FRI0409 FEMALE ANKYLOSING SPONDYLITIS PATIENTS HAVE A SUBSTANTIALLY LOWER TNFI TREATMENT RESPONSE THAN MEN

Abstract

Background: Accumulating data revealed difference in treatment efficacy in biologicals in women with axial spondyloartritis (axSpA) (1). Objectives: The aim of this study was to assess gender differences in TNF inhibitor treatment response up to a five year biological treatment Methods: Radiographic axSpA patients (AS) were recruited from the Amsterdam Spondyloarthritis cohort (the AmSpA cohort) of the VU University center and Reade. This prospective, observational cohort study included consecutive AS patients who were treated with TNF inhibitors (TNFi) (infliximab, adalimumab, etanercept or golimumab). Data of this cohort were collected between January 2000 until December 2018. Inclusion criteria were: AS diagnosis according to the modified New York criteria and start with a first TNFi. Patients were evaluated at baseline, three months, six months and once yearly up to five years follow-up. Disease activity was determined with the Ankylosing Spondylitis Disease Activity Score (ASDAS) and the Bath Ankylosing Spondyloartritis Index (BASDAI). Generalized equation estimation (GEE) analyses were performed to correct for multiple measurements. Linear ad logistic regression analyses were performed to assess the delta difference between baseline and 1 year. Results: 389 AS patients were included in the AmSpA cohort. Thirty-three of these 389 patients were excluded since they were not TNFi naive or their treatment status was unknown (7.5%), of whom the majority was female: 14/135 females (10.5%) vs. 15/250 males (6.0%). Overall 182 patients (51.1%) dropped out over the study period, with a statistically significant higher percentage of females: 46.4% vs. 60.3% (OR= 1.8, 95%CI [1.4;2.4] p= 0.01). Adjusted models for ASDAS-CRP at six and twelve months showed that female patients had a 1.4 and 1.5 point higher mean ASDAS-CRP (b = 1.4, 95%CI [0.17;2.5] p=0.03) and (b = 1.5, 95%CI [0.41;2.8] p=0.007), respectively, compared to males. Adjusted models for BASDAI at six and twelve months showed no statistical significant differences for gender. After one year up to five year follow-up, no statistical significant gender differences were observed in both the mean BASDAI and mean ASDAS-CRP Conclusion: In radiological axial SpA, female patients had significantly lower level of TNFi treatment response at six and twelve months on the ASDAS-CRP and had a higher drop-out rate compared to males. This strongly indicates an important gender difference in especially the twelve first months of TNFi treatment.