TNF Blockers and Reduced Spinal Radiographic Progression in Ankylosing Spondylitis

Data suggest that the use of tumor necrosis factor inhibitor (TNFi) therapy in patients with ankylosing spondylitis (AS) has an inhibitory effect on spinal radiographic progression if treatment continues for 2 years, and that this effect is mediated by a reduction in disease activity, according to a recent study published in Annals of the Rheumatic Diseases.¹

Swiss researchers enrolled 432 patients with AS from the Swiss Clinical Quality Management cohort who had ≥10 years of follow-up in the study and conducted radiographic assessments every 2 years. Two trained readers scored all available radiographs for each participant, based on the modified Stoke Ankylosing Spondylitis Score (mASSS).² They also examined the relationship between TNFi use prior to a 2-year interval and progression within that interval. The Ankylosing Spondylitis Disease Activity Score (ASDAS) value was viewed to mediate the effect of TNFi therapy on disease progression.

An analysis included 616 radiographic intervals, with radiographic progression defined as an increase in mASSS over a 2-year interval. The mean mASSS increase reported was 0.9 ± 2.6 units over 2 years. Prior use of TNFi therapy significantly decreased the risk for radiographic progression by 50% (odds ratio [OR], 0.50; 95% CI: 0.28-0.88; P =.02). Baseline mASSS values and male gender were both significantly associated with an increase in radiographic damage after 2 years (OR, 1.06; 95% CI: 1.04-1.09; P <.001 and OR, 2.16; 95% CI: 1.09-4.30; P =.03, respectively).

Although no statistically significant direct effect of TNFi treatment on progression was reported in an analysis including time-varying ASDAS (OR, 1.61; 95% CI: 0.34-1.08;
P =.09), the indirect effect observed, via a reduction in ASDAS, was significant (OR, 0.75; 95% CI: 0.59-0.97; P =.01).

The investigators concluded that TNFi therapy in patients with AS has a clinically relevant inhibitory effect on spinal radiographic progression if the intervention is continued for a minimum of 2 years. This effect has been shown to be linked to a decrease in disease activity.

References

1. Molnar C, Scherer A, Baraliakos X, et al; on behalf of the Rheumatologists of the Swiss Clinical Quality Management Program. TNF blockers inhibit spinal radiographic progression in ankylosing spondylitis by reducing disease activity: results from the Swiss Clinical Quality Management cohort [published online September 22, 2017]. Ann Rheum Dis. doi: 10.1136/annrheumdis-2017-211544.
2. Creemers MC, Franssen MJ, van’t Hof MA, Gribnau FW, van de Putte LB, van Riel PL. Assessment of outcome in ankylosing spondylitis: an extended radiographic scoring system. Ann Rheum Dis. 2005;64(1):127-129.