Health Care Financing Transitions and Non-Adherence to Medication Among VA Patients with Hypertension

Prentice JP, Pizer SDP, Antoun HA. Health Care Financing Transitions and Non-Adherence to Medication Among VA Patients with Hypertension. Paper presented at: AcademyHealth Annual Research Meeting; 2008 Jun 9; Washington, DC.

Research Objective: Non-adherence to hypertension medication results in poorer health outcomes and higher health care costs. Cost of medication, complexity of therapy regime and the asymptomatic nature of hypertension have been identified as factors that affect adherence to medication. However, research has not examined the effect of health care financing transitions on medication adherence. Veterans frequently experience transitions into and out of the VA care system. For example, veterans transition from the Department of Defense healthcare system to the Department of Veteran Affairs (VA) after military discharge, and disabled or poorer veterans may experience transitions between the VA and Medicaid. Expansion of prescription drug benefits to Medicare enrollees in the Medicare Modernization Act of 2003 will likely further increase transitions of older VA patients as individuals seek out drug coverage that fits their needs best. This study is the first to examine whether veterans who switch between health care systems have higher non-adherence to medication rates. Study Design: This was a retrospective observational study. We extracted prescription drug utilization records for antihypertensive medication from 1999 and 2000 VA and Medicaid prescription drug claims. The dependent variable was the number of days without medication divided by the number of treatment days over a one year period. The main explanatory variable of interest was whether an individual switched between the VA and Medicaid. Ordinary least squares regression examined the effect of switching systems on gaps in medication controlling for health status and demographics. Instrumental variable (IV) regression models accounted for the potentially simultaneous determination of switching health care systems and medication adherence. For example, an acute episode may disrupt an individual's medication regime while at the same time the individual may be changing health care systems in response to this episode. Population Studied: VA enrollees who were eligible for Medicaid enrollment in 1999 or 2000 and had at least one diagnosis of hypertension during a baseline period. Principal Findings: In ordinary least squares regression, switching systems was positively and significantly associated with more gaps in medication. The effect remains for beta-blockers, calcium channel blockers and angiotensin converting enzyme inhibitors when using IV regression. Conclusions: Research has not examined if health care financing transitions affect medication non-adherence. This study provides initial evidence that there is a significant and positive relationship between the two. Future research should confirm this relationship and determine which aspects of the transition (e.g. enrollment delays) cause adherence problems. Impact Statements: Transitioning between health care financing systems may increase non-adherence to medication. VA policymakers and clinicians should pay particular attention to veterans who are entering or exiting the VA system from other health care systems, such as Medicare, Medicaid or the Department of Defense healthcare systems, 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.