High Ankle–Brachial Index in COPD — Marker of Arterial Stiffness or Sampling Artifact? A Clinicoradiological Correlation Study

Abstract

Background: An ankle–brachial index (ABI) > 1.40 denotes non-compressible, calcified arteries and predicts excess cardiovascular mortality, yet its prevalence and determinants in chronic obstructive pulmonary disease (COPD) remain unclear. Objectives: (i) Compare the frequency of high (> 1.40) and low (< 0.90) ABI between stable COPD patients and healthy never-smokers; (ii) identify clinical and radiographic correlates of high ABI within COPD. Methods: Forty-three spirometry-confirmed, exacerbation-free COPD patients and forty-one age-/sex-matched never-smoking volunteers were studied (March 2019 – April 2020). After 10 min supine rest, bilateral ankle and brachial systolic pressures were measured by continuous-wave Doppler; ABI was the higher ankle pressure divided by the higher brachial pressure. Categories: low < 0.90, normal 1.00–1.40, high > 1.40. Chest radiographs were scored for hyperinflation; symptom burden captured with the COPD Assessment Test (CAT). Multivariable logistic regression examined predictors of high ABI. Results: High ABI was more common in COPD (14/43, 32.6 %) than controls (3/41, 7.3 %; p = 0.005). Only one COPD subject exhibited low ABI. COPD patients with high ABI showed more radiographic hyperinflation (71 % vs 23 %, p = 0.01) and higher CAT scores (34 ± 6 vs 28 ± 8, p = 0.03). In adjusted analysis, dyslipidaemia (OR 3.4, 95 % CI 1.2–9.5) and hyperinflation (OR 4.1, 95 % CI 1.3–12.9) independently predicted high ABI, supporting a true arterial-stiffness phenotype rather than cuff artifact. Conclusions: One-third of Himalayan COPD patients harbour abnormally stiff, non-compressible peripheral arteries linked to hyperinflation and metabolic risk. Given its speed, low cost and prognostic power, routine ABI measurement should accompany spirometry for comprehensive cardiovascular stratification in COPD clinics.