Assessing providers of coronary revascularization: A method for peer review organizations

Objectives. Current methods to evaluate quality of care are usually limited to reviews of individual cases or comparisons of hospital mortality rates. We present an alternative method that compares complication rates adjusted for patient characteristics. Methods. Detailed clinical data that were specifically designed for quality comparisons of providers of revascularization procedures were abstracted from the medical records of 1998 Medicare patients, in 16 hospitals, who had coronary artery bypass surgery and 2091 patients, in 16 hospitals, who had angioplasty. Providers were ranked on the basis of an unadjusted risk, a risk adjusted for detailed clinical information, and a risk adjusted only for patient comorbidities. Results. Complication rates differed significantly and substantially among the hospitals. Clinical adjustment changed the hospital rankings for the bypass surgery hospitals, but not for the angioplasty hospitals. Adjustment for comorbidities did not affect hospital rankings for either procedure. Conclusions. When sample sizes are limited, adverse outcome rates may be a more sensitive measure of quality of care than mortality rates. Rates that are unadjusted or adjusted only for comorbidities may be inadequate for evaluating some providers of bypass surgery.