Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2013 Jan;22(1):55-63.
doi: 10.1002/pds.3361. Epub 2012 Nov 8.

Generic alendronate use among Medicare beneficiaries: are Part D data complete?

Huifeng Yun  1 , Jeffrey R Curtis, Kenneth Saag, Meredith Kilgore, Paul Muntner, Wilson Smith, Robert Matthews, Nicole Wright, Michael A Morrisey, Elizabeth Delzell
Affiliations

Generic alendronate use among Medicare beneficiaries: are Part D data complete?

Huifeng Yun et al. Pharmacoepidemiol Drug Saf. 2013 Jan.

Abstract

Background: Generic alendronate was approved in the United States on February 6, 2008. Medicare beneficiaries might pay for generic alendronate out-of-pocket without having claims submitted, resulting in misclassification of generic alendronate use in Medicare data.

Objectives: To estimate the completeness of generic alendronate use in 2008 Medicare Part D data; to identify factors associated with staying on branded alendronate versus switching to a generic product.

Methods: We identified Medicare beneficiaries highly adherent (medication possession ratio ≥80%) with branded alendronate during 1/1/06-2/6/07 ("2007 cohort") and during 1/1/07-2/6/08 ("2008 cohort"). The outcome was medication status at the end of follow-up (12/31/2007 or 12/31/2008), classified as continued branded alendronate, switched to generic alendronate, switched to another bisphosphonate or presumed discontinued bisphosphonate therapy. Cox regression estimated the hazard ratio (HR) for discontinuation in 2008 compared to 2007. Multinomial logistic regression identified factors associated with medication status for the 2008 cohort.

Results: Among 15,310 subjects using branded alendronate in the 2008 cohort, 81% switched to generic alendronate. The proportion presumably discontinuing bisphosphonate therapy was 8.9% in 2008 compared to 7.7% in the 2007 cohort (adjusted HR, 1.15; 95% confidence interval, 1.05, 1.26). Factors associated with staying on branded alendronate in 2008 were higher income, eligibility for a low income subsidy and use of Fosamax® plus vitamin D.

Conclusion: Evaluation of Medicare prescription drug data suggests that the amount of missing claims for generic alendronate in 2008 was not substantial, and misclassification of exposure in studies examining alendronate use post-generic product availability should be minimal.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Cohort diagram
Figure 2
Figure 2
Time Trends in Switching and Apparent Discontinuation among Alendronate Users in 2007-2009
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. U.S. Department of Health & Human Services. U.S. Food and Drug Administration [Jan 31, 2012];FDA approved Drug Products. Available at http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?fuseacti....
    1. Medco Health Solutions I. 2009 Drug trend report. The great Healthcare debates. Prescriptions for meaningful reform. 2009:11.
    1. Cooper C, Atkinson EJ, Jacobsen SJ, O'Fallon WM, Melton LJ., III Population-based survival after osteoporotic fractures. Am J Epidemiol. 1993;137(9):1001–1005. - PubMed
    1. Sikka R, Xia F, Aubert R. Estimating medication persistency using administrative claims data. Am J Manag Care. 2005;11(7):449–457. - PubMed
    1. Centers for Medicare & Medicaid Services [Sept 17th, 2012];Medicare & Medicaid Statistical Supplement. Available at http://www.cms.gov/Research-Statistics-Data-and-Systems/Statistics-Trend....

Publication types

MeSH terms