Does medication adherence following a copayment increase differ by disease burden?

Journal Article (Journal Article)

OBJECTIVES: To compare changes in medication adherence between patients with high- or low-comorbidity burden after a copayment increase. METHODS: We conducted a retrospective observational study at four Veterans Affairs (VA) medical centers by comparing veterans with hypertension or diabetes required to pay copayments with propensity score-matched veterans exempt from copayments. Disease cohorts were stratified by Diagnostic Cost Group risk score: low- (<1) and high-comorbidity (>1) burden. Medication adherence from February 2001 to December 2003, constructed from VA pharmacy claims data based on the ReComp algorithm, were assessed using generalized estimating equations. RESULTS: Veterans with lower comorbidity were more responsive to a U.S.$5 copayment increase than higher comorbidity veterans. In the lower comorbidity groups, veterans with diabetes had a greater reduction in adherence than veterans with hypertension. Adherence trends were similar for copayment-exempt and nonexempt veterans with higher comorbidity. CONCLUSION: Medication copayment increases are associated with different impacts for low- and high-risk patients. High-risk patients incur greater out-of-pocket costs from continued adherence, while low-risk patients put themselves at increased risk for adverse health events due to greater nonadherence.

Full Text

Duke Authors

Cited Authors

  • Wang, V; Liu, C-F; Bryson, CL; Sharp, ND; Maciejewski, ML

Published Date

  • December 2011

Published In

Volume / Issue

  • 46 / 6pt1

Start / End Page

  • 1963 - 1985

PubMed ID

  • 21689097

Pubmed Central ID

  • PMC3393028

Electronic International Standard Serial Number (EISSN)

  • 1475-6773

Digital Object Identifier (DOI)

  • 10.1111/j.1475-6773.2011.01286.x


  • eng

Conference Location

  • United States