Determinants of variations in initial treatment strategies for stable XXXX .

@entity1 @entity951 @entity741
BACKGROUND: The ratio of revascularization to medical therapy (referred to herein as the revascularization ratio) for the initial treatment of stable @entity741 varies considerably across hospitals. We conducted a comprehensive study to identify @entity1 , physician and hospital factors associated with variations in the revascularization ratio across 18 cardiac centres in the province of Ontario. We also explored whether clinical outcomes differed between hospitals with high, medium and low ratios. METHODS: We identified all @entity1 in Ontario who had stable @entity741 documented by index angiography performed between Oct. 1, 2008, and Sept. 30, 2011, at any of the 18 cardiac centres in the province. We classified @entity1 by initial treatment strategy (medical therapy or revascularization). Hospitals were classified into equal tertiles based on their revascularization ratio. The primary outcome was all-cause mortality. @entity1 followup was until Dec. 31, 2012. Hierarchical logistic regression models identified predictors of revascularization. Multivariable Cox proportional hazards models, with a time-varying covariate for actual treatment received, were used to evaluate the impact of the revascularization ratio on clinical outcomes. RESULTS: Variation in revascularization ratios was twofold across the hospitals. @entity1 factors accounted for 67.4% of the variation in revascularization ratios. Physician and hospital factors were not significantly associated with the variation. Significant @entity1 -level predictors of revascularization were history of smoking, multivessel disease, high-risk findings on noninvasive stress testing and more severe symptoms of @entity951 (v. no symptoms). Treatment at hospitals with a high revascularization ratio was associated with increased mortality compared with treatment at hospitals with a low ratio (hazard ratio 1.12, 95% confidence interval 1.03-1.21). INTERPRETATION: Most of the variation in revascularization ratios across hospitals was warranted, in that it was driven by @entity1 factors. Nonetheless, the variation was associated with potentially important differences in mortality.
