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Changes in Use of Lipid-lowering Medications Among Black and White Dual Enrollees With Diabetes Transitioning From Medicaid to Medicare Part D Drug Coverage

Adams, Alyce S. PhD*; Madden, Jeanne M. PhD; Zhang, Fang PhD; Soumerai, Stephen B. ScD; Gilden, Dan MS; Griggs, Jennifer MD§; Trinacty, Connie M. PhD; Bishop, Christine PhD; Ross-Degnan, Dennis ScD

doi: 10.1097/MLR.0000000000000159
Original Articles

Background: The use of lipid-lowering agents is suboptimal among dual enrollees, particularly blacks.

Objectives: To determine whether the removal of restrictive drug caps under Medicare Part D reduced racial differences among dual enrollees with diabetes.

Research Design: An interrupted time series with comparison series design (ITS) cohort study.

Subjects: A total of 8895 black and white diabetes patients aged 18 years and older drawn from a nationally representative sample of fee-for-service dual enrollees (January 2004–December 2007) in states with and without drug caps before Part D.

Measures: We examined the monthly (1) proportion of patients with any use of lipid-lowering therapies; and (2) intensity of use. Stratification measures included age (less than 65, 65 y and older), race (white vs. black), and sex.

Results: At baseline, lipid-lowering drug use was higher in no drug cap states (drug cap: 54.0% vs. nondrug cap: 66.8%) and among whites versus blacks (drug cap: 58.5% vs. 44.9%, no drug cap: 68.4% vs. 61.9%). In strict drug cap states only, Part D was associated with an increase in the proportion with any use [nonelderly: +0.07 absolute percentage points (95% confidence interval, 0.06–0.09), P<0.001; elderly: +0.08 (0.06–0.10), P<0.001] regardless of race. However, we found no evidence of a change in the white-black gap in the proportion of users despite the removal of a significant financial barrier.

Conclusions: Medicare Part D was associated with increased use of lipid-lowering drugs, but racial gaps persisted. Understanding non–coverage-related barriers is critical in maximizing the potential benefits of coverage expansions for disparities reduction.

Supplemental Digital Content is available in the text.

*Division of Research, Kaiser Permanente, Oakland, CA

Department of Population Medicine, Harvard Pilgrim Health Care Institute and Harvard Medical School, Boston, MA

Jen Associates Inc., Cambridge, MA

§Department of Internal Medicine, University of Michigan, Ann Arbor, MI

Kaiser Permanente Center for Health Research, Honolulu, HI

The Heller School for Social Policy and Management, Brandeis University, Waltham, MA

Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website,

Supported by grants from the National Institute on Aging [R01AG032249] and the Agency for Health Care Research and Quality [R01 HS018577]. A.S.A., D.R.D., and S.B.S. also received support from the Health Delivery Systems Center for Diabetes Translational Research funded by the National Institute for Diabetes, Digestive and Kidney Diseases [P30DK092924]. A.S.A. is also a coinvestigator in the Learnings in Diabetes Prevention from an Integrated Delivery System [U58 DP002721] and Medication Adherence and Social Disparities in Diabetes [R01 DK080726-01] studies. C.M.T. is supported by a career development award from the Agency for Health Care Research and Quality [K01 HS018072].

The authors declare no conflict of interest.

Reprints: Alyce S. Adams, PhD, Division of Research, Kaiser Permanente, 2000 Broadway, Oakland, CA 94612. E-mail:

© 2014 by Lippincott Williams & Wilkins.