Association between anesthesiology volumes and early and late outcomes after cystectomy for bladder cancer: A population-based study
BACKGROUND: Hospital and surgeon volume are related to postoperative complications and long-term survival after radical cystectomy. Here, we describe the relationships between these provider characteristics and anesthesiologist volumes on early and late outcomes after radical cystectomy for bladder cancer. METHODS: Records of treatment and surgical pathology reports were linked to the population-based Ontario Cancer Registry to identify all patients with radical cystectomy in Ontario during 1994 to 2008. Volume was divided into quartiles and determined on the basis of mean annual number of hospital/surgeon/anesthesiologist radical cystectomy cases during a 5-year study period. A composite anesthesiologist volume also was used and defined as major colorectal procedures in addition to radical cystectomy given the similar complexity of these cases. Logistic and Cox proportional hazards regression models were used to explore the associations between volume and outcomes while adjusting for potential patient-, disease-, and system-related confounders. The primary outcomes were postoperative readmission rates, postoperative mortality, and 5-year survival. RESULTS: The study included 3585 patients with radical cystectomy between 1994 and 2008. Median annual anesthesiologist radical cystectomy volume was 1 (maximum 8.8 cases/year); lowest volume quartile (Q1) <0.6 cases/year and highest volume quartile (Q4) >1.4 cases/year. The median annual composite anesthesiologist volume was 9 radical cystectomy and colorectal cases (Q1 [range 0.2-6.4 cases/year], Q4 [range 11.8-29.2 cases/year]); subsequent analyses used this composite volume. Anesthesiologist volume was associated with readmission rates at 30 days (P =.02, Q1 mean = 27% vs Q4 mean = 21%) and at 90 days (P =.01, Q1 mean = 39% vs Q4 mean = 31%). In multivariable analysis, including the adjustment for surgeon and hospital volume, the cohort of anesthesiologists who performed the lowest volume of cases annually (Q1) was associated with greater rates of readmission at 30 days (OR 1.36, 95% confidence interval [CI], 1.09-1.71, P =.04) and at 90 days (OR 1.36, 95% CI, 1.11-1.66, P =.03). Anesthesiologist volumes were not associated with postoperative mortality or long-term survival. CONCLUSIONS: Anesthesiologist case volume for radical cystectomy was low, reflecting the lack of subspecialization in urologic procedures in routine clinical practice. Lower volume anesthesia providers were associated with higher readmission rates after radical cystectomy. Further studies are needed to validate this finding and to identify the processes that may explain an association between provider volume and patient outcome. © 2017 International Anesthesia Research Society.