Prescription drug insurance and cost-related medication nonadherence among Medicare seniors: findings from two national surveys

Abstract

Objectives Numerous studies suggest that cost-related nonadherence (CRN) to prescribed medications can have potentially devastating consequences, particularly for seniors with chronic illnesses, such as cardiovascular disease or diabetes. In this study, we examined if and how having drug insurance was associated with the occurrence of CRN among older adults, and assessed the role of chronic health conditions in moderating this relationship. Methods Using two independent and nationally representative data sources, the ongoing Medical Expenditure Panel Survey (MEPS) and the Health and Retirement Study (HRS), we estimated the prevalence of CRN among Medicare seniors who reported regularly taking prescribed medication. We then ran multivariable regression models to quantify the relationship between drug insurance and the occurrence of CRN. The potential endogeneity of drug insurance was carefully investigated. Key findings We observed CRN among 2.4% of seniors over the past 12 months (based on MEPS data), and 7.0% of seniors over the past 24 months (based on HRS data). Among seniors with multiple chronic conditions, having insurance was associated with a lower likelihood of CRN, both over the past 12 months (OR = 0.483, 95% CI, 0.281 to 0.830), and over the past 24 months (OR = 0.321, 95% CI, 0.258 to 0.398). Among seniors with one or no chronic conditions this relationship was weaker, both over the past 12 months (OR = 0.667, 95% CI, 0.299 to 1.489), and over the past 24 months (OR = 0.346, 95% CI, 0.247 to 0.486). Conclusions Drug insurance was associated with a lower rate of CRN, particularly among seniors with multiple chronic conditions.