Prescribed drugs and polypharmacy in healthcare service users in South Korea: An analysis based on National Health Insurance Claims data

Objective: This study was conducted to analyze and compare the exposure to individually prescribed drugs and the prevalence of polypharmacy according to age group and concomitant disease in South Korea. Methods: The use of prescribed drugs was evaluated according to average numbers of prescription drugs used daily during a year or month, using the Korean Health Insurance Claims Database, which is representative of over 90% of citizens, in 2010 and 2011. The use of prescribed drugs was also analyzed according to concomitant diseases and age. Polypharmacy was defined as the use of 5 or more drugs daily during a specific observation period, and proportions of polypharmacy users were calculated according to comorbidity and age group. Results: The annual average numbers of daily used prescription drugs in 2010 and 2011 were 0.3 (SD = 0.5), 0.4 (SD = 0.7), 1.2 (SD = 1.5), and 2.3 (SD = 2.0) for people aged < 20 years, 20 - 49 years, 50 - 64 years, and ≥ 65 years, respectively. Proportions of individuals demonstrating polypharmacy increased with age and were 9.5% and 44.1% for elderly individuals in the year- and month-based analyses, respectively. The annual average number of daily medications used increased by ∼ 2 drugs in the concomitant disease group, and the higher mortality group used a higher number of prescribed drugs than the lower mortality group. Conclusions: The results highlight the elevated burden of multi-medication in elderly patients, and the study found that prescribed drug use increased with age and the number of concomitant diseases.