Accuracy of Peripheral Arterial Disease Registers in UK General Practice: Case-Control Study

Abstract

Background: Approximately 20% of the UK population aged 55 to 75 years have evidence of peripheral arterial disease (PAD). PAD affects quality of life and life expectancy if not appropriately diagnosed and managed. At risk patients require accurate diagnosis to ensure optimal treatment to slow disease progression and minimize adverse outcomes. Aim: To assess the accuracy of general practice (GP) registration of the diagnosis of peripheral arterial disease (PAD). Design and Setting: An observational analytic case-control study. As part of a National Institute for Health Research–funded (ISRCTN13301188) project assessing novel diagnostic methods set in GP practice. Methods: A total of 125 patients registered as having PAD and 125 age- and sex-matched controls were recruited from 15 general practices across North East England. The register was then assessed for accuracy of diagnosis. Duplex vascular ultrasound scanning (DUS) undertaken by vascular scientists was used as the gold standard reference for PAD. Results: The PAD register had a sensitivity of 86% (95% CI 77%-92%) and specificity of 74% (95% CI 67%-81%) when compared with DUS. The positive predictive value, however, was 69.6% (95% CI 63%-75%) and negative predictive value 88.8% (95% CI 82%-92%). The overall diagnostic effectiveness of the PAD register was 79.2% (95% CI 73%-84%). Conclusion: This analysis indicates that while PAD is detected with reasonable sensitivity in primary care, many patients registered with a diagnosis of PAD lacked DUS-proven disease. Improved approaches to the objective diagnosis of PAD may improve diagnosis and management of PAD in primary care.