The Polypharmacy status and factor analysis of the elderly of medical aid: A Nationwide Cohort study using Health Insurance Claims data

Objective: In order to identify the status and factors of polypharmacy of elderly of medical aid, this study compared them with national health insurance.Methods: We established a cohort for the elderly using the Health insurance claim data of 2018. Polypharmacy is defined as the use of at least five concurrent medications for over 90 days annually. We compared the risk of polypharmacy by medical aid with that of national health insurance. To analyze the status of polypharmacy of medical aid and associated factors, and compare them with those of national health insurance, we conducted Chi-square test, t-test, and multivaiate logistic regression.Result: 46.4% of national health insurance and 67.8% of medical aid showed polypharmacy. After adjusting gender, age, comorbidity, Elixhauser Comorbidity Index (ECI) scores, and the number of outpatient visits, the odds ratio (OR) of polypharmacy was 1.80 (95% Confidence interval (CI), 1.79-1.82) times higher among medical aid. The number of prescriptions, the number of total prescribed medications a year, the number of daily average prescribed medications, and the cost of annual total prescribed medications are higher among medical aid. Major factors associated with polypharmacy were diabetes, cardio-cerebrovascular diseases, ECI of 2 points or higher, and at least 16 outpatient visits a year. The OR of medical aid aged 70~74 to those aged 65~69 was 0.88 (95%CI 0.86-0.90).Conclusion: To reduce the incidence of polypharmacy among elderly, a focus needs to be placed on patients with diabetes, cardio-cerebrovascular diseases and patients who visited outpatient at least 16 times a year. The medical aid need to be manage polypharmacy, regardless of severity and age. Efforts at the national level are needed to reduce the polypharmacy of the elderly of medical aid.