One year pre-diagnostic prevalence and associated factors of polypharmacy and potentially inappropriate medication use in community-dwelling adults with mild cognitive impairment or dementia in Norway (2014–2024): A registered report protocol

Background People with cognitive impairment frequently have multiple comorbidities, and polypharmacy is highly prevalent, affecting nearly half of individuals with mild cognitive impairment and dementia. The use of potentially inappropriate medications (PIMs), including those specifically problematic for cognitive impairment (PIMcog), increases with the total number of medications and may exacerbate cognitive symptoms or increase the risk of adverse drug events. However, the prevalence of polypharmacy and PIMcog use among patients diagnosed with MCI or dementia in Norwegian specialist outpatient clinics has not been described. Methods We will conduct a retrospective cohort study linking national health registries to estimate the prevalence of polypharmacy and PIMcog use in the year prior to diagnosis of mild cognitive impairment or dementia. Data from the Norwegian Registry of Persons Assessed for Cognitive Symptoms will be linked to dispensing data from the Norwegian Prescribed Drug Registry and comorbidity data from the Norwegian Patient Registry. The study population will include all patients diagnosed with mild cognitive impairment or dementia in Norwegian specialist outpatient clinics from 2014 to 2024. We will estimate the twelve-month prevalence of polypharmacy and PIMcog use preceding diagnosis, compare sociodemographic and clinical characteristics between PIMcog users and non-users, and identify factors associated with PIMcog use. Expected impact By describing the one-year prevalence and patterns of polypharmacy and PIMcog use and associated factors prior to mild cognitive impairment and dementia diagnosis, the findings may inform targeted deprescribing interventions and safer prescribing strategies for individuals with cognitive impairment.