the project was financed by the Ferrer Group.
Acknowledgements We are grateful to the Saned Group for assistance with technical and statistical aspects of the study.
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Paper received November 2013, accepted June 2014
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