Outcomes for hospitals participating in more- and less-mature ACOs

This study examines the impact of accountable care organization (ACO) maturity on inpatient costs, quality of care, and patient safety for hospitals participating in ACOs initiated by CMS relative to nonparticipants.

Quasi-experimental evaluation of hospitals before and after joining a CMS ACO using a difference-in-differences design during the period from 2010 to 2013.

Propensity score-matched groups of hospitals were used to estimate the combined effects of ACO maturity and CMS ACO participation on inpatient costs, quality, and patient safety outcomes. Total treatment costs, mortality rates for 4 common conditions, and 4 perioperative adverse events were investigated. Analyses were based on state-level data from the Healthcare Cost and Utilization Project.

We matched 121 CMS ACO-participating hospitals and 853 nonparticipating hospitals. Hospitals with an ACO maturity score of 0 had significantly worse acute myocardial infarction mortality and perioperative pulmonary embolism or deep vein thrombosis rates than nonparticipants. These differences were no longer significant with increasing ACO maturity. Higher ACO maturity was associated with significant improvements in accidental punctures and lacerations among hospital CMS ACO participants. No other significant trends were observed.

Findings suggest a potential positive effect of hospital CMS ACO participation with increasing maturity. However, use of early ACO data, a short follow-up period, and other limitations hindered the ability to identify significant trends. Nonetheless, ACO maturity scores and new outcome measures may offer a promising approach for tracking the long-term impact of hospital ACO participation in future research and policy evaluations.