The Ankle-Brachial Index for Peripheral Artery Disease Screening and Cardiovascular Disease Prediction Among Asymptomatic Adults: A Systematic Evidence Review for the US Preventive Services Task Force

Background: Screening for peripheral artery disease (PAD) may reduce morbidity and mortality. Purpose: To review the evidence on the ability of the ankle-brachial index (ABI) to predict cardiovascular disease (CVD) morbidity and mortality independent of Framingham Risk Score (FRS) factors in asymptomatic adults and on the benefits and harms of treating screen-detected adults with PAD. Data Sources: MEDLINE and the Cochrane Central Register of Controlled Trials (1996 to September 2012), clinical trial registries, reference lists, and experts. Study Selection: English-language, population-based prognostic studies evaluating the ABI in addition to the FRS and treatment trials or studies of treatment harms in screen-detected adults with PAD. Data Extraction: Dual quality assessment and abstraction of relevant study details. Data Synthesis: One large meta-analysis (n = 43 919) showed that the ABI could reclassify 10-year risk for coronary artery disease (CAD), but it did not report measures of appropriate reclassification (the net reclassification improvement [NRI]). Four heterogeneous risk prediction studies showed that the magnitude of the NRI was probably small when the ABI was added to the FRS to predict CAD or CVD events. Of 2 treatment trials meeting inclusion criteria, 1 large trial (n = 3350) showed that low-dose aspirin did not prevent CVD events in persons with a screen-detected low ABI but may have increased the risk for major bleeding events. Limitations: Most prognostic studies did not allow for calculation of a bias-corrected NRI. Evidence on treatment benefits and harms was limited to aspirin and was scant. Conclusion: Adding the ABI to the FRS probably has limited value for predicting CAD or CVD. Treatment benefits for asymptomatic individuals with screen-detected PAD are not established.