Early impact of Medicare accountable care organizations on cancer surgery outcomes.

BACKGROUND: Accountable care organizations (ACOs) were established to improve care and outcomes for beneficiaries requiring highly coordinated, complex care. The objective of this study was to evaluate the association between hospital ACO participation and the outcomes of major surgical oncology procedures.

METHODS: This was a retrospective cohort study of Medicare beneficiaries older than 65 years who were undergoing a major surgical resection for colorectal, bladder, esophageal, kidney, liver, ovarian, pancreatic, lung, or prostate cancer from 2011 through 2013. A difference-in-differences analysis was implemented to compare the postimplementation period (January 2013 through December 2013) with the baseline period (January 2011 through December 2012) to assess the impact of hospital ACO participation on 30-day mortality, complications, readmissions, and length of stay (LOS).

RESULTS: Among 384,519 patients undergoing major cancer surgery at 106 ACO hospitals and 2561 control hospitals, this study found a 30-day mortality rate of 3.4%, a readmission rate of 12.5%, a complication rate of 43.8%, and a prolonged LOS rate of 10.0% in control hospitals and similar rates in ACO hospitals. Secular trends were noted, with reductions in perioperative adverse events in control hospitals between the baseline and postimplementation periods: mortality (percentage-point reduction, 0.1%; P = .19), readmissions (percentage-point reduction, 0.4%; P = .001), complications (percentage-point reduction, 1.0%; P < .001), and prolonged LOS (percentage-point reduction, 1.1%; P < .001). After accounting for these secular trends, this study identified no significant effect of hospital participation in an ACO on the frequency of perioperative outcomes (difference-in-differences estimator P values, .24-.72).

CONCLUSIONS: Early hospital participation in the Medicare Shared Savings Program ACO program was not associated with greater reductions in adverse perioperative outcomes for patients undergoing major cancer surgery in comparison with control hospitals. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2739-2746. © 2016 American Cancer Society.