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Article
Adherence and occurrence of fractures after switching to once-monthly oral bisphophonates
Meyers Primary Care Institute Publications and Presentations
  • Becky A. Briesacher, University of Massachusetts Medical School
  • Susan E. Andrade, University of Massachusetts Medical School
  • Leslie R. Harrold, University of Massachusetts Medical School
  • Hassan Fouayzi, University of Massachusetts Medical School
  • Robert A. Yood, University of Massachusetts Medical School
UMMS Affiliation
Department of Medicine, Division of Geriatric Medicine; Meyers Primary Care Institute; Department of Medicine, Division of Rheumatology
Date
12-1-2010
Document Type
Article
Medical Subject Headings
Bone Density Conservation Agents; Databases, Factual; Diphosphonates; Drug Administration Schedule; Female; Fractures, Bone; Humans; Male; *Medication Adherence; Middle Aged; Osteoporosis
Abstract

PURPOSE: Reducing dosing demands of medications generally increases adherence, although this relationship has not been demonstrated with the once-monthly oral bisphosphonates (BP). The study aim is to test whether switching from once-weekly BPs to once-monthly BPs improves adherence and fracture risk.

METHODS: This is an interrupted times-series analysis of new users of once-weekly BPs in a nationwide administrative health database from 2003 to 2007. Participants include 1835 individuals who switched to once-monthly BPs and two propensity-matched comparator groups: 1835 individuals who switched to a different once-weekly BP, and 1835 who did not switch. We measured changes in adequate adherence pre- and post-switch as monthly medication possession ratio >0.80, and calculated incidence rate ratios (IRR) of osteoporotic fractures.

RESULTS: All study groups experienced major adherence failure in the first year of therapy: the proportion of adequate adherers was 42% among once-monthly switchers, 47% among once-weekly switchers, and 37% among nonswitchers. However, the once-monthly switch was associated with less adherence failure (4% fewer adherers per month pre-switch vs. 1% fewer adherers per month post-switch, p<0.000). There was no statistically significant change in adherence rates for the other groups. We did not detect significantly reduced fracture risk with once-monthly switch: 1 year post-switch, the fracture incidence risk ratios for once-monthly switchers relative to once-weekly switchers were IRR 0.83, 95% CI: 0.50-1.36, and IRR 0.90, 95% CI: 0.54-1.49, relative to nonswitchers).

CONCLUSIONS: Reducing the dosing demands of oral bisphosphonates from once-weekly to once-monthly decreased adherence failure but had an uncertain impact on fracture risk.

Rights and Permissions
Citation: Pharmacoepidemiol Drug Saf. 2010 Dec;19(12):1233-40. doi: 10.1002/pds.2048. Epub 2010 Oct 28. Link to article on publisher's site
Related Resources
Link to Article in PubMed
PubMed ID
21108489
Citation Information
Becky A. Briesacher, Susan E. Andrade, Leslie R. Harrold, Hassan Fouayzi, et al.. "Adherence and occurrence of fractures after switching to once-monthly oral bisphophonates" Vol. 19 Iss. 12 (2010) ISSN: 1053-8569 (Linking)
Available at: http://works.bepress.com/becky_briesacher/30/