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Brief Report
July 12, 2017

Association of Changes in Medication Use and Adherence With Accountable Care Organization Exposure in Patients With Cardiovascular Disease or Diabetes

Author Affiliations
  • 1Department of Health Care Policy, Harvard Medical School, Boston, Massachusetts
  • 2Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts
  • 3Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women’s Hospital, Boston, Massachusetts
  • 4Health Plan, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
  • 5Department of Internal Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
  • 6CVS Health, Woonsocket, Rhode Island
JAMA Cardiol. Published online July 12, 2017. doi:10.1001/jamacardio.2017.2172
Key Points

Question  Has the Medicare Shared Savings Program been associated with changes in medication use or adherence for patients with cardiovascular disease or diabetes in participating accountable care organizations?

Findings  In this population-based study of Medicare beneficiaries from before the start of accountable care organization contracts to 2014, ranging from approximately 4.5 million to 10.8 million person-years, depending on drug class, differential changes in the use of and adherence to common antihypertensive, lipid-lowering, and hypoglycemic medications were minimal for accountable care organization patients vs patients of non–accountable care organization providers.

Meaning  Through its third year of operation, the Medicare Shared Savings Program has not meaningfully increased the use of or adherence to medications that improve outcomes for patients with cardiovascular disease or diabetes.

Abstract

Importance  Many of the quality measures used to assess accountable care organization (ACO) performance in the Medicare Shared Savings Program (MSSP) focus on disease control and medication use among patients with cardiovascular disease and diabetes. To date, the association between participation in the MSSP by provider organizations and medication use or adherence among their patients with cardiovascular disease or diabetes has not been described.

Objective  To assess the association between exposure to the MSSP and changes in the use of and adherence to common antihypertensive, lipid-lowering, and hypoglycemic medications.

Design, Setting, and Participants  Fee-for-service Medicare claims from January 1, 2009, to December 31, 2014, were used to conduct difference-in-differences comparisons of changes for ACO-attributed beneficiaries from before the start of ACO contracts to 2014 with concurrent changes for beneficiaries attributed to local non-ACO providers (control group). A random 20% sample of Medicare beneficiaries contributing 4 482 168 to 10 849 224 beneficiary-years for analysis from 2009 to 2014, depending on the drug class, was examined. Differential changes were estimated separately for cohorts of ACOs entering the MSSP in 2012, 2013, and 2014. Data analysis was conducted from November 1, 2016, to April 5, 2017.

Exposures  Patient attribution to an ACO after entry into the MSSP.

Main Outcomes and Measures  Any use (at least 1 prescription fill) and proportion of days covered (PDC), a standard claims-based measure of adherence, assessed for each of 6 drug classes: statins, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, β-blockers, thiazide diuretics, calcium channel blockers, and metformin.

Results  Differences in patient characteristics between the MSSP and control group were generally small after geographic adjustment and changed minimally from the precontract period to 2014. There were no significant differential changes in medication use from the precontract period to 2014 for any cohort of MSSP ACOs in any drug class, except for a slight differential increase in the use of 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; or 1.5% of the overall percentage using thiazides [33.4%], P = .01). Similarly, there were no significant differential changes in PDC among beneficiaries with at least 1 prescription fill, except for slight differential increases in the PDC for β-blockers in the 2012 entry cohort (adjusted differential change, 0.3 percentage point; 95% CI, 0.1-0.5 percentage points; or 0.4% of the mean PDC [82.3%], P = .003) and for metformin in the 2012 and 2013 cohorts (adjusted differential change, 0.5 percentage point; 95% CI, 0.1-0.9 percentage points; or 0.6% of the mean PDC [78.2%], P = .01 for both).

Conclusions and Relevance  Exposure to the MSSP has not been associated with meaningful changes in medication use or adherence among patients with cardiovascular disease and diabetes.

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