Evaluation of the change in structural radiographic sacroiliac joint damage after 2 years of etanercept therapy (EMBARK trial) in comparison to a contemporary control cohort (DESIR cohort) in recent onset axial spondyloarthritis

Objective To compare 2 years of radiographic sacroiliac joint (SIJ) changes in patients with recent onset axial spondyloarthritis (axSpA) receiving etanercept in a clinical trial (EMBARK) to similar patients not receiving biologics in a cohort study (DESIR). Methods Endpoints were changes at week 104 per the modified New York (mNY) grading system in total SIJ score (primary endpoint) and net percentage of patients with progression defined three ways. Treatment effect was analysed with and without adjustment for baseline covariates. Results At 104 weeks, total SIJ score improved in the etanercept group (n=154, adjusted least-squares mean change: -0.14) and worsened in the control group (n=182, change: 0.08). The adjusted difference between groups (etanercept minus control) was -0.22 (95% CI -0.38 to -0.06), p=0.008. The net percentage of patients with progression was significantly lower in the etanercept versus the control group for two of three binary endpoints: -1.9% versus 1.6% (adjusted difference for etanercept minus control: -4.7%,95% CI -9.9 to 0.5, p=0.07) for change in mNY criteria; -1.9% versus 7.8% (adjusted difference: -18.2%,95% CI -30.9 to -5.6, p=0.005) for change 1grade in 1SIJ; and -0.6% versus 6.7% (adjusted difference: -16.4%,95% CI -27.9 to -5.0, p=0.005) for change 1grade in 1SIJ, with shift from 0 to 1 or 1 to 0 considered no change. Conclusion Despite the slow radiographic SIJ progression rate over 2 years in axSpA, this study suggests a lower rate of progression in the SIJ with etanercept than without anti-tumour necrosis factor therapy. Trial registration numbers NCT01258738, NCT01648907; Post-results.