Reevaluating Congenital Heart Surgery Center Performance Using Operative Mortality

Abstract

Background: The Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) provides observed-to-expected (O/E) operative mortality ratios to more than 100 congenital heart centers in North America. We compared the current approach for estimating O/E ratios to approaches incorporating information on diagnosis as moderators of procedures, other unused risk factors, and additional variation in confidence interval construction to characterize center performance.

Methods: Bayesian additive regression trees (BART) and lasso models linked operative mortality to diagnosis-procedure categories, procedure-specific risk factors, and syndromes/abnormalities. Bootstrapping accounted for variation in the STS-CHSD (STS bootstrap) and lasso CIs. We compared O/E estimates, interquartile range of CI widths, and concordance of center performance categorizations (worse-than-, as-, or better-than-expected mortality) of the new approaches to the STS-CHSD.

Results: In 110 surgical centers including 98,822 surgical operative encounters, there were 2818 (2.85%) operative mortalities (center range, 0.37%-10%). Compared with the STS-CHSD, BART- and lasso-estimated O/E ratios varied more and had narrower confidence intervals (interquartile range of confidence interval: STS-CHSD = 1.11, STS bootstrap = 0.98; lasso = 0.80; BART = 0.96). Concordance of performance categorization with the STS-CHSD ranged from 84% (lasso) to 91% (STS Bootstrap); more than 70% of discordant centers improved categories. Discordant centers had smaller volumes, fewer operative mortalities, and treated more patients with congenital lung abnormalities.

Conclusions: Relative to the STS-CHSD, up to 16% of hospitals changed performance categories, most improving performance. Given the significance of quality reports for congenital heart centers, inclusion of additional risk factors and unaddressed variation should be considered.