AB0878 Higher vitamin D serum level is associated with a better clinical response to bDMARDs in patients with axial spondyloarthritis

BackgroundVitamin D deficiency has been shown to be associated with higher disease activity and severity of several inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease and spondyloarthritis (SpA). It is, however, unknown if vitamin D level might affect the response to treatment with biologic disease-modifying anti-rheumatic drugs (bDMARDs) in patients with SpA.ObjectivesTo investigate the association between vitamin D serum levels and the response to a bDMARD therapy in patients with axial SpA.MethodsPatients with a radiographic axial SpA (r-axSpA), fulfilling the modified New York criteria and starting a bDMARD therapy were recruited between 2015 and 2019 in an extension of the prospective German Spondyloarthritis Inception Cohort (GESPIC-AS). All patients were required to have at inclusion high disease activity (BASDAI >=4 and/or ASDAS >=2.1) despite previous treatment with nonsteroidal anti-inflammatory drugs. Demographics, patient clinical characteristics and vitamin D serum levels were collected at baseline. Disease activity measures (BASDAI, CRP, ASDAS) were assessed at baseline and after 6 months of bDMARD treatment. Vitamin D deficiency was defined as serum level of 25-hydroxyvitamin D < 20 ng/mL. A multivariable regression analysis was performed to determine the association between vitamin D serum level at baseline and the treatment response as defined by BASDAI and ASDAS change scores at month 6 as compared to baseline.ResultsA total of 129 patients with r-axSpA were included in the study. No patient took supplements of vitamin D at baseline. Patients had an average age (mean±SD) of 36.5±10.5 years, 64.3% were males and 86.6% were HLA-B27 positive. The prevalence of vitamin D deficiency in our cohort was 54.3%. Patient characteristics and disease activity were comparable with regard to the presence of vitamin D at baseline (Table 1); with the exception of body mass index (BMI), which was higher in patients with vitamin D deficiency. In the multivariable linear regression analysis, baseline serum level of vitamin D was independently and significantly associated with higher change in BASDAI and ASDAS (Figure 1).Table 1.Baseline characteristics of patients with radiographic axial SpA (n=129) according to vitamin D levels at baseline.Patients with vitamin D deficiency (Patients with normal levels of vitamin Dn=59Age, years36.6±11.036.3±10.0Male sex46 (65.7)37 (62.7)BMI, kg/m226.0±4.5*24.0±3.8Smoking, ever41 (58.6)29 (49.2)Winter and Spring, n (%)33 (47.1)23 (39.0)Symptom duration, years11.5±11.310.3±7.1HLA-B27 positive62 (88.6)50 (84.7)Uveitis ever17 (24.3)12 (20.3)Psoriasis ever11 (15.7)7 (11.9)IBD ever, n (%)2 (2.9)7 (11.9)CRP, mg/L12.9±19.313.9±15.3BASDAI5.7±1.45.4±1.4ASDAS3.4±0.83.5±0.8BASFI4.6±2.24.4±1.9BASMI3.1±1.52.7±1.3NSAID intake, current50 (71.4)45 (76.3)DMARDs intake, ever9 (12.9)6 (10.2)TNFi naive55 (78.6)47 (79.7)Corticoids intake, current5 (7.1)2 (3.4)*p value All numerical variables were presented as mean±SD, all categorical variables were presented as n (%).BMI, body mass index; CRP, C-reactive protein; DMARD, disease-modifying antirheumatic drug; IBD, inflammatory bowel disease; NSAID, nonsteroidal anti-inflammatory drug; TNFi, tumor necrosis factor inhibitor.Figure 1.Association between the response to bDMARDs (change in BASDAI and ASDAS after 6 months) and level of vitamin D at baseline in patients with radiographic axial SpA in the multivariable regression analysis.ConclusionHigher vitamin D levels at baseline may predict a better treatment response to bDMARDs in patients with r-axSpA. It has to be shown, however, if vitamin D supplementation might result in a better treatment response in axial SpA.Disclosure of InterestsNone declared