AB0816 PREDICTORS OF RESPONSE TO THE FIRST BDMARD IN BIOLOGIC-NAÏVE PATIENTS WITH SPONDYLOARTHRITIS: A COHORT STUDY
Authors: B. M. Fernandes, S. Garcia, F. Oliveira Pinheiro, M. Rato, D. Fonseca, D. Santos Oliveira, A. Martins, F. R. Martins, M. Bernardes, L. Costa
Journal: Annals of the Rheumatic Diseases (2021)

Background: Several markers of response to biologic disease-modifying antirheumatic drugs (bDMARDs) have been identified in Rheumatoid Arthritis. However, data on predictors of response in Spondyloarthritis (SpA) are more limited. Objectives: To identify predictors of response to bDMARDs in a SpA population. Methods: Monocentric retrospective study including all the SpA patients (ASAS classification criteria) followed at our Rheumatology Department, registered in the national database and treated with bDMARD between July 2001 and August 2020. Demographic, clinical and laboratorial data at baseline and disease activity measures at 6 and 12 months of bDMARD were collected. Mann-Whitney U test and chi-square tests were used to the comparison analysis between groups (continuous and categorical variables, respectively) and univariate logistic regression was used in the prediction analysis. Results: A total of 325 patients were included, 178 (54.8%) males, 76 (23.4%) smokers and 164 (50.5%) HLA-B27 positive. Concerning SpA subtypes: 236 (72.6%) had Ankylosing Spondylitis, 31 (9.5%) had Inflammatory Bowel Disease Associated SpA and 58 (17.9%) had Undifferentiated SpA. The mean age at the start of the first bDMARD was 41.7 years (±12.2) and the median disease duration was 12.1 years (0.5-52.7). The mean ASDAS-CPR (Ankylosing Spondylitis Disease Activity Score with C-reactive protein) was 4.0 (±0.8) and most patients (57.2%) exhibited very high disease activity at baseline as evaluated by ASDAS-CRP. Ninety-five (29.2%) patients were taking NSAIDs (nonsteroidal anti-inflammatory drugs) and 131 (40.3%) were under csDMARDs (conventional synthetic disease-modifying antirheumatic drugs), being sulfasalazine the most frequent (28.3%). All patients started iTNF (tumor necrosis factor inhibitors): adalimumab (30.2%) and golimumab (24.6%) were the most frequently started bDMARDs. At 6 and 12 months of bDMARD, 63.5% and 65.7% of the patients had ASDAS response (clinically important improvement or major improvement). Variables that showed statistically significant differences at baseline between those different groups are presented at Table 1. Table 1. Baseline characteristics that showed statistically significant differences at baseline between groups of patients with vs without ASDAS responses at 6 and 12 months of bDMARD. (bDMARD: biologic disease-modifying antirheumatic drug; BMI: body mass index; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate). ASDAS response at 6 months ASDAS response at 12 months yes no p-value yes no p-value Age at start of bDMARD (mean±SD) 39.6±12.2 years 44.2±10.7 years p=0.012 40.7±12.8 years 44.2±10.9 years p=0.035 Age at SpA diagnosis (mean±SD) 32.2±11.1 years 35.8±11.9 years p=0.023 31.3±10.7 years 35.4±11.2 years p=0.010 BMI (mean±SD) 25.7±4.3kg/m 2 28.7±6.0 kg/m 2 p=0.045 25.6±4.3 kg/m 2 28.5±5.7 kg/m 2 p=0.005 CRP (mean±SD) 3.2±3.5 mg/dL 1.1±1.2 mg/dL p&lt;0.001 3.4±3.5 mg/dL 1.4±1.6 mg/dL p&lt;0.001 ESR (mean±SD) 36±22 25±20 p&lt;0.001 38±24 27±17 p=0.001 ASDAS-CRP (mean±SD) 4.1±0.8 3.5±0.4 p&lt;0.001 4.2±0.8 3.6±0.8 p&lt;0.001 HLA-B27+ 61.5% 26% p=0.006 60.1% 44.4% p=0.033 Males 62.3% 35.7% p=0.004 62.3% 37.5% p=0.001 Body mass index (BMI) (OR 0.89 [0.80-0.99], 95% CI) and ASDAS-CRP at baseline (OR 2.8 [1.2-6.6], 95% CI) predicted ASDAS response at 6 months; moreover, only BMI (OR 0.91 [0.83-0.99], 95% CI) predicted ASDAS response at 12 months of bDMARD. Conclusion: Our results demonstrate that a higher baseline disease activity predicts the response to bDMARDs in SpA. Interestingly, BMI at baseline also predicts ASAS response at 6 and 12 monthes of treatment with bDMARD, in line with some data that suggest an association between BMI and disease activity in SpA. Disclosure of Interests: None declared