Background Treatment with Tumor Necrosis Factor inhibitors (TNFi) has improved the outcome of patients with ankylosing spondylitis (AS) but it is currently unknown, if response varies between different TNFi. One systemic review could not find a significant difference in clinical response and adverse events (AE) between adalimumab (ADL) and etanercept (ETN) in AS patients .
Objectives To compare rates of drug survival and clinical response during 2-years of follow-up in patients with AS treated with ETN or ADL in routine care.
Methods Two-hundred-forty-nine consecutive AS patients previously unexposed to TNFi were treated with ETN (164) or ADL (85). Treatment allocation was at the discretion of the treating rheumatologist. Clinical parameters were measured at each time point. Discontinuation was due to inefficacy on the drug, AE, lost to follow up, pregnancy wish and other reasons. Disease activity was assessed by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Response was defined as an improvement of BASDAI with 50% or as a 2 point drop compared to baseline. Data is corrected for baseline C-reactive protein, methotrexate use, BASDAI and body mass index. We imputed missing data by using last observation carried forward to assess mean BASDAI and BASDAIresponse at 2 years in patients who discontinued ETN or ADL prematurely.
Results A total of 57 (22.9%) patients discontinued the drug, 28 (32.9%) patients discontinued ADL and 29 (17.7%) patients ETN. Cox-regression analysis demonstrated a significant difference in survival rate between discontinuation of the drug in the ADL patients compared to ETN patients; Hazard Ratio (HR) 2.09 (95% CI 1.25–4.50) p=0.005 (see figure) corrected for confounding; HR: 2.65 (95% CI 1.46–4.80) p=0.001. An independent t-test shows no difference at 2-years of follow-up between the ADL and the ETN patients in mean BASDAI; 3.5 (SD±2.5) respectively 4.1 (SD±2.1) p=0.336. Moreover, no difference between the ADL and the ETN patients was found in BASDAIresponse; 17 out of 30 (56.6%) reached BASDAI response at 2 year in patients treated with ADL compared to 73 out of 115 (63.5%) in patients treated with ETN; p=0.493.
Conclusions No difference was found in BASDAI or BASDAIresponse at a 2-year follow up. AS patients using ETN had a higher drug survival in the first 2 years of the treatment compared to AS patients using ADL. However, this study is not designed as a head-to-head trial, which has the risk of a selection bias.
Cochrane Database Syst Rev. 2015 Apr 18;4: CD005468
Disclosure of Interest J. Ruwaard: None declared, M. l'Ami: None declared, A. Marsman Speakers bureau: Pfizer, E. Kneepkens Speakers bureau: Pfizer, I. van der Horst-Bruinsma Grant/research support from: AbbVie, Pfizer, Consultant for: MSD, Speakers bureau: Pfizer, MSD, Abbvie, UCB and BMS, C. van Denderen: None declared, M. Nurmohamed Grant/research support from: AbbVie, BMS, Pfizer, UCB, Roche, Consultant for: Abbott, BMS, Pfizer, Roche, Speakers bureau: AbbVie, Pfizer, Roche, G. Wolbink Grant/research support from: Pfizer, Speakers bureau: Pfizer, Amgen, Abbvie, UCB and BMS