Pharmacist-Led Interventions for Polypharmacy Management in Older Adults: A Systematic Review of Strategies and Outcomes in the United Kingdom and the Republic of Ireland.

Polypharmacy in older adults increases risks of adverse drug reactions (ADRs), hospitalisations, and mortality. Pharmacist-led interventions using validated tools (e.g., STOPP/START, MAI, STOPPFrail) aim to optimise prescribing, yet their impact on clinical and economic outcomes in UK/Ireland health systems remains underexplored. This systematic review aimed to critically assess the impact of pharmacist-led deprescribing interventions on PIP, clinical outcomes, and costs in older adults (≥65 years) across the UK and Ireland. Following PRISMA 2020 guidelines, four databases (PubMed, Scopus, Web of Science, Cochrane Library) were searched for studies (2010-2024). Eligible studies included randomised trials, observational designs, and intervention studies in hospitals, care homes, community pharmacies, and intermediate care settings. Fourteen studies met the inclusion criteria. The risk of bias was assessed using CASP checklists. Narrative syntheses and heat maps summarised the findings. Twelve of fourteen studies reported positive outcomes: reductions in potentially inappropriate medications, ADRs, medication burdens, and falls/fall risks. Medication appropriateness improved significantly in 35% of studies using the MAI. STOPPFrail reduced PIMs in care homes, while the MAI enhanced complex hospital reviews. Community interventions improved adherence and reduced the use of fall risk drugs. No studies demonstrated a reduction in hospitalisations, mortality, or the length of stays. Economic analyses showed mixed cost-effectiveness. Key barriers included low uptake of pharmacist recommendations and short follow-up periods. Pharmacist-led interventions have significantly improved the prescribing quality and reduced medication-related risks, but they fail to impact hospitalisations or mortality due to implementation gaps. Context-specific tools and policy reforms-including expanded pharmacist roles and electronic decision support-are critical for sustainability. Future research should focus on long-term outcomes, cost-effectiveness, and multidisciplinary integration.