Ryan P. Barbaro, Folafoluwa O. Odetola, Kelley M. Kidwell, Matthew L. Paden, Robert H. Bartlett, Matthew M. Davis, Gail M. Annich

Rationale: Recent pediatric studies suggest a survival benefit exists for higher volume extracorporeal membrane oxygenation (ECMO) centers. Objective: To determine if higher annual ECMO patient volume is associated with lower case-mix-adjusted hospital mortality rate. Methods: We retrospectively analyzed an international registry of ECMO support from 1989-2013. Patients were separated into three age groups: neonatal (0-28 days), pediatric (29 days to <18 years), and adult (≥18 years). The measure of hospital ECMO volume was age group specific and adjusted for patient-level case-mix and hospital-level variance using multivariable hierarchical logistic regression modeling. The primary outcome was death prior to hospital discharge. A subgroup analysis was conducted for 2008-2013. Measurements and Main Results: From 1989-2013, 290 centers provided ECMO support to 56,222 patients (30,909 neonates; 14,725 children; 10,588 adults). Annual ECMO mortality rates varied widely across ECMO centers: the interquartile range was 18-50% for neonates, 25-66% for pediatrics, and 33-92% for adults. For 1989-2013, higher age group specific ECMO volume was associated with lower odds of ECMO mortality for neonates and adults, but not for pediatric cases. In 2008-2013, the volume-outcome association remained statistically significant only among adults. Patients receiving ECMO at hospitals with >30 adult annual ECMO cases had significantly lower odds of mortality (adjusted odds ratio=0.61; 95% confidence interval 0.46-0.80) compared with adults receiving ECMO at hospitals with <6 annual cases. Conclusions: In this international, case-mix-adjusted analysis, higher annual hospital ECMO volume was associated with lower mortality in 1989-2013 for neonates and adults; the association among adults persisted in 2008-2013.