P0920Weighing up the evidence - JAK inhibitors do not cause drug-class specific gain of weight in Inflammatory Bowel Disease patients

Background The JAK inhibitors (JAKi) tofacitinib, filgotinib and upadacitinib are licensed in the UK for use in Inflammatory Bowel Disease (IBD) - upadacitinib in Crohn’s disease (CD), and all three in ulcerative colitis (UC). Change in weight has been reported in a meta-analysis of JAKi usage in IBD and other conditions, demonstrating weight gain in 5.9% of patients using these drugs with a mean increase of 8.6kg after >1year of treatment.1 We aimed to assess the effect of the drug class on weight in our population using JAKi by comparing to a matched cohort of those using infliximab (IFX). Methods The NHS Greater Glasgow and Clyde IBD database was used to identify patients who had received a JAKi, and an age- and sex-matched cohort who had received IFX, with at least 12 months of follow up. Electronic records were used to collect retrospective data on the patients’ weight at induction of therapy, at 3 months (+/- 4 weeks), 6 months (+/- 4 weeks) and 12 months (+/- 4 weeks). Results 63 JAKi patients with a baseline weight and at least 12 months of follow up were identified (34 upadacitinib, 12 tofacitinib, 17 filgotinib) along with an age- and sex-matched cohort of 63 IFX patients. 46/63 JAKi patients and 59/63 IFX patients had at least one follow up weight measurement in the follow up period. Weight at induction was similar (JAKi mean 80.7kg, range 48.2-115.6; IFX mean 77.1kg, range 42-153, p=.253). An increase in weight was seen within both groups across the 12 month follow up period (JAKi mean change +4.3kg, range -11-+19.4; IFX mean change +3.5kg, range -11-+16.1). 78.2% of the JAKi group and 72.8% of the IFX group gained weight. There were no significant differences in change in weight from baseline at 3 months, 6 months, or 12 months between the two groups. There were no differences in weight change between genders. Those with CD treated with JAKi showed a greater increase in weight in the first 6 months than those treated with IFX (p=.023), however there was no significant difference between the groups at 12 months. No differences in weight change were seen between those with UC using JAKi and using IFX. There were also no differences in weight change between individual JAKi and IFX. Conclusion In our cohort, there were no significant differences in weight change between those using JAKi or IFX for IBD. Modest weight gain was seen in each cohort over 12 months of follow-up, although in a much greater proportion of patients than has previously been reported. Weight gain may reflect improvement in disease control, though the relationship between weight and disease activity in IBD is complex. With increased usage of JAKi for IBD, our findings may be of reassurance for clinicians and patients alike. Reference: Xiong G, Yu E, Heung M et al. Weight gain secondary to the use of oral Janus kinase inhibitors: A systematic review and meta-analysis. JAAD International. 2025;19:1-9. https://doi.org/10.1016/j.jdin.2024.11.009 Conflict of interest: Dr. Brownson, Emily: No conflict of interest Al-Senani, Tasnim: No conflict of interest Macdonald, Jonathan: