Direct Medical Costs Among an Inception Cohort of Patients With Inflammatory Arthritis and Osteoarthritis

Existing cost-of-illness studies on inflammatory arthritis (IA) and osteoarthritis (OA) often are cross-sectional, include patients with various disease durations, and rely primarily on claims data, which might not provide an accurate estimation of the associated costs. To address these limitations, we aimed to (1) quantify direct medical costs of an inception cohort of patients with IA and OA incurred from six months before to one year after diagnosis using hospital billing data and (2) identify cost drivers among these patients.

All costs incurred in the hospital during the six months before diagnosis (Study Period 1), the 1st to 6th month after diagnosis (Study Period 2), and the 7th to 12th month after diagnosis (Study Period 3) were extracted from hospital billing records and assessed for inclusion in the cost estimation.

A total of 85 rheumatoid arthritis (RA), 45 spondyloarthritis (SpA), 38 psoriatic arthritis (PsA), and 280 OA patients were included in this study. The highest direct medical costs were observed among patients with SpA in Study Period (1) and among patients with RA in Study Periods (2) and (3), while the lowest direct medical costs were observed among patients with OA in all three study periods. The largest cost drivers varied across study periods and among patients with different conditions.

High direct medical costs were observed among patients with IA and OA both before and after diagnosis. The varying cost drivers over time and across different arthritis could provide a foundation for future healthcare resource planning.