Functional Decline in Peripheral Arterial Disease

CONTEXT: Among individuals with lower-extremity peripheral arterial disease (PAD), specific leg symptoms and the ankle brachial index (ABI) are cross-sectionally related to the degree of functional impairment. However, relations between these clinical characteristics and objectively measured functional decline are unknown. OBJECTIVE: To define whether PAD, ABI, and specific leg symptoms predict functional decline at 2-year follow-up. DESIGN, SETTING, AND PARTICIPANTS: Prospective cohort study among 676 consecutively identified individuals (aged > or =55 years) with and without PAD (n = 417 and n = 259, respectively), with baseline functional assessments occurring between October 1, 1998, and January 31, 2000, and follow-up assessments scheduled 1 and 2 years thereafter. PAD was defined as ABI less than 0.90, and participants with PAD were categorized at baseline into 1 of 5 mutually exclusive symptom groups. MAIN OUTCOME MEASURES: Mean annual changes in 6-minute walk performance and in usual-paced and fast-paced 4-m walking velocity, adjusted for age, sex, race, prior-year functioning, comorbid diseases, body mass index, pack-years of cigarette smoking, and patterns of missing data. RESULTS: Lower baseline ABI values were associated with greater mean (95% confidence interval) annual decline in 6-minute walk performance (-73.0 -142 to -4.2 ft for ABI <0.50 vs -58.8 -83.5 to -34.0 ft for ABI 0.50 to <0.90 vs -12.6 -40.3 to 15.1 ft for ABI 0.90-1.50, P =.02). Compared with participants without PAD, PAD participants with leg pain on exertion and rest at baseline had greater mean annual decline in 6-minute walk performance (-111 -173 to -50.0 ft vs -8.67 -36.9 to 19.5 ft, P =.004), usual-pace 4-meter walking velocity (-0.06 -0.09 to -0.02 m/sec vs -0.01 (-0.03 to 0.003] m/sec, P =.02), and fastest-pace 4-meter walking velocity (-0.07 -0.11 to -0.03 m/sec vs -0.02 -0.04 to -0.006 m/sec, P =.046). Compared with participants without PAD, asymptomatic PAD was associated with greater mean annual decline in 6-minute walk performance (-76.8 (-135 to -18.6] ft vs -8.67 (-36.9 to 19.5] ft, P =.04) and an increased odds ratio for becoming unable to walk for 6 minutes continuously (3.63; 95% confidence interval, 1.58-8.36; P =.002). CONCLUSIONS: Baseline ABI and the nature of leg symptoms predict the degree of functional decline at 2-year follow-up. Previously reported lack of worsening in claudication symptoms over time in patients with PAD may be more related to declining functional performance to than lack of disease progression.