Accuracy of in-patients ankle-brachial index measurement by medical students

Ankle brachial index (ABI) is a first line non-invasive screening tool for peripheral arterial disease (PAD) in at risk populations. The need to extend ABI use in large population screening has urged its use by professionals other than vascular physicians. As advocated by the American Heart Association, ABI teaching is part of medical curriculum in several countries. We determine accuracy in ABI measurement by trained medical students compared with an experienced angiologist.

Twelve 6th year medical students underwent 9 days of training at Lausanne University Hospital. Students and an experienced angiologist, blinded to students' results, screened consecutive hospitalised patients aged ≥ 65 or ≥ 50 with at least one cardiovascular risk factor during a 6-week period.

A total of 249 patients were screened of whom 59 (23.7%) met the inclusion criteria. Median age was 80, 45.8% were women, and 6.8% were symptomatic. In total, 116 ABIs were available for analysis. Agreement between students and angiologist was moderate with a k-value of 0.498 (95% confidence interval: 0.389-0.606). Overall accuracy and precision of PAD screening performed by students showed sensitivity of 73.2% and specificity of 88.0%. Positive and negative predictive values were 76.9% and 85.7%, respectively; positive and negative likelihood ratios were 6.3 and 3, respectively.

A nine day training program on ABI measurement is not sufficient for inexperienced medical students to achieve an acceptable diagnostic accuracy in detecting PAD in at risk populations.