The association between medicare accountable care organization enrollment and breast, colorectal, and prostate cancer screening.

Background Despite the rapid diffusion of accountable care organizations (ACOs), the effect of ACO enrollment on cancer diagnosis, treatment, and survivorship remains unknown. The objective of this study was to determine whether Medicare Shared Savings Program (MSSP) ACO enrollment was associated with changes in screening for breast, colorectal, and prostate cancers. Methods The authors built a cohort of Medicare beneficiaries from 2006 through 2014 comprising 39,218,652 person-years of observation before and 17,252,345 person-years of observation after MSSP enrollment. The Centers for Medicare & Medicaid Services attribution methodology was recapitulated; and screening services were identified for breast, colorectal, and prostate cancer, implementing both sensitive and specific definitions of cancer screening. Adjusted difference-in-differences analyses were performed using linear regression to characterize changes in annual screening rates after ACO enrollment relative to contemporaneous changes in a non-ACO control group of Medicare beneficiaries. Results Medicare beneficiaries attributed to ACO-enrolled providers had higher rates of breast, colorectal, and prostate cancer screening before enrollment. A 1.8% relative reduction in breast cancer screening was observed among women attributed to ACO providers (P < .0001), a 2.4% relative increase was observed in colorectal cancer screening (P = .0259), and a 3.4% relative reduction was observed in prostate cancer screening among men attributed to ACO providers (P = .0025) compared with contemporaneous changes in non-ACO controls. Conclusions Small-magnitude reductions were observed in breast and prostate cancer screening rates, and a small increase was observed in colorectal cancer screening associated with ACO enrollment. Although ACO enrollment does not appear to drive wholesale changes in cancer screening, small differences may map to meaningful changes in the epidemiology of screen-detected cancers among Medicare beneficiaries. (c) 2018 American Cancer Society.