Accountable Care Organizations Don’t Always Boost Medication Adherence

Accountable Care Organizations Don’t Always Boost Medication Adherence
Stephanie Swanson, Pharm.D., North Memorial Health Northeast Clinic

Background: Accountable care organizations (ACOs) in the Medicare Shared Savings Program (MSSP) under the Affordable Care Act (ACA) are evaluated on performance through a variety of quality measures. Through 2014, almost half of these measures focused on cardiovascular disease and diabetes, specifically on disease control and medication use. Medication adherence has been identified as a tool to improve these measures as prescription drug spending is not included in the MSSP financial calculation.

Objective: To evaluate if the MSSP has been associated with changes in medication use or adherence for patients with cardiovascular disease or diabetes within ACOs. 

Study Design: Data from Medicare claims and enrollment files from 2009 to 2014 were analyzed for a 20% sample of fee-for-service beneficiaries. A total of six drug classes (statins, angiotensin-converting enzymes and angiotensin II receptor blockers, beta blockers, thiazide diuretics, calcium channel blockers, and metformin) were evaluated for proportion of days covered (PDC) by filled prescriptions for any beneficiary that had at least one prescription filled of the identified drug classes during the time frame. The denominator for the PDC was 365 days or the number of days remaining in the year after the first prescription fill. The numerator was the total days of drugs in the class supplied in the year. A difference-in-difference approach and linear regression was used to compare the changes in medication use and adherence between ACO beneficiaries and those with local non-ACO providers. Differential changes were estimated separately for cohorts of ACOs entering the MSSP in 2012, 2013, and 2014. 

Results: Overall, differential changes in medication use and adherence between the groups in all six drug classes were minimal and not statistically significant. There was a slight increase in thiazides among beneficiaries with hypertension in the 2013 entry cohort (adjusted differential change, 0.5 percentage point [95% CI 0.1-0.8 percentage points). There were also no significant differential changes in PDC, except for a slight increase in the PDC for beta blockers in the 2012 entry cohort (adjusted differential change, 0.3 percentage point; [95% CI 0.1-0.5 percentage points]) and metformin in the 2012 and 2013 cohorts (adjusted differential change, 0.5 percentage point; [95% CI 0.1-0.9 percentage points] for both groups). 

Conclusions: The investigators concluded that at this time, exposure to the MSSP has not been associated with meaningful changes in medication use or adherence among patients with cardiovascular disease and diabetes. Further studies need to be conducted to identify which components are most contributing to the benefit of ACOs and furthermore, understand the steps to success of these programs.


McWilliams JM, Najafzadeh M, Shrank WH, Polinski JM. Association of changes in medication use and adherence with accountable care organization exposure in patients with cardiovascular disease or diabetes. JAMA. July 2017. doi:10.1001/jamacardio.2017.2172.