Validation of the appropriate use criteria for coronary angiography: a cohort study.

BACKGROUND The use of invasive coronary angiography in stable ischemic heart disease (IHD) varies widely. OBJECTIVE To validate the 2012 appropriate use criteria for diagnostic catheterization by examining the relationship between the appropriateness of cardiac catheterization in patients with suspected stable IHD and the proportion of patients with obstructive coronary artery disease (CAD) and subsequent revascularization. DESIGN Population-based, observational, multicenter cohort study. SETTING The Cardiac Care Network, a registry of all patients having elective angiography at 18 hospitals in Ontario, Canada, between 1 October 2008 and 30 September 2011. PATIENTS Persons without prior coronary revascularization or myocardial infarction who had angiography for suspected stable CAD. MEASUREMENTS Appropriateness scores were ascertained by using data collected at the time of the index angiography and were categorized as appropriate, inappropriate, or uncertain. RESULTS Among the final cohort of 48 336 patients, 58.2% of angiographic studies were classified as appropriate, 10.8% were classified as inappropriate, and 31.0% were classified as uncertain. Overall, 45.5% of patients had obstructive CAD. In patients with appropriate indications for angiography, 52.9% had obstructive CAD, with 40.0% undergoing revascularization. In those with inappropriate indications, 30.9% had obstructive CAD and 18.9% underwent revascularization; in those with uncertain indications, 36.7% had obstructive CAD and 25.9% had revascularization. Although more patients with appropriate indications had obstructive CAD and underwent revascularization (P < 0.001), a substantial proportion of those with inappropriate or uncertain indications had important coronary disease. LIMITATION Data were not available on whether symptoms were atypical. CONCLUSION Despite the association between appropriateness category and obstructive CAD, this study raises concerns about the ability of the appropriate use criteria to guide clinical decision making. PRIMARY FUNDING SOURCE Canadian Institutes of Health Research.