Reliability of the Edinburgh Claudication Questionnaire for Identifying Symptomatic PAD in General Practice.

The Edinburgh Claudication Questionnaire (ECQ) was developed to help identify peripheral arterial disease (PAD) in the general population but has not been validated against diagnostic arterial imaging methods such as Duplex Vascular Ultrasound Scanning (DUS). In the present study, we assessed the accuracy of the ECQ for diagnosis using DUS. As part of a National Institute of Health Research funded project looking at novel diagnostic methods, 250 patients were studied from 15 general practices across North East England from May 2015 and November 2016. Practices identified those with a PAD diagnosis from their registers as well as age- and sex-matched controls. All the ECQs were recorded by a vascular specialist nurse. Duplex vascular ultrasound scanning was used as a reference standard for the diagnosis of occlusive PAD. The ECQ had a sensitivity of 52.5% (95% CI: 42.3%-62.5%), specificity of 87.1% (95% CI: 80.6%-92.0%), positive likelihood ratio of 4.06 (95% CI: 2.57-6.42), and negative likelihood ratio of 0.55 (95% CI: 0.44-0.68) compared with reference standard DUS. The ECQ has relatively poor overall diagnostic test accuracy in isolation. It may be helpful in ruling out PAD or as a supplementary test to improve diagnosis of symptomatic disease in General Practice.