Current assessment of mortality rates in congenital cardiac surgery

The purpose of this study is to evaluate whether published and widely quoted mortality rates for pediatric cardiac surgery accurately reflect current expectations. Our hypotheses are that (1) mortality rates at high-quality pediatric cardiac programs are lower than published national results despite (2) a change in case mix with a shift away from low complexity operations.

We requested data for all pediatric cardiac surgical procedures performed between 2001 and 2004 at 29 Congenital Heart Surgeon's Society (CHSS) member institutions (using CHSS as a surrogate for recognized high quality). Procedures were categorized by Risk Adjustment for Congenital Heart Surgery, version 1 (RACHS-1) category. In-hospital mortality rates for each category were calculated and compared with those in the 2002 manuscript of Jenkins and colleagues.

We received data for 16,805 procedures from 11 institutions. In all, 12,672 operations (76%) could be placed into RACHS-1 categories. Overall in-hospital mortality for categorized operations was 2.9% and was most related to case mix. There was a significant decrease in the percentage of category 1 operations, and there were significant increases in category 2, 4, and 6 operations. There were significant decreases in category 2, 3, 4, and 6 mortality rates (Jenkins 2002 [CHSS]): (1) 0.4% [0.7%], (2) 3.8% [0.9%], (3) 8.5% [2.7%], (4) 19.4% [7.7%], (5) not applicable, and (6) 47.7% [17.2%]. There was no significant association between hospital surgical volume and mortality.

This outcomes "footprint" suggests that we could hold ourselves accountable to higher benchmarks than those reflected by some published standards. Mortality rates declined, despite an increase in case mix complexity. The lack of association between hospital surgical volume and mortality suggests that other factors determine outcomes at high-quality institutions. In addition to continually validating our expectations for treatment, future research needs to identify these factors by understanding the system of care and identifying process measures that influence outcomes.