Trends in Hyperpolypharmacy Before and After Nursing Home Admission Among Older Adults in Ontario, Canada

•What is the primary question addressed by this study?How does the prevalence of hyperpolypharmacy (ten or more medications) and common drug classes change over time among older adults prior to nursing home admission?•What is the main finding of this study?In the ten years prior to nursing home admission, the prevalence of hyperpolypharmacy nearly increased three-fold among older adults aged 75 years and older.Following admission, the prevalence of hyperpolypharmacy increased further and then stabilized thereafter.Trends over time varied by drug classes with antidepressants (three-fold), antipsychotics (seven-fold) and cholinesterase inhibitors (14-fold) showing increasing trends prior to admission, while cardiovascular medications peaked approximately 4 to 5 years prior to admission.•What is the meaning of the finding?There might be opportunities for medication reconciliation initiatives throughout the life course (in both community settings prior to admission and subsequent nursing home settings) to ensure medication appropriateness and support deprescribing, if clinically appropriate. To examine trends in the prevalence of hyperpolypharmacy prior to and following nursing home admission in Ontario, Canada. We conducted a cohort study of adults aged 75+ years admitted to nursing homes between 2017 and 2020 using health administrative data (n = 61,470). The prevalence of hyperpolypharmacy (≥10 dispensed drugs) was assessed quarterly from ten years prior to 1.5 years following admission. Over ten years, the prevalence of hyperpolypharmacy increased from 4.4% to 12.0% (+0.2% per quarter, [p