The effect of surgical case volume on outcome after the Norwood procedure

We analyze the effect of surgical case volume on the survival of infants with hypoplastic left heart syndrome who underwent stage I surgical palliation (the Norwood procedure). The purpose of our study was to understand more clearly the relative effects of institution and surgeon experience on patient outcome.

Using the Pediatric Health Information System database belonging to the pediatric hospital members of the Child Health Corporation of America, we identified newborn infants (< 30 days old on admission) from 1998 through 2001 admitted with the diagnosis of hypoplastic left heart syndrome. Stepwise multiple regression analysis was used to examine the association between both institutional and surgeon case volume with 28-day survival after the Norwood procedure.

Twenty-nine hospitals and 87 surgeons performed 801 Norwood procedures during the study period. In the 4 of 29 institutions that averaged 1 or more Norwood procedures per month during the study period, survival averaged 78%. The remaining 25 institutions averaged 1 Norwood procedure every 9.6 weeks, with a survival of 59%. Data analysis revealed that higher institutional volume (P = .02) but not the number of cases performed by surgeons (P = .13) increased survival after the Norwood procedure. There was no such association with average length of stay in survivors or the time to mortality in nonsurvivors.

Survival after the Norwood procedure is associated with institutional Norwood procedure volume but not with individual surgeon case volume, suggesting the need for improvements in institutional-based approaches to the care of children with hypoplastic left heart syndrome and the need for establishing regional referral centers for such high-risk procedures to improve patient survival.