Screening for peripheral artery disease using the ankle-brachial index : an updated systematic review for the U.S. Preventive Services Task Force

Two trials reported conflicting results on total or fatal hemorrhagic CVA risk with wide confidence intervals due to a rare event rate. Two exercise trials (n=932) in populations that were screen-detected or oversampled for no or atypical symptoms reported no differences in quality of life (QOL), th...

Full description

Main Authors: Guirguis-Blake, Janelle, Evans, Corinne V. (Author), Redmond, Nadia (Author), Lin, Jennifer (Author)
Corporate Authors: Oregon Evidence-based Practice Center (Center for Health Research (Kaiser-Permanente Medical Care Program. Northwest Region)), U.S. Preventive Services Task Force, United States Agency for Healthcare Research and Quality
Format: eBook
Language:English
Published: Rockville, MD Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services 2018, July 2018
Series:Evidence synthesis
Subjects:
Online Access:
Collection: National Center for Biotechnology Information - Collection details see MPG.ReNa
Summary:Two trials reported conflicting results on total or fatal hemorrhagic CVA risk with wide confidence intervals due to a rare event rate. Two exercise trials (n=932) in populations that were screen-detected or oversampled for no or atypical symptoms reported no differences in quality of life (QOL), the Walking Impairment Questionnaire (WIQ) walking distance, or symptoms at 12 and 52 weeks. No harms were reported in the exercise trials. LIMITATIONS: Our search was limited to English-language literature. We excluded trials specifically recruiting participants from vascular laboratories for screening accuracy studies and treatment trials of symptomatic populations that would not be generalizable to screen-detected or generally asymptomatic populations.
OBJECTIVE: We conducted this systematic review to support the U.S. Preventive Services Task Force (USPSTF) in updating its recommendation on screening for peripheral artery disease (PAD).
Our review addressed five key questions: 1) Is screening for PAD in generally asymptomatic adults with the ankle-brachial index (ABI) effective in reducing cardiovascular disease (CVD) or PAD morbidity (e.g., impaired ambulation or amputation) or mortality? 2) What is the diagnostic accuracy of the ABI as a screening test for PAD in generally asymptomatic adults? 3) What are the harms of screening for PAD with the ABI? 4) Does treatment of screen-detected or generally asymptomatic adults with PAD or an abnormal ABI lead to improved patient health outcomes? 5) What are the harms of treatment of screen-detected or generally asymptomatic adults with PAD or an abnormal ABI? DATA SOURCES: We searched MEDLINE, PubMed publisher-supplied records, and the Cochrane Central Register of Controlled Trials (CENTRAL) for relevant English-language literature published between January 2012 and May 2, 2017.
Two underpowered exercise trials in screen-detected or atypical and asymptomatic populations show no statistically significant effect on hard health outcomes
Overall, data are limited but suggest that the ABI may not be a sufficiently sensitive screening test to detect PAD in generally asymptomatic adults. Two adequately powered trials (n=4,626) in asymptomatic populations with a low ABI but not meeting typical PAD thresholds (d0.95 or d0.99) with and without diabetes showed no statistically significant effect of aspirin 100 mg daily for composite CVD outcomes (adjusted HR 1.00 [95% CI, 0.81 to 1.23] and HR 0.98 [95% CI, 0.76 to 1.26]); there were no differences seen in individual CVD outcomes or all-cause mortality compared with placebo control after 6 to 8 years of followup. There is no compelling evidence to support a differential treatment effect by age, sex, or diabetes status. Limited evidence from one trial demonstrates a trend toward higher risk for major bleeding events with the use of aspirin; the same trial showed no effect on major GI bleeding.
DATA ANALYSIS: One investigator abstracted data into an evidence table and a second investigator confirmed these data. Two investigators independently assessed study quality using methods developed by the USPSTF. We qualitatively synthesized the data for each key question. RESULTS: No population-based screening trials evaluated the direct benefits or harms of ABI screening alone. We identified a total of five trials (n=5,864 total) examining indirect evidence for the effectiveness and harms of screening and treatment of screen-detected PAD. A single diagnostic accuracy study in a screen-detected older population of adults (n=306) showed that the ABI has low sensitivity (confidence intervals ranging from 7 to 34% in individual limbs) and high specificity (96 to 100%) characteristics compared with MRA gold standard imaging; false negative rates were high (>80%).
Our review protocol prioritized hard health outcomes (PAD and CVD morbidity and mortality; quality of life) and did not include changes in functional testing (e.g., 6-minute walk, lower-extremity strength), changes in the ABI, behavioral changes (e.g., physical activity levels, smoking cessation), or intermediate cardiovascular outcomes (e.g., blood pressure, lipid levels). CONCLUSIONS: The current evidence base for screening for PAD is limited, with no direct evidence examining the effectiveness of ABI screening alone. Indirect evidence is scant and includes a single diagnostic accuracy study of the ABI in an unselected population showing poor sensitivity; two aspirin trials in screen-detected populations (with and without diabetes) with a low ABI defined as d0.95 or d0.99 show no benefit for primary composite cardiovascular outcomes.
One ongoing screening trial was published after the search date and was formally evaluated for inclusion. Additionally, we re-evaluated all studies included in the 2013 review. We supplemented our searches with reference lists from relevant existing systematic reviews, suggestions from experts, and ClinicalTrials.gov to identify ongoing trials. STUDY SELECTION: Two researchers reviewed 4,194 titles and abstracts and 105 full-text articles applying prespecified inclusion criteria. Eligible studies included: randomized controlled or clinically controlled trials and systematic reviews on the effectiveness of PAD screening and early treatment of screen-detected PAD to prevent CVD and PAD morbidity and mortality and quality of life; observational diagnostic accuracy studies and systematic reviews on the accuracy of the ABI to diagnose PAD; and randomized or clinically controlled trials, cohort studies, observational studies, and case-control studies on the harms of screening and treatment.
Physical Description:1 PDF file (vii, 85 pages) illustration