3079 — Dual System Use and Drug Adherence among VA Patients with Hypertension

Prentice JC (Health Care Financing and Economics (HCFE); VA Boston Healthcare System), Pizer SD (HCFE and Boston University)

Objectives:
Non-adherence to hypertension medication results in poorer health outcomes and higher healthcare costs. However, research has not examined the effect of healthcare financing transitions on medication adherence. Veterans transition from the Department of Defense healthcare system to the VA healthcare system after military discharge, and disabled or poorer veterans may transition between the VA and Medicaid. The recent expansion of prescription drug benefits to Medicare enrollees will increase transitions of older VA patients as individuals find drug coverage that best fits their needs. This study is the first to examine whether veterans who switch between healthcare systems have higher medication non-adherence rates.

Methods:
The study population is veterans enrolled in both Medicaid and the VA who had a hypertension diagnosis in a six-month baseline period. All VA and Medicaid claims for beta-blockers, alpha-blockers, calcium channel blockers, diuretics, and ACE inhibitors were identified. Veterans were categorized as obtaining hypertension drugs from only the VA or Medicaid (single system users) or transitioning from one system to the other (switchers). The outcome measure over a 12-month follow-up period was non-adherence rates. This was defined as: number of days without hypertension drugs/number of days veterans needed hypertension drugs. To account for the simultaneous determination of switching between systems and health status, we ran linear regression models using instrumental variable (IV) estimation to predict non-adherence.

Results:
In ordinary least squares regression, switching systems was positively and significantly associated with more gaps in medication. The effect remains for beta-blockers, and borders on significance for calcium channel blockers and ACE inhibitors in IV regression.

Implications:
This study finds a significant and positive relationship between switching healthcare systems for prescriptions and medication non-adherence. Future research should confirm this relationship and determine why the transition causes adherence problems.

Impacts:
VA policymakers and clinicians should pay particular attention to veterans who are entering or exiting the VA system when managing medication adherence. Policies such as refilling expired prescriptions until individuals are enrolled and accessing the new health care system may need to be implemented to ensure veterans receive drugs as seamlessly as possible.