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Does Medication Adherence Following a Copayment Increase Differ by Disease Burden?
Author(s) -
Wang Virginia,
Liu ChuanFen,
Bryson Christopher L.,
Sharp Nancy D.,
Maciejewski Matthew L.
Publication year - 2011
Publication title -
health services research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 121
eISSN - 1475-6773
pISSN - 0017-9124
DOI - 10.1111/j.1475-6773.2011.01286.x
Subject(s) - copayment , comorbidity , veterans affairs , medicine , propensity score matching , pharmacy , observational study , diabetes mellitus , retrospective cohort study , emergency medicine , family medicine , health care , health insurance , endocrinology , economics , economic growth
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.