P493 Do antiTNF or Ustekinumab trough levels correlate with joint extraintestinal manifestations activity in Inflammatory bowel disease patients?
Authors: Madero Velázquez L , Zapater P , Mira C , Jovani V , Andrés M , Aguas M , Vicens E , Barreiro-de Acosta M , Pérez-Pampín E , Porto-Silva M , Zabana Y , Pujol M , Herreros B , Ojeda A , Noguera J R , Rainieri L , Bernal L , Belen O , Moreno V , Cameo J , Sempere L , Más-Serrano P , Gutierrez Casbas A 
Published: January 2024

Abstract

Background
Inflammatory spondyloarthritis(SpA) are the most common extraintestinal manifestations (EIM) associated to inflammatory bowel disease (IBD), with a prevalence of 20-50% for axial SpA(axSpA) and 5-20% for peripheral(pSpA). AntiTNF is the optimal therapy in axSpA intolerant or refractory to NSAIDs, also effective in pSpA. An optimal trough level has not been yet established in this clinical setting. Aim, to evaluate the correlation between antiTNF and UST trough levels and joint EIM activity in IBD patients.

Methods
Prospective, multicenter,cohort study. IBD patients diagnosed with articular EIM under antiTNF or Ustekinumab(UST) for at least 6 months were included. Blood samples were obtained just before administering the drug(trough levels), and a simultaneous evaluation by a rheumatologist and a gastroenterologist, was performed. Definitions: inactive AxSp=ASDAS-CRP&lt;1.3 and BASDAI&lt;2, inactive pSp=arthritis, enthesitis and dactylitis=0, active AxSp=ASDAS-CRP &gt;2.1 and BASDAI&gt;4, active pSp= artritis, entesitis o dactilitis &gt; 0. Aim, to evaluate the correlation between antiTNF and UST trough levels and joint EIM activity in IBD patients.

Results
A total of 135 patients were included: mean age 51 ± 15, 59 (43.7%)women), 80% CD. 60(44.4%) patients presented axSpA, 50(37%) pSpA and 25(18.5%) mixed. 12(8.9%) had active IBD. Table 1 summarizes the patients' main demographic and clinical characteristics distributed by SpA activity. Fifty-three(39%) were on infliximab (IFX), 61(45.2%), on adalimumab (ADA) and 22 (16.3%) on UST treatment. NSAIDs treatment(12.7% vs 3.1%, p&lt;0.05), higher fecal calprotectin(FC)(486 ± 709 vs 228.2 ± 297, p&lt;0.05), and the prior use of biologics(33.8% vs 17.6%, p&lt;0.05) were more frequent among active vs inactive SpA patients. No differences between IFX(7.05 ± 4.16 vs 5.79± 4.05, p=ns), ADA(7.98 ± 4.20 vs 9.51 ± 6.15 p=ns) and UST levels(3.39 ± 3.47 vs 3.08 ±2.69, p=ns), were found between active and inactive SpA patients, even when were distributed by type of SpA(axSpA/mixed and pSpA). Body mass index(b:-0,29, p=0.01)FC(b:-0,28, p=0.01), and intensified therapy(b:-0,28, p=0.01) were associated to higher IFX levels in the whole SpA cohort.
Patients with axSpA or mixed were articular active more frequently than pSpA patients(82% vs 18%, p &lt;0.05). IBD activity was correlated to articular activity only among pSpA patients(2% active IBD in inactive pSpA vs 20% active IBD in active pSpA patients, p=0.03).

Conclusion
AntiTNF and UST trough levels are not correlated to joint activity in patients with IBD and SpA. In our study more than 80% of patients with active SpA were inactive regarding IBD. Only pSpA patients presented correlation between IBD and articular activities.