Are antidementia drugs associated with reduced mortality after a hospital emergency admission in the population with dementia aged 65 years and older?

Abstract

Introduction: People with dementia experience poor outcomes after hospital admission, with mortality being particularly high. There is no cure for dementia; antidementia medications have been shown to improve cognition and function, but their effect on mortality in real-world settings is little known. This study examines associations between treatment with antidementia medication and mortality in older people with dementia after an emergency admission. Methods: The design is a retrospective cohort study of people aged 65 years, with a diagnosis of dementia and an emergency hospital admission between 01/01/2010 and 31/12/2016. Two classes of antidementia medication were considered: the acetylcholinesterase inhibitors and memantine. Mortality was examined using a Cox proportional hazards model with time-varying covariates for the prescribing of antidementia medication before or on admission and during one-year follow-up, adjusted for demographics, comorbidity, and community prescribing including anticholinergic burden. Propensity score analysis was examined for treatment selection bias. Results: There were 9142 patients with known dementia included in this study, of which 45.0% (n 5 4110) received an antidementia medication before or on admission; 31.3% (n 5 2864) were prescribed one of the acetylcholinesterase inhibitors, 8.7% (n 5 798) memantine, and 4.9% (n 5 448) both. 32.9% (n 5 1352) of these patients died in the year after admission, compared to 42.7% (n 5 2148) of those with no antidementia medication on admission. The Cox model showed a significant reduction in mortality in patients treated with acetylcholinesterase inhibitors (hazard ratio [HR] 5 0.78, 95% CI 0.72-0.85) or memantine (HR 5 0.75, 95% CI 0.66-0.86) or both (HR 5 0.76, 95% CI 0.68-0.94). Sensitivity analysis by propensity score matching confirmed the associations between antidementia prescribing and reduced mortality. Discussion: Treatment with antidementia medication is associated with a reduction in risk of death in the year after an emergency hospital admission. Further research is required to determine if there is a causal relationship between treatment and mortality, and whether "symptomatic" therapy for demen-tia does have a disease-modifying effect.