or improving quality, according to new research.
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“Our conclusion that the MSSP was not associated with improvements in spending, quality, or most measures of hospital use differ from that of previous evaluations of Medicare ACOs,” Adam Markovitz, of the University of Michigan, Ann Arbor, and colleagues wrote in a new research report published in Annals of Internal Medicine.
“Our instrumental variable model addresses selection effects not directly captured in previous evaluations,” the researchers continued.
To illustrate the point, the researchers found an association between MSSP and spending when using an adjusted longitudinal model (change, –$118; 95% confidence interval, –$151 to –$85 per beneficiary per quarter), with savings coming from reductions in inpatient services, outpatient services, and skilled nursing facility charges.
However, when employing an instrumental variable model, there was not an association with changes in total spending (change, $5; 95%CI, –$51 to $62 per beneficiary per quarter.
“The instrumental variable estimate for spending differed significantly from the adjusted estimate,” Mr. Markovitz and colleagues noted. “Estimated savings were smaller in instrumental variable models than in adjusted models across each ACO cohort.”
Similar patterns were observed in quality observations.
“The MSSP was associated with improvements in all four clinical quality indicators in the adjusted longitudinal model but not in the instrumental variable model,” the authors wrote. “The MSSP was associated with modest decreases in all-cause hospitalizations and preventable hospitalizations in the longitudinal model but not in the instrumental variable model.”
Overall, the authors noted that the results “challenge the view that MSSP ACOs have lowered spending and improved quality; they indicate that savings by MSSP ACOs may be driven by nonrandom exit of high-cost clinicians and their patient panels from this voluntary program.”
Indeed, the report states that removing “high-cost clinicians from ACO contracts could have large effects on spending estimates and may contribute to reported findings that MSSP savings grow over time.”
Primary sources of funding for the research included the Horowitz Foundation for Social Policy, Agency for Healthcare Research and Quality, and the National Institute on Aging. No relevant disclosures were made by the authors.
SOURCE: Markovitz A et al. Ann Intern Med. 2019 Jun 18. doi: 10.7326/M18-2539.