Early factors associated with the initiation of treatment with biologics in patients with Axial Spondyloarthritis - results from a single centre retrospective cohort study.

Background: Axial Spondyloarthritis (axSpA) refers to a group of rheumatic diseases that mainly affect the axial skeleton. Treatment with Biological Disease Modifying Anti-Rheumatic Drug (bDMARDs) is indicated when low disease activity is not achieved with Non-Steroid Anti-inflammatory Drugs. Certain clinical and socio-demographic features may be predictive of future need for treatment with bDMARDs in a patient with axSpA.

Objectives: To study a population of patients with axSpA and determine whether the presence of certain factors at diagnosis is associated with a later need for biological treatment.

Methods: A single centre retrospective cohort study was conducted comprising 150 patients with axSpA that attended the Rheumatology Outpatient Clinic from January to December 2019. Logistic Multivariate Regression was performed to understand which factors independently contributed to the use of bDMARDs.

Results: Fifty-two patients (34,7%) were under biological treatment. In comparison to the group that was not under treatment with bDMARDs, these were significantly more likely to be hard-workers (57,8% vs 29,7%; p = ,003), to have had elevated C-Reactive Protein at the time of diagnosis (81,6% vs 48,9%; p < ,001), to have had a grade of sacroiliitis at diagnosis greater than 2 (67,4% vs 29,5%; p < ,001) and to have history of enthesitis, (32,7% vs 13,3%; p = ,006). In multivariate regression analysis, only the hard-worker type (OR = 3.09, CI: 1.14 - 8.37; p = .027) and the highest grade of sacroiliitis (OR = 4.41, CI: 1.69 - 11.50; p = .002) were found to be independently associated with the use of bDMARDs.

Conclusion: In this study, the performance of work associated with greater biomechanical stress and the presence of greater structural damage at diagnosis were shown to be associated with the use of bDMARDs. The authors highlight the importance of recognizing these factors that seem to relate to more aggressive disease, with higher use of bDMARDs, thus suggesting a need for a tighter control management strategy in these patients.