Trends of the prevalence of polypharmacy and potentially inappropriate medications in people with dementia from 2006 to 2021 in Hong Kong

Background Long-term prescription patterns of polypharmacy and potentially inappropriate medication (PIMs) in dementia patients were limited in the Chinese population. Objective Examine the prevalence trends of polypharmacy and PIMs in people living with dementia. Methods Using electronic healthcare data from Hong Kong(2006–2021), we evaluated trends of polypharmacy (≥5 medications) and hyperpolypharmacy (≥10 medications) prescribed within 60 days per year in dementia patients aged ≥65 years old. PIMs were identified using the 2019 Beers criteria and the Screening Tool of Older Person's Prescription version 2, with at least one prescription per year. The COVID-19 pandemic period was defined as 2020–2021. The prevalence of polypharmacy, hyperpolypharmacy, and PIMs was calculated as the affected people divided by the total number of dementia patients alive each year. Joinpoint regression models was used to analyze trends and estimate average annual percent change (AAPC). Results The prevalence of polypharmacy increased from 2006 (36.4%) to 2021 (66.4%) (AAPC: 4.0). Hyperpolypharmacy also increased from 3.3% to 21.0% (AAPC:12.7). During pandemic, stable trends were observed in polypharmacy (p = 0.08) and hyperpolypharmacy (p = 0.20). The prevalence trend of PIMs from 2006 to 2021 was stable (35.8%–35.2%, p = 0.17), with a slight increase observed after 2015 (33.5%–35.2%, p < 0.0001). Between 2006 and 2013, and after the release of the new guideline (2019–2021), the prescription rates of antipsychotics and anticholinergics decreased (both p < 0.001), while prescriptions for non-benzodiazepine (AAPC: 4.4) and benzodiazepine (AAPC: 3.6) increased. Conclusions Reviewing polypharmacy and hyperpolypharmacy among people living with dementia is needed to ensure the appropriate use of medications.