Polypharmacy and associated factors in South Korean elderly patients with dementia: An analysis using National Health Insurance claims data

Background: Dementia is accompanied by several symptoms, including cognitive function decline, as well as behavioral and psychological symptoms. Elderly patients with dementia often experience polypharmacy, the concurrent use of multiple medications, due to chronic comorbidities. However, research on polypharmacy in patients with dementia is limited. This study aimed to characterize polypharmacy and associated factors among elderly patients with dementia in South Korea, and compare the characteristics of patients with and without dementia patients. Methods: From the National Health Insurance Service (NHIS)-Senior cohort database, we extracted data on patients aged≥60 years who received outpatient treatment in 2019. Polypharmacy was defined as the concurrent use of five or more different oral medications for ≥90 days; excessive polypharmacy referred to the concurrent use of ten or more different oral medications for ≥90 days. We compared the prevalence of polypharmacy between patients with and without and identified the associated factors using a logistic regression model. Results: About 70.3% and 23.7% of patients with dementia exhibited polypharmacy and excessive polypharmacy, respectively. After adjusting for conditions such as age and Charlson’s comorbidity index, the likelihood of polypharmacy and excessive polypharmacy significantly increased over time after the diagnosis of dementia. Additionally, under the same conditions, Medical Aid beneficiaries with dementia were more likely to experience polypharmacy and excessive polypharmacy compared to patients with dementia covered by National Health Insurance (NHI). Conclusion: This study reports the latest evidence on the status and risk factors of polypharmacy in elderly patients with dementia. We proposed that careful monitoring and management are required for patients at high risk for polypharmacy.