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2023 HSR&D/QUERI National Conference Abstract

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1044 — Impact of VA Medication Copayment Restructuring on Medication Adherence and Outcomes for Veterans with Hypertension

Lead/Presenter: Bridget Smith,  COIN - Hines
All Authors: Smith BM ((Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL)), Etingen B (Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL) Hogan TP (Center for Healthcare Organization and Implementation Research (CHOIR), Bedford and Boston, MA) Gonzalez B (Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL) Evans CT (Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL) Suda KJ (Center for Health Equity Research & Promotion (CHERP), Pittsburgh and Philadelphia, PA) Huo Z (Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL) Ippolito D (Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL) Burk M (VA Pharmacy Benefits Management) Cunningham F (VA Pharmacy Benefits Management), Stroupe KT (Center of Innovation for Complex Chronic Healthcare (CINCCH), Hines, IL)

Objectives:
Hypertension is a highly prevalent condition among Veterans, many of whom manage the condition with medication. In 2017, VA implemented a new 3-tiered copayment system. The copayment for Tier 1 medications decreased from $8 or $9 to $5 for a 30-day supply among Veterans who are subject to copayments. Tier 1 includes many medications that are used to treat chronic conditions, including several medications to treat hypertension. The objective of this study was to examine the impact of the copayment change on medication adherence and hypertension management for three of the most frequently prescribed hypertension medications: hydrochlorothiazide, lisinopril, and losartan.

Methods:
Using a 10% sample of male Veterans and a 100% sample of female Veterans, we identified Veterans who had received a diagnosis of hypertension before February 2016 and were prescribed one of three medications of interest 12 months before February 2017. We used a difference-in-differences approach to compare changes in medication possession ratios (MPR) and mean systolic and diastolic blood pressures levels (SBP and DBP) 12 months before and 12 months after the copayment change between Veterans who did and did not pay medication copayments. Separate multiple regression models were estimated for each medication; these models adjusted for demographic characteristics, comorbidities, and the correlation of observations between time periods.

Results:
The analyses included a total of 290,947 Veterans. Veterans in the sample were 65 years old, on average; 19% were African-American and 78% were white. Most Veterans (52%) used lisinopril; 35% used hydrochlorothiazide, and 26% used losartan. After adjusting for Veteran characteristics, the change in MPR over time was similar for Veterans who experienced the copayment decrease and Veterans who were exempt from copayments, suggesting that the copayment decrease did not impact adherence. There were no significant differences between the changes in DBP over time for the Veterans who paid and did not pay copayments. For Veterans using lisinopril, there was a significant interaction between time and copayment status (? = -.20,p = 0.041); there was a larger decrease in SBP over time for Veterans who paid copayments (137.5 to 137.0) compared to those who did not (136.1 to 135.9), suggesting that the copayment decrease was associated with a small clinical impact for Veterans using lisinopril. There were no significant differences in change over time in SBP between the copayment and no-copayment groups for Veterans using losartan or hydrochlorothiazide.

Implications:
For Veterans using lisinopril, the copayment change did result in a significantly larger improvement in SBP for Veterans who paid copayments compared to those who did not, suggesting that the decrease in price might have impacted clinical outcomes. However, our medication adherence measure did not appear to be affected by the copayment change and we did not see significant impacts in hypertension management for Veterans using losartan and hydrochlorothiazide.

Impacts:
Managing hypertension is a priority for VA to prevent morbidity and mortality. Because many Veterans struggle to pay for medications, additional research is needed to understand how to leverage copayment amounts and other strategies to increase medication adherence and improve hypertension management.