Sakai R, et al. - In this retrospective and the descriptive population-based study performed using claims data provided by Health Insurance Review and Assessment in Korea and JMDC Inc in Japan, experts contrasted medication prescriptions for persons with knee OA (KOA) in the real world in Korea (N = 1,133,138) and Japan (N = 10,498). The prevalence of NSAID usage in Japan was significantly higher compared with that in Korea. In Korea vs Japan, analgesics like acetaminophen and symptomatic slow-acting drugs for OA (SYSADOA) were significantly more often used. Compared with Korean people, Intra-articular injection (IAI) of corticosteroids or hyaluronic acid was administered more often in Japanese. Hence, medication patterns for KOA in Korea and Japan were defined for the first time. Moreover, in Japan, the usages of NSAIDs and IAI were more prevalent, whilst other pain killers and SYSADOA were more usually prescribed in Korea.