Julia Prentice* Health Care Financing and Economics, VA Boston Healthcare System Steve Pizer

1. Health Care Financing Transitions & Non-Adherence to Medication Among VA Patients with Hypertension Julia Prentice* Health Care Financing and Economics, VA Boston Healthcare System Steve Pizer Health Care Financing and Economics, VA Boston Healthcare System and Boston University School of Public Health Antoun Houranieh Pharmaceutical Services VA Boston Healthcare System *This study was funded by the Department of Veterans Affairs Health Services Research and Development Service (ECI 03-199-2).

2. Hypertension is not Well Controlled • Adherence to medication - Asymptomatic nature of hypertension - Therapy regime - Out of pocket costs • Gaps or changes in drug coverage - One-quarter to one-third of MCBS beneficiaries have changes in drug coverage • Transition may cause non-adherence (e.g. gaps) - Enrollment delays - Different formularies, cost-sharing policies (e.g. copays)

3. Research Objective • Examine the association between changes in drug coverage and gaps in hypertension medication among veterans - Switch between VA and Medicaid • Hypothesis: Veterans who switch have a higher risk of experiencing gaps in medication

4. Veterans May Choose VA or Medicaid • VA - Low out-of-pocket costs - Closed network; distance - Long waits • Medicaid - Local provider - Eligibility requirements/benefits vary • Changes in health may influence program choice

5. Study Population • VA and Medicaid dual enrollees -Hypertension diagnosis -Prescription claims for hypertension drugs - Alpha-blockers - Beta-blockers - Calcium-channel blockers - Diuretics - Angiotensin converting enzyme (ACE) inhibitors • Minimized likelihood of drug coverage from other sources

6. Medication Gap Definition • Continuous Multiple-Interval Measure of Medication Gaps (CMG) CMG= # of days without drugs total number of treatment days • Percentage of days without medication - 0 to 1 - 0= individual always has needed medication - 1= individual never has needed medication

7. Financing Transition Definition X=VA prescription O=Medicaid prescription

8. Switching Once Has Higher Non-Adherence

9. Analyses • Switching predicting medication gaps - Switched once versus using one program or both programs • Risk adjusted models • Demographics (e.g. age, gender) - 28 health conditions (e.g. alcohol abuse, diabetes)

10. OLS Results

11. Switching Significantly Predicts Gaps p<0.05 p<0.05

12. Instrumental Variables Regression • Joint determination of switching and medication gaps - Health shock could cause both simultaneously • Two-stage Instrumental Variables Regression - First stage predicts switching - Uses accessibility (e.g. VA distance) and eligibility factors (e.g. Medicaid restrictiveness) - Second stage includes the predicted probability of switching

13. IV Model

14. IV Results p<0.05 OLS Results p<0.05 p<0.05

15. Conclusions and Implications • IV required to control for joint determination • Switching drug coverage increases risk of medication gaps for some drug classes - Beta-blockers, Calcium channel blockers, ACE inhibitors - Switching does not influence alpha-blockers or diuretics • Veterans entering or exiting VA system at higher risk for non-adherence - Medicare Part D - Department of Defense

16. Conclusions and Implications • Confirm importance of drug cost control policies - Transition problematic due to enrollment delays or drug cost control policies - Same relationship for all classes expected if enrollment delays - No relationship seen for cheap (diuretics) or rarely used (alpha-blockers) drugs - Different drug cost control policies (e.g. formulary restrictions, copays) may lead to gaps in other classes

17. Contact Information • Julia Prentice -Julia.Prentice@va.gov • Steve Pizer -Steven.Pizer@va.gov • Antoun Houranieh -Antoun.Houranieh@va.gov