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

Virginia Wang1, Chuan-Fen Liu, Christopher L Bryson

  • 1Division of General Internal Medicine, Department of Medicine, Duke University, Durham, NC, USA. virginia.wang@duke.edu

Health Services Research
|June 22, 2011
PubMed

Insights

Medication copayment increases affect patients differently based on their health status. Lower comorbidity patients showed reduced adherence, while higher comorbidity patients maintained it, potentially increasing their out-of-pocket costs.

Area of Science:

  • Health economics
  • Pharmaceutical policy
  • Patient adherence

Background:

  • Medication copayments are a common cost-sharing mechanism.
  • Understanding the impact of copayments on medication adherence is crucial for patient health outcomes.
  • Patient comorbidity burden may influence response to copayment changes.

Purpose of the Study:

  • To compare changes in medication adherence.
  • To assess the impact of copayment increases on patients with high versus low comorbidity burden.

Main Methods:

  • Retrospective observational study at four Veterans Affairs (VA) medical centers.
  • Compared copayment-paying veterans with hypertension or diabetes to propensity score-matched exempt veterans.
  • Stratified cohorts by Diagnostic Cost Group risk score (low <1, high >1) and assessed adherence using VA pharmacy claims data (ReComp algorithm).

Main Results:

  • Veterans with lower comorbidity were more sensitive to a U.S.$5 copayment increase.
  • In lower comorbidity groups, diabetes patients had a greater adherence reduction than hypertension patients.
  • Higher comorbidity veterans, whether copayment-exempt or not, showed similar adherence trends.

Conclusions:

  • Medication copayment increases have varied effects on low- and high-risk patients.
  • High-risk patients face higher out-of-pocket costs for continued adherence.
  • Low-risk patients may increase their risk of adverse health events due to nonadherence.
Abstract

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