COMPARATIVE MEDICATION ADHERENCE RATES ACROSS THE DIFFERENT CLASSES OF RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM (RAS) ANTIHYPERTENSIVE DRUGS IN PATIENTS WITH HYPERTENSION

Sunday, October 20, 2013
Key Ballroom Foyer (Hilton Baltimore)
Poster Board # P1-37
Health Services, and Policy Research (HSP)

Sandhya Mehta, PhD, John Scoggins, PhD, Barton Jones, MS, Christie Teigland, PhD, Alexis Parente, MA, Zulkarnain Pulungan, PhD, Ping Chen, MD, Xiaoqin Yang, PhD, Bin Zhang, MS and Reshma Bhattacharjee, MPH, Inovalon, Bowie, MD
Purpose: Hypertension is a common and highly treatable condition which can lead to other major cardiovascular, cerebrovascular and renal diseases.  Renin-angiotensin-system (RAS) agents; that include angiotensin-converting enzyme (ACEs) inhibitors, angiotensin-receptor blockers (ARBs) and direct renin inhibitors (DRIs), are among the most effective antihypertensive pharmacotherapies.  The purpose of this study is to address a high priority need for observational studies examining differences in longitudinal adherence across the different RAS inhibitor classes identified in the 2011 Agency for Healthcare Research and Quality (AHRQ) comparative effectiveness review.

Method:

This retrospective cohort study was conducted using a large nationally representative administrative claims database. To make the three groups comparable, patients were included in the cohort if they were (1) > 18 years of age; (2) new users of RAS drugs (i.e. no prescriptions for any RAS in the 12-months prior to treatment); (3) continuously enrolled for twelve months before and after drug initiation; and (4) diagnosed with hypertension on or before initiating treatment.  Patients were excluded if they (1) had a prescription for fixed-dose antihypertensive combination drugs; (2) switched or added a different RAS category; or (3) were hospitalized for any reason during the observation period. The primary outcome was the proportion of patients achieving optimal adherence (≥ 80%) after one year. A multivariate logistic regression model was used after controlling for demographic, clinical and health services utilization factors.

Result: A total of 167,376 patients met the inclusion criteria: ACEs 137,348 (82%); ARBs 29,543 (17.6%); DRIs 485 (0.29%).  Adherence rates were similar in patients receiving ARBs (57%) and ACEs (56%), and lower in those treated with DRIs (51%).  After controlling for confounders, patients taking DRIs had significantly higher risk of non-adherence than those taking ACEs (odds ratio 0.82, 95% CI 0.68-0.98). No difference in adherence rates was found between ACEs and ARBs.  

Conclusion:

This study addresses an important evidence gap and provides new information about relative adherence across different RAS medications. Patients taking DRIs were found to have significantly lower adherence, which can result in poor patient outcomes and higher costs.  Adherence to RAS drugs is also an important health plan quality measure, and this information can help guide optimal treatment protocols and improve quality ratings.