What Constitutes a "High-Volume" Hospital for Pancreatic Resection?

Background: Annual institution resection volume has been proposed for defining centers of excellence, with various cut-offs for defining "high-volume" centers used. This study aimed to define an objective, evidence-based operative volume threshold associated with improved postoperative outcomes after pancreatic resection. Study Design: This retrospective analysis of patients who underwent pancreatic resection in the Nationwide Inpatient Sample, a 20% representative sample of patients in the US between 1998 and 2003, was performed using multivariable logistic regression. Different models of annual hospital resection volume were analyzed and the goodness of fit of each "high-volume" model to postoperative mortality was compared through use of the pseudo r². Results: Based on analysis of 7,558 patients who underwent pancreatic resection, median annual institution resection volume was 15 (range 1 to 254), and overall in-hospital mortality was 7.6%. The best model of "high-volume" centers was an annual institution resection volume of 19 or more, as determined by goodness of fit (r² of 5.29%). But there was little difference in data variance explained between this best model and other "high-volume" models. The model without any volume variable had a goodness-of-fit r² of 3.57%, suggesting that volume explains less than 2% of data variance in perioperative death after pancreatic resection. Conclusions: Very little difference was observed in the explanatory powers of models of "high-volume" centers. Although volume has an important impact on mortality, volume cut-off is necessary but insufficient for defining centers of excellence. Volume appears to function as an imperfect surrogate for other variables, which may better define centers of excellence.