Address correspondence to Vicki Fung, Ph.D., Division of Research, Kaiser Permanente Medical Care Program, 2000 Broadway, 3rd floor, Oakland, CA 94612; e-mail: Vicki.Fung@kp.org. Carol M. Mangione, M.D., M.S.P.H., Norman Turk, M.S., and Elaine S. Quiter, M.S., are with the Department of Medicine, Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at UCLA, Los Angeles, CA. Jie Huang, Ph.D., Julie A. Schmittdiel, Ph.D., and John Hsu, M.D., M.B.A., M.S.C.E., are with the Division of Research, Kaiser Permanente Medical Care Program, Oakland, CA.
Falling into the Coverage Gap: Part D Drug Costs and Adherence for Medicare Advantage Prescription Drug Plan Beneficiaries with Diabetes
Version of Record online: 30 DEC 2009
© Health Research and Educational Trust
Health Services Research
Volume 45, Issue 2, pages 355–375, April 2010
How to Cite
Fung, V., Mangione, C. M., Huang, J., Turk, N., Quiter, E. S., Schmittdiel, J. A. and Hsu, J. (2010), Falling into the Coverage Gap: Part D Drug Costs and Adherence for Medicare Advantage Prescription Drug Plan Beneficiaries with Diabetes. Health Services Research, 45: 355–375. doi: 10.1111/j.1475-6773.2009.01071.x
- Issue online: 8 MAR 2010
- Version of Record online: 30 DEC 2009
- prescription drugs;
Objective. To compare drug costs and adherence among Medicare beneficiaries with the standard Part D coverage gap versus supplemental gap coverage in 2006.
Data Sources. Pharmacy data from Medicare Advantage Prescription Drug (MAPD) plans.
Study Design. Parallel analyses comparing beneficiaries aged 65+ with diabetes in an integrated MAPD with a gap versus no gap (n=28,780); and in a network-model MAPD with a gap versus generic-only coverage during the gap (n=14,984).
Principal Findings. Drug spending was 3 percent (95 percent confidence interval [CI]: 1–4 percent) and 4 percent (CI: 1–6 percent) lower among beneficiaries with a gap versus full or generic-only gap coverage, respectively. Out-of-pocket expenditures were 189 percent higher (CI: 185–193 percent) and adherence to three chronic drug classes was lower among those with a gap versus no gap (e.g., odds ratio=0.83, CI: 0.79–0.88, for oral diabetes drugs). Annual out-of-pocket spending was 14 percent higher (CI: 10–17 percent) for beneficiaries with a gap versus generic-only gap coverage, but levels of adherence were similar.
Conclusions. Among Medicare beneficiaries with diabetes, having the Part D coverage gap resulted in lower total drug costs, but higher out-of-pocket spending and worse adherence compared with having no gap. Having generic-only coverage during the gap appeared to confer limited benefits compared with having no gap coverage.