Volume outcomes of cystectomy--is it the surgeon or the setting?

ABSTRACT

PURPOSE: Hospital volume and surgeon volume are each associated with outcomes after complex oncological surgery. However, the interplay between hospital and surgeon volume, and their impact on these outcomes has not been well characterized. We studied the relationship between surgeon and hospital volume, and overall mortality after radical cystectomy. MATERIALS AND METHODS: The SEER (Surveillance, Epidemiology and End Results)-Medicare linked database was used to identify 7,127 patients with urothelial carcinoma of the bladder who underwent radical cystectomy from 1992 to 2006. Hospital volume and surgeon volume were expressed by tertile. The primary outcome measure was overall survival. Covariates included age, Charlson comorbidity index, stage, grade, node count, node density, number of positive nodes, urinary diversion and year of surgery. Multivariate analyses using generalized linear multilevel models were used to determine the independent association between hospital and surgeon volume and survival. RESULTS: When hospital volume or surgeon volume was included in the multivariate model, a significant volume-survival relationship was observed for each. However, when both were in the model, hospital volume attenuated the impact of surgeon volume on mortality while the significant hospital volume-mortality relationship persisted (HR 1.18, 95% CI 1.08-1.30, p <0.01). In addition, the adjusted 3-year probability of survival was significantly correlated with hospital volume in each distinct surgeon volume stratum while survival was not correlated with surgeon volume in each hospital volume stratum. CONCLUSIONS: After adjustment for patient and disease characteristics, the relationship between surgeon volume and survival after radical cystectomy is accounted for by hospital volume. In contrast, hospital volume remained an independent predictor of survival, suggesting that structure and process characteristics of high volume hospitals drive long-term outcomes after radical cystectomy.