Impact of medicare shared savings program accountable care organizations at screening mammography: A retrospective cohort study

Purpose: To evaluate the impact of accountable care organizations (ACOs) on use of screening mammography in the Medicare Shared Savings Program (MSSP), the largest valuebased reimbursement program in U.S. history. Materials and Methods: Institutional review board approval was waived, as the study used publicly available unidentifable data. Medicare data were retrospectively obtained for participating ACOs from 2012 to 2014. Baseline information and the ACO-20 measure (percentage of women aged 40-69 years who underwent screening mammography within 24 months) were obtained. Negative binomial regression models were used to evaluate baseline and longitudinal mammography use, with stratifed analyses performed for year of entry into the ACO, number of benefciaries, and geographic region. Results: A total of 333 ACOs with 5329831 Medicare benefciaries (mean size, 16006 benefciaries) participated in the MSSP. Screening use varied across ACOs (median, 63.0%; range, 8.8%-90.3%), with differences found across regions (use was highest in the Midwest [66.6%] and lowest in the South [58.2%], P =.038). A total of 208 ACOs reported longitudinal outcomes, with mean change in screening mammography use of +2.6% (range, 233.2% to +42.2%), with 128 (61.6%) ACOs reporting improvements (incidence rate ratio, 1.04; 95% confdence interval: 1.02, 1.07) (P =.002). No longitudinal differences in use were seen across regions (P =.078), year of entry (P =.902), number of benefciaries (P =.814), or total composite quality score (P =.324), nor was there a difference between ACOs that saved money and those that did not (P =.391). Conclusion: ACOs in the MSSP have produced small signifcant improvements in screening mammography use.