Medication Adherence Outcomes in Elderly Patients with Hypertension and Chronic Kidney Disease: a Geographical Approach

Abstract

OBJECTIVES Chronic kidney disease (CKD) patients with uncontrolled blood pressure are at high risk of cardiovascular events, hospitalization, and mortality. There is limited research evaluating utilization patterns of anti-hypertensives in hypertensive CKD patients. This study aims to assess anti-hypertensives use, particularly, angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin-receptor blockers (ARBs) in the United States, and explore contextual and individual risk factors of treatment compliance. METHODS Hypertensive CKD patients were selected using Medicare 5% sample claims data from the United States Renal Data System (USRDS) databases (2006-2013). We included patients who diagnosed with hypertension and CKD, and followed them from Jan 1, 2008 to Dec 31, 2013. We first investigated medication treatment patterns among incident CKD patients. We then performed time-dependent survival analyses to evaluate long-term benefits of being adherence to ACEIs/ARBs. Medication adherence in this study was measured by proportion days covered (PDC). Lastly, we used geographically weighted regression model (GWR) to explore risk factors of medication adherence. RESULTS Approximately 50% of incident hypertensive CKD patients received guideline-recommended ACEIs/ARBs after their first diagnosis of CKD. Anti-hypertensive regimens including ACEIs/ARBs and statins yielded better CKD outcomes than regimens without these drugs. Additionally, continuously being adherent to ACEIs and ARBs was associated a significant decline in risk of end-stage renal disease (ESRD) and mortality in long run. However, only 61% of hypertensive CKD who used ACEIs/ARBs had good medication compliance (PDC ≥80%). Patients residing in the Northeast region and the Midwest region demonstrated better adherence than those residing in the Southern United States. Availability of primary resources, neighborhood deprivation status, and coverage of Part D Low-income Subsidy (LIS) were factors related with medication adherence. Geographically varied association between contextual characteristics and adherence were displayed by maps. CONCLUSIONS Utilization of guideline-recommended ACEIs/ARBs is suboptimal in elderly patients with hypertension and CKD in the United States, although they had significant long-term benefits on CKD outcomes. Adherence to ACEIs/ARBs is geographically differentiated across the United States. Contextual and individuals risk factors identified in this study are helpful to design population-based strategies in a local area to promote medication compliance, from a population perspective.