(HealthDay News) — Medicare spending is down in year 1 of the Pioneer accountable care organization (ACO) program, according to a study published in the New England Journal of Medicine.

J. Michael McWilliams, MD, PhD, from Harvard Medical School in Boston, and colleagues compared Medicare spending for beneficiaries attributed to Pioneer ACOs (ACO group) with other beneficiaries (control group) before (2009 through 2011) and after (2012) the start of Pioneer ACO contracts. 

Spending was adjusted for geographic area and beneficiaries’ sociodemographic and clinical characteristics. Differential changes in spending were assessed for several subgroups of ACOs.

The researchers found that during the pre-contract period, adjusted Medicare spending and spending trends were similar in the ACO and control groups. In 2012, there was a change in the total adjusted per-beneficiary spending in the ACO group vs. the control group (−$29.2 per quarter; P=.007), representing a 1.2% savings. 

Greater savings were seen for ACOs with baseline spending above the local average vs. below the local average (P=.05 for interaction) and for those serving high-spending areas vs. low-spending areas (P=.04).

“Year one of the Pioneer ACO program was associated with modest reductions in Medicare spending,” the researchers wrote.


  1. MCWilliams JM et al. N Engl J Med. 2015;doi:10.1056/NEJMsa1414929.