Association between the ankle–brachial index, intermittent claudication, and physical activity level: what is the influence on the functional capacity of patients with or at high risk of cardiovascular disease?

BACKGROUND: Patients with or at high risk of cardiovascular disease have a poor functional capacity; however, the influence of association among intermittent claudication (IC), abnormal ankle–brachial index (ABI), and physical activity level on functional capacity of these patients has not been fully studied. OBJECTIVE: The primary objective of this study was to investigate the association between the ABI, IC, and physical activity level, and the influence of these variables on the functional capacity of patients with or at high risk of cardiovascular disease seen in a reference cardiology outpatient clinic in Southern Brazil. The secondary objective was to assess the prevalence of peripheral arterial disease (PAD) in this sample of patients. PATIENTS AND METHODS: This was a prospective cross-sectional study in which 162 consecutive patients were evaluated and classified into three groups according to their ABI: normal ABI (n=104, values between 1.00 and 1.40); borderline PAD (n=23, values between 0.91 and 1.00); and patients with PAD (n=35, ≤0.90). The presence of IC was assessed using the Edinburgh Claudication Questionnaire. The level of physical activity was assessed by the short version of the International Physical Activity Questionnaire (IPAQ) and functional capacity was assessed by the 6-minute walk distance (6MWD). RESULTS: The prevalence of PAD was 21.6% in the total sample. The 6MWD showed strong correlation with the absence of IC (r=0.785; P<0.001), moderate correlation with age (r=−0.347; P<0.001), and weak correlations with IPAQ scores (r=0.164; P=0.038) and ABI (r=0.216; P=0.006). Age, ABI, and absence of IC were independently associated with the outcome (P=0.001, P=0.001, and P=0.028, respectively). CONCLUSION: The current study demonstrates that 6MWD is associated with IPAQ scores, ABI, and absence of IC. Age, ABI and absence of IC were independently associated with functional capacity in patients with or at high risk of cardiovascular disease.