Optimization of rectal cancer surgery outcomes in the United States: the influence of hospital volume on rates of sphincter preservation before and after practice standardization.

Background: Multiple studies have found hospital-level proctectomy volumes to be associated with quality-of-care outcomes. The Consortium for Optimizing the Surgical Treatment of Rectal Cancer (OSTRiCh) was created in 2011 to spearhead quality standards. We investigated associations of facility-level proctectomy volumes with sphincter-preservation rates, as a rectal cancer surgery quality indicator, across the United States during 14 years before (1998-2011) and 3 years (2012-2014) into the OSTRiCh consortium. Methods: Low anterior and abdominoperineal resections for rectal cancer were identified from the National Inpatient Sample. Multivariable logistic regression with restricted cubic splines was used to test the association between annual proctectomy volumes per hospital and odds of sphincter-preserving resection. Results: We sampled 54,089 proctectomies performed during 1998 to 2014 in 5029 facilities that were 91.9% urban, 66.8% large, and 57.3% teaching hospitals. Recipients were 58.1% male, 70.6% White, 6.6% Black, 46.2% on Medicare, and 43.4% on commercial insurance. Mean age was 63.8 (±12.9) years. Across all study years, an optimum facility-level annual threshold of 30 proctectomies minimized sphincter-sacrificing resections. Analyses restricted to 2012 to 2014 suggested a lower annual optimum of 10 proctectomies per hospital. Higher facility-level proctectomy volume was associated with greater risk-adjusted odds of sphincter preservation in pre-OSTRiCh but not intra-OSTRiCh years. Conclusion: The association between higher facility-level proctectomy volume and sphincter preservation odds during prestandardization years had weakened by the early intra-OSTRiCh years.