Screening for Peripheral Artery Disease Using the Ankle-Brachial Index

Importance: Peripheral artery disease (PAD) is associated with a high risk for cardiovascular events and poor ambulatory function, even in the absence of symptoms. Screening for PAD with the ankle-brachial index (ABI) may identify patients in need of treatment to improve health outcomes. Objective: To systematically review evidence for the US Preventive Services Task Force on PAD screening with the ABI, the diagnostic accuracy of the test, and the benefits and harms of treatment of screen-detected PAD. Data Sources: MEDLINE, PubMed, and the Cochrane Central Register of Controlled Trials for relevant English-language studies published between January 2012 and May 2, 2017. Surveillance continued through February 7, 2018. Study Selection: Studies of unselected or generally asymptomatic adults with no known cardiovascular disease. Data Extraction and Synthesis: Independent critical appraisal and data abstraction by 2 reviewers. Main Outcomes and Measures: Cardiovascular morbidity; PAD morbidity; mortality; health-related quality of life; diagnostic accuracy; and serious adverse events. Results: Five studies (N = 5864 participants) were included that examined the indirect evidence for the benefits and harms of screening and treatment of screen-detected PAD. No population-based screening trials evaluated the direct benefits or harms of PAD screening with the ABI alone. A single diagnostic accuracy study of the ABI compared with magnetic resonance angiography gold-standard imaging (n = 306) found low sensitivity (7%-34%) and high specificity (96%-100%) in a screening population. Two adequately powered trials (n = 4626) in asymptomatic populations with and without diabetes with a variably defined low ABI (≤0.95 or ≤0.99) showed no statistically significant effect of aspirin (100 mg daily) for composite CVD outcomes (adjusted hazard ratio HR, 1.00 95% CI, 0.81-1.23 and HR, 0.98 95% CI, 0.76-1.26). One trial (n = 3350) demonstrated no statistically significant increase in major bleeding events with the use of aspirin (adjusted HR, 1.71 95% CI, 0.99- 2.97) and no statistically significant increase in major gastrointestinal bleeding (relative risk, 1.13 95% CI, 0.44-2.91). Two exercise trials (n = 932) in screen-relevant populations reported no differences in quality of life, Walking Impairment Questionnaire walking distance, or symptoms at 12 and 52 weeks; no harms were reported. Conclusions and Relevance: There was no direct evidence and limited indirect evidence on the benefits of PAD screening with the ABI in unselected or asymptomatic populations. Available studies suggest low sensitivity and lack of beneficial effect on health outcomes, but these studies have important limitations.