Variations in Use of Optimal Medical Therapy in Patients With Nonobstructive Coronary Artery Disease: A Population‐Based Study

BACKGROUND: There is a paucity of data on the need for optimal medical therapy (OMT) in nonobstructive coronary artery disease . We sought to understand if there was variation in the use of OMT between hospitals for patients with nonobstructive coronary artery disease, the factors associated with such variation, and its clinical consequences. METHODS AND RESULTS: Using a population‐level clinical registry in Ontario, Canada, we identified all patients >66 years undergoing coronary angiography for the indication of stable angina, who had nonobstructive coronary artery disease between November 1, 2010, and October 31, 2013. Hierarchical multivariable logistic models were developed to identify the factors associated with OMT use, with median odds ratio used to quantify the degree of variation between hospitals not explained by the modeled risk factors. Clinical outcomes of interest were all‐cause mortality and rehospitalization, with follow‐up until March 31, 2015. Our cohort consisted of 5413 patients, of whom 2554 (47.2%) were receiving OMT within 1 year. There was a 2‐fold variation in OMT across hospitals (30.4%–61.8%). The variation between hospitals was fully explained by preangiography medication use (median odds ratio of 1.21 in the null model and 1.03 in the full model). There was no difference in risk‐adjusted mortality (hazard ratio, 0.94; 95% confidence interval, 0.76–1.16); however, patients receiving OMT had a lower risk of all‐cause hospital readmission (hazard ratio, 0.89; 95% confidence interval, 0.84–0.95). CONCLUSIONS: There is wide variation in the use of OMT in patients with nonobstructive coronary artery disease, the major driver of which is differences in baseline medication use.