Oscillometric and Doppler Ankle Brachial Indexes as predictors of all-cause mortality in a Primary Care population.

Abstract

Doppler Ankle Brachial Index (ABI), the non-invasive reference standard for peripheral arterial disease (PAD) in Primary Care, has proved good capacity to predict all-cause mortality. However, the role of oscillometric ABI is uncertain. This study aims to evaluate the ability of oscillometric and Doppler ABI to predict all-cause mortality in a Primary Care population. Oscillometric and Doppler ABI were measured in 203 consecutive subjects with ≥1 cardiovascular risk factors or intermittent claudication. Pathologic ABI was defined when ABI was ≤0.9 or ≥1.4, and when the oscillometer was unable to record a value (oscillometric error). All-cause mortality was ascertained through examination of electronic medical records or telephone contact. After analyzing 602.9 subjects/year, all-cause mortality was recorded in 17 (8.4%) patients. Kaplan-Meier survival curves for oscillometric (Log-Rank test χ2=66.02, P<0.001) and Doppler ABI (Log-Rank test χ2=42.30, P<0.001) showed that a pathologic ABI is associated with all-cause mortality. After adjusting for covariates, the hazard ratio in multivariable Cox regression were 4.52 (95% CI: 1.67-12.18, P=0.003) and 2.08 (95% CI: 0.83-5.18, P=0.117) for oscillometric and Doppler ABI models, respectively. When introducing oscillometric and Doppler ABI simultaneously in the Cox regression model, only oscillometric ABI was an independent predictor with a hazard ratio=7.90 (95% CI: 1.79-34.83, P=0.006). Regarding Doppler ABI, no significant differences were found in all-cause mortality between low ABI (≤0.9) and calcified ABI (≥1.4), (Log-Rank test χ2=0.98, P=0.322). Oscillometric ABI predicted all-cause mortality in a Primary Care population even better than Doppler ABI, irrespective of cardiovascular risk factors. Oscillometric ABI, due to a high feasibility, could routinely identify high-risk patients to implement preventive measures.