Incidence and predictors of demyelinating disease in spondyloarthritis: data from a longitudinal cohort study.

To investigate the incidence of demyelinating disease (DD) among spondyloarthritis (SpA) patients and identify risk factors that predict DD in this patient population. Axial SpA (axSpA) and psoriatic arthritis (PsA) patients were identified from a longitudinal cohort database. Each group was analysed according to the presence or absence of DD. Incidence rates (IR) of DD were obtained with competing risk analysis. Cox regression analysis with Fine and Grey's method was used to evaluate predictors of DD development. Among 2260 patients with follow-up data, we identified 18 DD events corresponding to an average IR of 31 per 100 000 persons per year for SpA. The IR of DD at 20 years was higher in axSpA than in PsA (1.30% vs 0.13%, p= 0.01). The risk factors retained in the best predictive model for DD development included ever- (versus never-) smoking (HR 2.918, 95% CI 1.037-8.214, p= 0.0426), axSpA (versus PsA) (HR 8.790, 95% CI 1.242-62.182, p= 0.0294), and presence (versus absence) of IBD (HR 5.698, 95% CI 2.083-15.589, p= 0.0007). History of TNFi therapy was not a predictor of DD. The overall incidence of DD in this SpA cohort was low. Incident DD was higher in axSpA than in PsA. A diagnosis of axSpA, the presence of IBD, and ever-smoking predicted the development of DD. History of TNFi use was not found to be a predictor of DD in this cohort.

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