Apparent truth about congenital diaphragmatic hernia: a population-based database is needed to establish benchmarking for clinical outcomes for CDH

BACKGROUND: The authors hypothesize that recent single or multiinstitution-based reports of improved survival of congenital diaphragmatic hernia (CDH) patients are biased by patient selection, practice, and referral patterns. Here the authors report a population-based analysis of the clinical outcomes of CDH in the province of Ontario for 1996. METHODS: A retrospective analysis of cross-sectional data from the Bureau of Vital Statistics of Ontario and all 5 pediatric surgical institutions in Ontario for 1996 was performed. RESULTS: Twenty-four CDH-associated deaths were registered in Canada in 1996. Fourteen of 24 occurred in Ontario (58.3%). Of 30 institutionally identified CDH in Ontario, 8 patients died (26.7%). CDH-associated infant mortality rate was 6.6 of 100,000 live births in Canada compared with 10 of 100,000 live births for Ontario (Relative risk, 1.4; confidence interval, 0.5, 3.7; P >.01). Neonatal death (<28 postnatal days) accounted for the majority, 13 of 14 (92.8%) of deaths. Six of 14 (42.9%) CDH-associated deaths, however, were not accounted by the institutional-based reporting. In addition, institutional-based survival rates for CDH varied from 62.5% to 100%. CONCLUSIONS: Our results indicate the existing bias associated with institution-based reporting and database of CDH. The "hidden mortality" associated with CDH is still present. A population-based database is needed to establish the benchmarking for management of CDH.