Evidence-based referral results in significantly reduced mortality after congenital heart surgery

Objective. Significant interinstitutional variation in mortality after congenital heart surgery has been demonstrated. Noting an association between reduced mortality and higher volume, a center with a small annual case volume began in August 1998 to selectively refer to high-volume surgical centers based on published or "apparent" low mortality rates for specific cardiac lesions. This study was undertaken to evaluate the effect of evidence-based referral in this practice. Design, Setting, and Participants. A retrospective cohort comparison over a 10-year period for a small Midwestern pediatric cardiology practice. The institutional database was retrospectively reviewed for children (<18 years) undergoing surgery from August 1992 to July 2002. Data were divided into 3 time periods (August 1992 to July 1995, period 1; August 1995 to July 1998, period 2; and August 1998 to July 2002, period 3). Hospital discharge abstract data from 5 states (California, Illinois, Massachusetts, Pennsylvania, and Washington) in 1992, 1996, and 1998 provided contemporaneous benchmarks. Risk adjustment was performed using the Risk Adjustment in Congenital Heart Surgery-1 method. Risk category, age at surgery, prematurity, and major noncardiac structural anomaly were entered into a multivariate logistic regression model to compare in-hospital mortality adjusting for case-mix differences. Results. A total of 514 congenital heart surgical cases were identified from August 1992 to July 2002; 507 cases (98.6%) were assigned to a risk category and analyzed further. Unadjusted in-hospital mortality rates were 9.3% in period 1, 5.9% in period 2, and 1.3% in period 3. Unadjusted mortality rates for cases from benchmark data were 6.4% in 1992, 4.8% in 1996, and 3.7% in 1998. Risk adjusted mortality was comparable to the benchmark data in periods 1 and 2, but superior outcomes (odds ratio = 0.24) were demonstrated in period 3. Conclusions. Evidence-based referrals from a small-volume pediatric cardiac center to large-volume institutions resulted in a reduction in mortality after congenital heart surgery.