The prevalence and impact of medication-related harm in people living with dementia − a systematic review and meta-analysis

Objective People living with dementia (PLWD) take more medications than those without dementia, increasing their risk of medication-related harm, defined as any negative outcome related to medication use, encompassing both harm events and outcomes. This systematic review aimed to determine the prevalence of medication-related harm in PLWD and evaluate its impact across a range of outcomes. Methods Twelve databases were searched from inception to April 2025. Studies of any design reporting the prevalence and/or outcomes of medication-related harm in PLWD were included. Study quality was assessed using appropriate risk of bias tools. A meta-analysis was conducted to determine combined hazard ratios (HRs) and 95% confidence intervals (CIs). Results In total, 115 studies were included (110 observational, five randomised controlled trials). Most studies (n=73) were at low risk of bias. Adverse drug events were the most commonly reported harm event (n=92), with prevalence ranging from 2.5-93.0%. Adverse health outcomes were measured in 55 studies, with 32 reporting increased risk associated with medication use. Psychoactive medications were frequently implicated (n=59 studies), with 43 reporting a link with negative outcomes. Six studies (n=25,715 participants) were included in an exploratory meta-analysis, which suggested an association between antipsychotic use and increased mortality (HR=1.42; 95% CI=1.10-1.84; p=0.008). Conclusions This review provides a comprehensive synthesis of medication-related harm in PLWD, highlighting its breadth and complexity across care settings and medication classes. The findings support the need for improved medicines optimisation strategies, including medication review and deprescribing approaches, to reduce harm in this vulnerable population.