Medication nonadherence and subsequent risk of hospitalisation and mortality among older adults.

ABSTRACT

BACKGROUND: Despite a higher risk for medication nonadherence among older adults residing in the community, few prospective studies have investigated the health outcomes associated with nonadherence in this population or the possible variations in risk in urban versus rural residents. OBJECTIVES: The primary objective of this study was to examine, in a prospective manner, the risk for hospitalisation (including an emergency department visit) and/or mortality associated with medication nonadherence in older, at-risk adults residing in the community. A secondary objective was to examine differences in the prevalence, determinants and consequences of medication nonadherence between rural and urban home care clients. METHODS: Data were derived from a 1-year prospective study of home care clients aged > or =65 years (n = 319) randomly selected from urban and rural settings in southern Alberta, Canada. Trained nurses conducted in-home assessments including a comprehensive medication review, self-report measures of adherence and the Minimum Data Set for Home Care (MDS-HC) tool. Hospitalisation and mortality data during 12-month follow-up were obtained via linkages with regional administrative and vital statistics databases. RESULTS: Nonadherent clients showed an increased but nonsignificant risk for an adverse health outcome (hospitalisation, emergency department visit or death) during follow-up (hazard ratio [adjusted for relevant covariates] = 1.24, 95% CI 0.93, 1.65). Subgroup analyses suggested this risk may be higher for unintentional nonadherence (unadjusted hazard ratio = 1.55, 95% CI 0.97, 2.48). The prevalence of nonadherence was similar among rural (38.2%) and urban (38.9%) clients and was associated with the presence of vision problems, a history of smoking, depressive symptoms, a high drug regimen complexity score, residence in a private home (vs assisted-living setting) and absence of assistance with medication administration. In both settings, approximately 20% of clients received one or more inappropriate medications. CONCLUSIONS: Although not associated with rural/urban residence, medication nonadherence was common in our study population, particularly among those with depressive symptoms and complex medication regimens. The absence of a significant association between overall medication nonadherence and health outcomes may reflect study limitations and/or the need to differentiate among types of nonadherent behaviours.