Asymptomatic peripheral arterial disease is associated with more adverse lower extremity characteristics than intermittent claudication

Abstract

Background: This study assessed functional performance, calf muscle characteristics, peripheral nerve function, and quality of life in asymptomatic persons with peripheral arterial disease (PAD).

Methods and results: PAD participants (n=465) had an ankle brachial index <0.90. Non-PAD participants (n=292) had an ankle brachial index of 0.90 to 1.30. PAD participants were categorized into leg symptom groups including intermittent claudication (n=215) and always asymptomatic (participants who never experienced exertional leg pain, even during the 6-minute walk; n=72). Calf muscle was measured with computed tomography. Analyses were adjusted for age, sex, race, ankle brachial index, comorbidities, and other confounders. Compared with participants with intermittent claudication, always asymptomatic PAD participants had smaller calf muscle area (4935 versus 5592 mm(2); P<0.001), higher calf muscle percent fat (16.10% versus 9.45%; P<0.001), poorer 6-minute walk performance (966 versus 1129 ft; P=0.0002), slower usual-paced walking speed (P=0.0019), slower fast-paced walking speed (P<0.001), and a poorer Short-Form 36 Physical Functioning score (P=0.016). Compared with an age-matched, sedentary, non-PAD cohort, always asymptomatic PAD participants had smaller calf muscle area (5061 versus 5895 mm(2); P=0.009), poorer 6-minute walk performance (1126 versus 1452 ft; P<0.001), and poorer Walking Impairment Questionnaire speed scores (40.87 versus 57.78; P=0.001).

Conclusions: Persons with PAD who never experience exertional leg symptoms have poorer functional performance, poorer quality of life, and more adverse calf muscle characteristics compared with persons with intermittent claudication and a sedentary, asymptomatic, age-matched group of non-PAD persons.

Figure 1

Adjusted associations of leg symptom categories with calf muscle characteristics in persons with PAD. Pairwise P values shown are in reference to participants with IC symptoms. Results are adjusted for age, sex, race, BMI, comorbidities, ABI, smoking, lower extremity revascularization, recruitment cohort, and blocks walked during the past week. Analyses of calf muscle area also are adjusted for tibia length.

Figure 2

Adjusted associations of leg symptom categories with lower extremity performance in persons with PAD. P values represent pairwise relationships relative to IC (reference group). Results are adjusted for age, sex, race, BMI, comorbidities, ABI, smoking, lower extremity revascularization, patient-reported blocks walked during the past week, and recruitment cohort.