Prevalence of patients with rheumatoid arthritis and age-stratified trends in clinical characteristics and treatment, based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan.

Abstract

To estimate the prevalence and age-stratified treatment trends and clinical characteristics of rheumatoid arthritis (RA) in Japan. Using 7 RA definitions, the prevalence of RA in those aged ≥16years was estimated using the National Database of Health Insurance Claims and Specific Health Checkups of Japan in the fiscal year 2017. We analyzed age-stratified trends in characteristics and treatments. Of 1116122 patients aged ≥16years with at least 1 RA-related International Classification of Diseases-10 code, 825.7 thousand patients (women, 76.3%) were assessed as having RA with an estimated prevalence of 0.65%. The highest age-stratified prevalence was 1.63% in patients aged 70-79years. Overall, 60.8% and 7.0% of patients with RA were aged ≥65years and ≥85years, respectively. Methotrexate use was most frequent in patients aged 50-59years (73.0%) and least frequent in patients aged ≥85years (38.2%). Biologic disease-modifying antirheumatic drugs use was 50.9% in patients aged 16-19years and decreased to 13.7% in those aged ≥85years. Preference for the use of tumor necrosis factor inhibitors versus abatacept decreased from 24.0:1 to 1.7:1 in patients aged 16-19years and ≥85years, respectively. The prevalence of cardiovascular disease was 3.5% in patients aged 60-69years and 12.1% in those aged ≥85years. Overall RA-related orthopedic surgeries were most prevalent in patients aged 70-79years. The estimated prevalence of patients with RA in Japan was 0.65%. Age-stratified treatment trends and clinical characteristics have been described in a super-aged society for the first time.