Dosing patterns and costs of tumor necrosis factor inhibitor use for rheumatoid arthritis

Differences in dosing patterns and costs among patients with rheumatoid arthritis (RA) treated with the tumor necrosis factor (TNF) inhibitors etanercept, adalimumab, and infliximab were analyzed on the basis of claims data.

Commercial health insurance claims data from January 2004 through December 2005 from the PharMetrics Patient-centric Database were analyzed. Adults (> or =18 years of age) with RA with a minimum of two claims for the same TNF inhibitor within a 12-month period and with at least 18 months of continuous enrollment in the database (encompassing a 6-month preindex period and a 12-month follow-up period) were included. Patients were considered treatment naive if they had no claims for a TNF inhibitor during the preindex period; continuing patients had at least one TNF-inhibitor claim during the preindex period.

A total of 845 treatment-naive and 3783 continuing patients were included. Medication use, costs, and health care use were generally similar among the treatment groups in the preindex period for both naive and continuing patients. Among both naive and continuing patients, dose increases from the first to the last prescription were most likely to occur in the infliximab group (26% and 24%, respectively) compared with the adalimumab (10% and 9%) and etanercept (1% and 3%) groups. Etanercept was associated with the lowest and infliximab with the highest total anti-TNF therapy costs. Anti-TNF-related costs were higher among patients with a high index dose, a dose increase, or both during the follow-up period than among those without.

Dose increases with TNF inhibitors commonly occurred in RA patients in the clinical setting and were associated with greater costs of anti-TNF therapy.