PMS11 A RETROSPECTIVE COHORT ANALYSIS OF THE BURDEN OF TOTAL KNEE ARTHROPLASTY IN JAPAN

Abstract

The number of total knee arthroplasty (TKA) procedures in Japan is expected to increase with the aging of the population given that approximately 77% of TKA patients in Japan are aged 70 or older. However, despite the availability of some registry and national-level summary statistics, relatively little national-level information is available on the treatment and cost of care for TKA patients in Japan. This study provides national-level information concerning length of stay (LOS), the cost of inpatient care, and initial diagnoses for TKA patients in Japan. A retrospective cohort analysis was conducted using data from the Medi-Scope nationwide insurance claims database between 2014 and 2019. LOS, the cost of inpatient care, and initial diagnoses were examined for 1100 TKA patients aged 18 or older. Mean LOS was 31.7 days for the period examined. The average cost of inpatient care per patient was JPY 3,236,196. Very little variation was observed for LOS and cost of inpatient care based on demographics such as age, gender, and region. The most common initial diagnoses were osteoarthritis of the knee, rheumatoid arthritis, and osteoporosis. Rheumatoid arthritis, which is associated with lower functional improvement overall for TKA patients, was indicated as an initial diagnosis for about 15% of cases. Osteoporosis, which is said to be associated with more cases of post-TKA misalignment, was indicated as an initial diagnosis for about 13% of cases. At least 15% of TKA patients suffered from an underlying condition such as rheumatoid arthritis or osteoporosis which has been associated with worse treatments outcomes. This may suggest the need for greater focus on certain patient subpopulations in treatment planning. Further sub-analyses based on care setting and type of care may also help identify subpopulations with greater unmet needs among TKA patients.