An Evaluation of Factors Contributing to Primary Nonresponse to Biological Therapy in Patients with Spondyloarthropathy: A Retrospective Cohort Study

Abstract

Background/Aims: Primary nonresponse to biological therapy in patients with spondyloarthropathy (SpA) is a considerable challenge. This study sought to identify the factors associated with primary nonresponse to biological therapy in a cohort of patients diagnosed with SpA.

Materials and Methods: A retrospective analysis was performed on 261 patients with SpA who underwent at least 1 biological therapy. The incidence of primary nonresponse to any biological treatment was evaluated, and various clinical and demographic factors were analyzed for their potential associations with treatment outcomes.

Results: The study found that the frequency of primary nonresponse to any biological disease–modifying antirheumatic drugs (bDMARDs) was 15.3% in the study population. In the logistic regression analysis of baseline parameters, presentation with arthritis at diagnosis was identified as a significant predictor of primary nonresponse (odds ratio: 2.113, 95% CI: 1.069-4.175, P = .031). Beyond this baseline predictor, primary non-responders significantly differed from responders by having higher frequencies of concomitant fibromyalgia (FMS) treatment (P = .047) and higher terminal C-reactive protein (CRP) levels (P = .030), as well as variations in acute-phase reactants, presence of psoriasis or enthesitis at diagnosis, and treatmentrelated factors such as bDMARDs duration.

Conclusion: This study identifies baseline arthritis as a significant predictor of primary nonresponse to bDMARDs in SpA patients. Additionally, the presence of FMS and elevated CRP levels during follow-up are key clinical characteristics associated with the non-responder phenotype. These findings highlight the need for more objective assessment tools to distinguish true biological treatment failure from comorbid pain syndromes and the influence of disease phenotypes.

Cite this article as: Oğuz Kökoğlu E, Kaplan H, Kızıltepe M, Kahraman Denizhan T, Cengiz CB, Şenel AS. An evaluation of factors contributing to primary nonresponse to biological therapy in patients with spondyloarthropathy: A retrospective cohort study. ArchRheumatol. Published online April 10, 2026. doi: 10.5152/ArchRheumatol.2026.25237.