Medicare ACO savings may not be driven by interventions targeting high-risk patients, study finds

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ACO savings may not be tightly linked to programs for high-risk patients, according to a new study.

Savings for Medicare Shared Savings Program accountable care organizations may not be driven by better coordinated care for high-risk patients—one of the program's central goals—according to a new study. 

Researchers at Harvard Medical School examined a random 20% sample of Medicare fee-for-service beneficiaries between 2009 and 2014, with about 17% enrolled in an MSSP ACO, according to the study published in Health Affairs. 

The researchers divided the ACO patients into enrollment cohorts for 2012, 2013 and 2014. They found that less than half of spending reductions in the 2012 MSSP cohort could be attributed to interventions targeting high-risk patients. 

Spending decreases were greatest among high-risk patients for the 2012 group, according to the study, but decreases were similarly significant among the other patients, a much larger group. Spending reductions for high-risk patients totaled about 38% of aggregate savings, about $686 per high-risk beneficiary. 

RELATED: How NYC Health + Hospitals found ACO success, reducing Medicare costs and earning millions in savings 

In addition, MSSP participation was not linked to overall decreased hospitalizations for ambulatory care-sensitive conditions, and hospitalization rates actually increased modestly but significantly for the 2012 and 2014 cohorts, according to the study. 

"These findings are consistent with care coordination and management efforts, on average, either having minimal effects on the risk of hospitalization or acting to increase the use of inpatient care by improving access and filling gaps in care for high-needs patients," the researchers said.

The findings have policy implications for the ACO model, according to the study. Strategies for quality improvement and for spending reduction are likely more distinct than the model currently accounts for, so a greater focus on patients' experiences and outcomes could better lead to quality improvement than current utilization-based metrics like admissions.

RELATED: 3 traits of successful ACOs—A focus on internal culture, population health and continuous improvement 

The findings also suggest that policymakers should take a second look at how primary care doctors who practice in ACOs are paid, according to the researchers. Their care coordination efforts may not translate to major savings, and they may not be adequately compensated for that work.

Overall, MSSP has earned significant savings, according to data released by the Centers for Medicare & Medicaid Services. Program ACOs saved $652 million last year, with 56% of participants reducing their expenditures.