Abstract
Objective: To model the estimated disease-modifying effect of etanercept over sulphasalazine in patients with ankylosing spondylitis. Methods: A post hoc analysis of data from the Ankylosing Spondylitis Study Comparing ENbrel and Sulfasalazine Dosed Weekly (ASCEND) study was performed using the Natural History Staggered Start (NHSS) method. A mixed model with a linear effect over time was fitted to the ASCEND data and resampling was performed to generate confidence intervals. Results: At week 16, the total additional improvement in Bath Ankylosing Spondylitis Metrology Index of the etanercept arm over the sulphasalazine arm was 0.62 points, of which 31% (0.19 points) was estimated to be due to disease-modifying effect. Conclusions: The analysis of ASCEND data suggests that etanercept may have a larger disease-modifying effect than sulphasalazine. Further research is needed with more objective measures such as magnetic resonance imaging or X-radiography to confirm these results.