Comparing XXXX outcomes: The impact of low hospital case volume and case-mix adjustment.

@entity1 @entity694 @entity834
OBJECTIVE: When comparing performance across hospitals it is essential to consider the noise caused by low hospital case volume and to perform adequate case-mix adjustment. We aimed to quantify the role of noise and case-mix adjustment on standardized postoperative mortality and @entity834 ( @entity834 ) rates. METHODS: We studied 13  120 @entity1 who underwent @entity694 resection in 85 Dutch hospitals. We addressed differences between hospitals in postoperative mortality and @entity834 , using fixed (ignoring noise) and random effects (incorporating noise) logistic regression models with general and additional, disease specific, case-mix adjustment. RESULTS: Adding disease specific variables improved the performance of the case-mix adjustment models for postoperative mortality (c-statistic increased from 0.77 to 0.81). The overall variation in standardized mortality ratios was similar, but some individual hospitals changed considerably. For the standardized @entity834 rates the performance of the adjustment models was poor (c-statistic 0.59 and 0.60) and overall variation was small. Most of the observed variation between hospitals was actually noise. CONCLUSION: Noise had a larger effect on hospital performance than extended case-mix adjustment, although some individual hospital outcome rates were affected by more detailed case-mix adjustment. To compare outcomes between hospitals it is crucial to consider noise due to low hospital case volume with a random effects model.
