Validation of the auscultatory method for diagnosing peripheral arterial disease

Background. The Ankle brachial index (ABI) has been shown to be useful in diagnosing peripheral arterial disease (PAD). Ankle systolic blood pressures are measured by a Doppler device; however, general physicians cannot always use it in daily practice. The ausculutatory method (AUS) is an alternative method and quite easy to perform, but has not yet been validated in diagnosing PAD. Objective. To validate AUS for diagnosing PAD based on ABI, compared with Doppler method as gold standard. Methods. Cross-sectional study. Study subjects were 119 patients aged 50 years and older, who were consecutively admitted to the division of general internal medicine in two community hospitals in Japan. We measured the systolic blood pressures of the brachial and the posterior tibial arteries by two methods. We calculated the ABI from the systolic blood pressure obtained by these two methods. PAD was considered to be present when ABI ≤0.90 by the Doppler method. Results. PAD was diagnosed in 22 (18.5%) of 119 patients. Korotkoff sounds of legs were inaudible by AUS in 47 (39.5%) patients. The likelihood ratios for diagnosing PAD patients by AUS were 2.7 (95% CI 1.9 to 3.9) in cases with inaudible Korotkoff sounds, 0.7 (95% CI 0.2 to 1.9) when ABI ≤0.9 and 0.09 (95% CI 0.02 to 0.4) when ABI >0.9. Conclusions. While AUS is not efficient enough to confirm the presence of PAD based on ABI, it could be clinically useful in excluding PAD when ABI >0.90. When measuring ankle blood pressure by AUS in the daily practice, it is important to realise its strengths and weaknesses.