Background The introduction of tocilizumab (TCZ) has provided an expanded choice of both first and subsequent biologic therapies for patients with rheumatoid arthritis (RA). Understanding when in the treatment pathway TCZ is being used as well as describing its real world effectiveness will provide further evidence on which to frame healthcare decisions. The aims of this analysis are to describe and compare the baseline characteristics and 6 months treatment effectiveness between patients (1) starting TCZ or anti-tumour necrosis factor alpha (anti-TNF) therapy as their first biologic and (2) starting TCZ as a first or as a subsequent biologic.
Methods The British Society for Rheumatology Biologics Register for RA (BSRBR-RA) is an observational prospective cohort study collecting detailed information on RA patients starting biologic therapies in the UK. This analysis included all patients with RA starting either TCZ or an anti-TNF as their first biologic and patients starting TCZ following prior biologic therapy between 1/1/2010 and 31/12/2013. Baseline characteristics were compared between cohorts. Treatment effectiveness was described using the absolute change in DAS28-ESR and EULAR response at 6 months. Ordinal logistic regression models, adjusted by estimated propensity score using inverse probability of treatment weighting (IPTW), were used to compare 6 months EULAR response between cohorts. Missing data were estimated using multiple imputation.
Results 1457 patients starting their first biologic (92 intravenous TCZ, 442 etanercept, 26 infliximab, 301 adalimumab, 596 certolizumab) and 531 patients starting intravenous TCZ as a subsequent biologic therapy were included. There were no significant differences between patients starting TCZ or anti-TNF as their first biologic, with the exception of a shorter disease duration and higher prevalence of pulmonary fibrosis and cancer history among patients starting TCZ (Table). Compared to first line users, patients starting TCZ as a subsequent biologic had longer disease duration, higher HAQ scores, higher corticosteroid use but lower DAS28-ESR. There was no difference in 6 months EULAR response between patients starting TCZ or anti-TNF as their first line therapy (adjusted OR 1.08 (95% CI: 0.67, 1.73). Similar response rates were also seen when TCZ was used as first or subsequent biologic after allowing for differences in baseline characteristics (adjusted OR 0.98 (95% CI: 0.54-1.76).
Conclusions Since 2010, it appears that TCZ is primarily used in the UK as a second-line or later biologic. When TCZ was used as first line, treatment response at 6 months is comparable to anti-TNF. Non-response rates were slightly higher among subsequent versus first line users of TCZ, however, these differences could be accounted for by differences in baseline disease severity.
Disclosure of Interest M. Kihara: None declared, L. Kearsley-Fleet: None declared, R. Davies: None declared, K. Watson: None declared, M. Lunt: None declared, D. Symmons: None declared, K. Hyrich Grant/research support from: Abbvie and Pfizer