How well do hospital mortality rates reported in the New York State CABG report card predict subsequent hospital performance?

Abstract

Background: The use of mortality report cards as the basis for hospital choice assumes that a hospital's current performance is predicted by its past performance.

Objective: To assess the accuracy of hospital risk-adjusted mortality rates reported in the New York State (NYS) coronary artery bypass graft (CABG) report card for predicting subsequent hospital mortality.

Methods: We performed a retrospective study based on hospital mortality measures for CABG surgery (n = 37 hospitals) in NYS, which are publicly reported by the NYS Department of Health. Feasible generalized least squares was used to examine the association between a hospital's past quality ranking (high-quality, intermediate-quality, low-quality) and its subsequent performance, as measured using the ratio of the observed-to-expected mortality rate (O-to-E ratio).

Results: Hospitals identified as low-mortality hospitals using 2-year-old data had subsequent O-to-E ratios that were 16.8% lower (95% confidence interval, 8.9-24.8; P < 0.001) than average-mortality hospitals, whereas hospitals identified as high-mortality hospitals had subsequent O-to-E ratios that were 31.8% higher (95% confidence interval, 3.69-59.9; P < 0.05) compared with average-mortality hospitals. Hospitals identified as high-mortality hospitals using 3-year-old data were indistinguishable from average-mortality hospitals.

Conclusion: Hospital ranking based on 2-year-old data is a strong predictor of future performance. Report cards based on 3-year-old data may not be useful for identifying low-performance hospitals. We recommend that the CABG report cards in NYS should be based on 2-year-old data, as opposed to the current practice of basing them on either 2- or 3-year-old data.