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Prevalent But Moderate Variation Across Small Geographic Regions in Patient Nonadherence to Evidence-based Preventive Therapies in Older Adults After Acute Myocardial Infarction

Fang, Gang PharmD, MS, PhD*; Robinson, Jennifer G. MD, MPH; Lauffenburger, Julie PharmD*; Roth, Mary T. PharmD, MHS*; Brookhart, Maurice Alan PhD

doi: 10.1097/MLR.0000000000000050
Original Articles

Background: Patient long-term adherence to β-blockers, HMG-CoA reductase inhibitors (statins), and angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs) after acute myocardial infarction (AMI) is alarmingly low. It is unclear how prevalent patient adherence may be across small geographic areas and whether this geographic prevalence may vary.

Methods: This is a retrospective cohort study using Medicare service claims files from 2007 to 2009 with Medicare beneficiaries 65 years and above who were alive 30 days after the index AMI hospitalization between January 1, 2008 and December 31, 2008 (N=85,017). The adjusted proportions of patients adherent to β-blockers, statins, and ACEIs/ARBs, respectively, in the 12 months after discharge across the 306 Hospital Referral Regions (HRRs) were measured and compared by control chart. The intracluster correlation coefficient (ICC) and the additional prediction power from this small-area variation on individual patient adherence were assessed.

Results: The adjusted proportion of patients adherent across HRRs ranged from 58% to 74% (median, 66%) for β-blockers, from 57% to 67% (median, 63%) for ACEIs/ARBs, and from 58% to 73% (median, 66%) for statins. The ICC was 0.053 (95% CI, 0.043–0.064) for β-blockers, 0.050 (95% CI, 0.039–0.061) for ACEIs/ARBs, and 0.041 (95% CI, 0.031–0.052) for statins. The adjusted proportion of patients adherent across HRRs increased the c-statistic by 0.01–0.02 (P < 0.0001).

Conclusions: Nonadherence to evidence-based preventive therapies post-AMI among older adults was prevalent across small geographic regions. Moderate small-area variation in patient adherence exists.

Supplemental Digital Content is available in the text.

*Division of Pharmaceutical Outcomes and Policy, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC

Department of Epidemiology, Division of Cardiology, College of Public Health, College of Medicine, University of Iowa, Iowa City, IA

Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC

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The study was approved by the Institutional Review Boards of the University of North Carolina at Chapel Hill.

G.F. was supported by the American Heart Association (AHA) National Clinical Research Program (10CRP2610053) for this study. M.A.B. received unrestricted research support from Amgen and has served as a scientific advisor for Amgen, Pfizer, and Rockwell Medical (honoraria declined, donated, or paid to institution). He has received consulting fees from Crimson Health, DaVita Clinical Research, the Foundation for the National Institutes of Health, and World Health Information Consultants. J.G.R. received research grants awarded to the University of Iowa from Abbott, Daiichi-Sankyo, Esperion, Glaxo-Smith Kline, and Merck. J.L. receives support from the National Institute of Nursing Research (T32NR008856).

The authors declare no conflict of interest.

Reprints: Gang Fang, PharmD, MS, PhD, Division of Pharmaceutical Outcomes and Policy, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, 2202 Kerr Hall, Chapel Hill, NC 27599-7517. E-mail:

© 2014 by Lippincott Williams & Wilkins.