Medication Nonadherence and Subsequent Risk of Hospitalisation and Mortality among Older Adults
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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.
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.
Data were derived from a 1-year prospective study of home care clients aged ≥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.
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.
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.
The RAI-HC (Resident Assessment Instrument for Home Care) study/initiative was supported by an unrestricted grant from The Merck Company Foundation, the philanthropic arm of Merck & Co. Inc., Whitehouse Station, NJ, USA to the Institute of Health Economics.
We are most grateful to the four home care nurses (Michelle Copeland and Sue Couchman from the Calgary Health Region and Bonnie Matson and Trudy Harbidge from the Chinook Health Region) for their data collection efforts and clinical input into the RAI-HC study. We wish to also acknowledge Chad Mitchell for his clinical input and assistance with drug coding. Special thanks is also given to the 330 home care clients and their caregivers (formal and informal) who graciously gave of their time to participate in this important study.
Shelly Vik is currently a PhD candidate, funded by the Canadian Institutes of Health Research — Skeletal Health, and Alberta Bone and Joint Training Programs. Dr Maxwell is funded by a New Investigator Award from the Canadian Institutes of Health Research — Institute on Aging and a Population Health Investigator Award from the Alberta Heritage Foundation for Medical Research (AHFMR). Dr Hogan is the holder of the Brenda Strafford Foundation Chair in Geriatric Medicine, University of Calgary. The Chair provides financial support to Drs Maxwell and Hogan. Dr Johnson holds a Government of Canada Research Chair in Diabetes Health Outcomes and an AHFMR Health Scholar Award. Dr Patten also holds an AHFMR Health Scholar Award.
Over the past 5 years, Dr Hogan has given presentations, consulted and participated in dementia studies sponsored by the following companies: Janssen-Ortho, Merck, Neurochem, Novartis and Pfizer. The other authors have no conflicts of interest that are directly relevant to the content of this study.
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