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P148 ANA and Anti-dsDNA antibody enabling the prediction of inflammatory arthritis in inflammatory bowel disease.

de Sousa Magalhães, R.(1,2,3);Lima Capela, T.(1,2,3);Rosa, B.(1,2,3);Moreira, M.J.(1,2,3);Cotter, J.(1,2,3);

(1)Hospital da Senhora da Oliveira- em Guimarães., Gastroenterology Department, Guimarães, Portugal;(2)ICVS/3B’s- PT Government Associate Laboratory, ICVS/3B’s- PT Government Associate Laboratory, Guimarães/Braga, Portugal;(3)Life and Health Sciences Research Institute ICVS- School of Medicine, University of Minho, Braga, Portugal

Background

Inflammatory arthritis is frequent as an extraintestinal manifestation of IBD, as well as a paradoxical reaction to biological treatment. Anti-nuclear antibody (ANA) and Anti-dsDNA antibody have been associated with inflammatory arthritis. We aim to assess the correlation between the presence of ANA and Anti-dsDNA antibody and the diagnosis of inflammatory arthritis in patients with IBD under biological treatment.

Methods

We present a cohort study, including IBD patients under biological treatment, presenting at least a treatment session in the first 2 months of 2020. Data was gathered from medical records, laboratorial analysis, namely ANA and Anti-dsDNA, were collected in the treatment session, and every patient posteriorly answered telephonically validated questionnaires to assess the presence of inflammatory arthritis, the outcome variable. A univariate analysis followed by a multivariate logistic regression, including statistically significant variables, tested the correlation towards inflammatory arthritis. A ROC curve tested the performance of the final model.

Results

We included 122 patients, 64 (52.5%) were women, and the mean age was 39 years old. Eighty-six (70.5%) patients presented Crohn’s Disease and 36 (29.5%) Ulcerative Colitis. A hundred (82%) patients were under Infliximab, 21 under Vedolizumab (17.2%) and only 1(0.8%) under Adalimumab. Thirty-three patients (27%) met questionnaire criteria for inflammatory arthritis, either peripheric or axial. The variables age, ANA and ANA’s title, age at IBD diagnosis and number of symptomatic articulations involved were associated with the presence of inflammatory arthritis. The multivariate model including ANA (OR 4.149 [1.03-16.711] p=0.045); number of articulations involved (OR 2.683 [1.783-4.038] p<0.001) and higher age at IBD diagnosis, accurately identified patients with diagnosis of inflammatory arthritis (ROC AUC 0.957 [0.926-0.987] p<0.001). A sub-analysis correlating ANA and the presence of inflammatory arthritis after biological initiation showed a statistical tendency (OR 2.231 [0.908-5.478] p<0.08).

Conclusion

The presence of ANA antibodies and a higher number of symptomatic articulations involved independently increased the rate of inflammatory arthritis diagnosis in up to 4 times, in a cohort of patients with IBD under biological treatment.  The inclusion in a multivariate model displayed an excellent accuracy and performance towards the diagnosis of inflammatory arthritis. ANA antibodies together with validated questionaries may aid in the identification of IBD patients suffering from inflammatory arthritis.

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