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

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. 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. 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. 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.