Volume-Outcome Relationships in Extracorporeal Membrane Oxygenation: Retrospective Analysis of Administrative Data...

This article seeks to understand whether a volume-outcome relationship exists in adult extracorporeal membrane oxygenation (ECMO). We examined primary administrative discharge data from the Pennsylvanian Health Care Cost Containment Council for all 2,948 consecutive adults treated with ECMO in Pennsylvania between January 1, 2007, and December 31, 2015. We used a well-fitting backwards stepwise logistic regression to obtain patient-level predicted mortality. Number of cases and risk-adjusted mortality was aggregated by calendar quarter and by hospital. Graphical and correlation analysis was used to understand the volume-outcome relationship, focusing separately on the impact of a hospital's current scale (annual volume of adult ECMO) and a hospital's cumulative experience (total cumulative volume of adult ECMO since starting operations). We found that more than 9 years, there was essentially no reduction in overall risk-adjusted mortality in the state. For individual hospitals, once institutions had as few as 50 cases' total experience or performed just 10 cases annually, there was no clear improvement in outcomes. Patients in hospitals with fewer than 50 cases ever performed appeared objectively less sick compared with patients in hospital with more experience. We conclude that there is little evidence of volume-outcome relationships in adult ECMO in this state, although we acknowledge that the absence of clinical chart data limits these conclusions.