Patterns of statin utilisation for new users and market dynamics in South Korea: a 13-year retrospective cohort study

OBJECTIVE: This study analysed utilisation of statins for new statin users and assessed market dynamics of statins in South Korea. DESIGN: This study is a retrospective cohort study. SETTING: The yearly claims data for statins were retrieved from the National Health Insurance Service-National Sample Cohort. MAIN OUTCOME MEASURE: We are interested in new statin users during 2003–2015 in Korea. Information on prescribed statins, including intensity of statins and entry of new and follow-on statins in the market, and healthcare institutions that prescribed the statins were also collected. In time series analysis, we estimated the effect of introduction of generics in the market, specifically for newly prescribed statin users. RESULTS: This 13-year longitudinal study of a sample cohort provided by the National Health Insurance Service found that the incidence of new statin user increase from 838.1/100 000 persons in 2003 to 1626.9/100 000 persons in 2015. Most new users were initiated on a monotherapy that was prescribed at primary healthcare institutions. However, the statin market for new users were quite dynamic in Korea. First, the most commonly prescribed statin changed several times during the study period. Second, the use of moderate-intensity statins increased from 57% in 2003 to 92% in 2015. In line with this result, we could not observe substantial differences in prescription of statins in groups having selected diseases history. Lastly, we found market invasion or switch of statins among new statin users, specifically at primary healthcare institutions. CONCLUSION: Similar to other countries, the incidence of new statin users has been increased in Korea. However, the statin market in Korea is quite dynamic compared with other countries. Interestingly, discounted price of originals after the introduction of generics immediately expand markets or substitute the market particularly in primary healthcare institutions in Korea.