An observational study of tocilizumab and TNF-α inhibitor use in a Japanese community hospital: different remission rates, similar drug survival and safety.

Objective: To assess the effectiveness, drug survival and safety of tocilizumab compared with TNF-α inhibitors in clinical practice.

Methods: Patients in the Cohort of Arthritis Biologic Users at Kameda Institute (CABUKI) registry who were on biologics during July 2003 to October 2010 were included. Remission rates at 6 months, Kaplan-Meier drug survival estimates and serious adverse event (SAE) rates were compared.

Results: A total of 247 RA patients were analysed. For first-line biologic users, the 6-month 28-joint DAS (DAS-28)-ESR remission rates were 66.7% for tocilizumab vs 25.8% for TNF inhibitors (P < 0.001, Fisher's exact test). This advantage disappeared with the application of the newly suggested Boolean remission criterion for clinical trials: 0% for tocilizumab vs 8.2% for TNF inhibitors (P = 0.367, Fisher's exact test). Tocilizumab users in DAS-28-ESR remission had lower mean ESR (3.9  mm/h for tocilizumab vs 7.9  mm/h for TNF inhibitors, P = 0.026, t-test) and higher mean swollen joint count (2.6 for tocilizumab vs 1.3 for TNF inhibitors, P = 0.036, t-test), thus failing to meet the more stringent Boolean criteria. First- and second-line tocilizumab users showed similar drug survival and SAE rates compared with TNF inhibitor users.

Conclusion: Tocilizumab had drug survival and safety profiles similar to those of TNF inhibitors in this Japanese single-centre registry. Tocilizumab was superior to TNF inhibitors when compared at 6 months by DAS-28-ESR remission. However, the newly suggested Boolean criteria are more appropriate measures of effectiveness as DAS-28-ESR remission by tocilizumab was mainly due to very low ESR in our study population.