Leg Atherosclerosis in Japanese COPD Patients: Prevalence of Undiagnosed Peripheral Artery Disease and Association between Leg Atherosclerosis and Clinical Indices

Introduction: Several studies have suggested that decreased FEV1 is associated with cardiovascular risk in COPD patients. Objective: To identify the prevalence of undiagnosed peripheral artery disease (PAD) and the relationship between leg atherosclerosis and clinical indices, which predict COPD mortality in Japanese COPD patients. Methods: We performed a cross-sectional study in 51 COPD patients and 51 age-matched, healthy control smokers. We measured ankle-brachial index (ABI) as a marker of atherosclerosis of the legs, pulmonary function, body mass index, modified Medical Research Council (MMRC) dyspnea scale, and smoking pack-years. We also calculated the ADO index (Age, Dyspnea, and Obstruction), an established predictor of mortality in COPD patients. Co-morbidities including diabetes mellitus, hypertension, and hypercholesterolemia were identified from blood laboratory tests and medical records. Results: Five subjects (9.8%) had an ABI < 0.9. ABI was significantly lower in the COPD patients than in the healthy control smokers (p < 0.05). The prevalence of PAD was marginally higher in COPD patients than in control smokers (p = 0.09), with the prevalence of ABI < 1.0 being significantly higher in COPD patients than in control smokers (p = 0.04). In the COPD patients, ABI showed significant correlations with age (p = 0.006), FEV1 (p = 0.004), smoking pack-years (p = 0.047), MMRC dyspnea scale (p = 0.0005), SaO2 (p = 0.001), and ADO index (p < 0.001). Multiple linear regression modeling showed the factors associated independently with ABI were age, FEV1, smoking pack-years, MMRC dyspnea scale, and SaO2. Conclusion: The risk of leg atherosclerosis in Japanese COPD patients is higher than in smokers without COPD. Leg atherosclerosis in COPD patients is associated with clinical indices that predict COPD mortality.