Medicare Accountable Care Organizations Reduce Spending on Surgery

Surgical care among older adults is costly. While Medicare accountable care organizations (ACOs) are designed around primary care, there are reasons to believe that participation may also affect spending on surgery. This study examines the impact that Medicare ACO alignment has on spending for inpatient and outpatient surgical care.

We conducted a retrospective cohort study using national Medicare claims (2008 through 2015). Among a 20% random sample of beneficiaries, we identified adults 65 years of age and older enrolled in fee-for-service Medicare, distinguishing between those aligned and unaligned with a Medicare ACO. We then measured payments for surgical services made on their behalf. Finally, we fit multivariable regression models to evaluate the association between ACO alignment and spending for inpatient and outpatient surgical care.

We identified 37,249,845 beneficiary-year observations, of which 2,950,188 (7.9%) were aligned with a Medicare ACO. After adjustment for patient factors, ACO alignment was associated with $181 [95% confidence interval (CI), -$243 to -$118; P <0.001] lower spending per beneficiary-year. ACO alignment was associated with 2.9% fewer inpatient surgical episodes per year [incidence rate ratio (IRR), 0.97; 95% CI, 0.96 to 0.98; P <0.001] but 2.3% more outpatient episodes per year (IRR, 1.02; 95% CI, 1.02 to 1.03; P <0.001). Among inpatient surgical episodes, average payments were $956 lower for ACO aligned beneficiaries (95%CI -$1218 to -$694, P <0.001).

ACO alignment was associated with savings on surgical care. These savings resulted from increased outpatient surgery and reduced use of inpatient surgery as well as reduced spending per inpatient surgical episode. Greater focus on surgical care may improve the ability of ACOs to control healthcare spending.