Non-Responders to Biologic Disease Modifying Antirheumatic Treatment for Inflammatory Bowel Diseases.

Background and Aim: Biologic disease-modifying antirheumatic drugs (bDMARDs) are effectively used to relieve symptoms in inflammatory bowel diseases (IBD). The study aimed to examine the rate of non-responders to bDMARD treatment in Australian population. Method: Cohort studies using a 10% random sample of the population dispensing medicines under the Australian Pharmaceutical Benefits Scheme (PBS). People aged 18 years and over who initiated bDMARD for IBD in 2019 or 2020 were followed for 12 months. The proportion of non-responders (people who discontinued initial therapy by Week 16 and 40) was determined using Kaplan-Meier survival analysis. Results: There were 522 initiators of bDMARD for Crohn's disease (mean age of 42 years). By Week 16, 15% discontinued initial therapy (primary non-responders); 22% of initial responders discontinued bDMARD by Week 40 (secondary non-responders). The primary non-responder rate was lowest amongst infliximab initiators (6%), and highest for ustekinumab (24%). Infliximab had the lowest (17%) secondary non-responder rate compared to the other biologics, suggesting less loss of response over time.There were 390 initiators of bDMARD for ulcerative colitis (UC) (mean age of 44 years). By Week 16, 25% discontinued initial therapy; 21% of people with initial response discontinued by Week 40. The non-responder rates were lowest amongst vedolizumab initiators (5% for primary and 8% for secondary) and highest amongst adalimumab (50% for primary and 48% for secondary). Conclusion: Comparison between bDMARD agents showed lowest initial non-response and lowest loss of sustained response in infliximab initiators with Crohn's disease and in vedolizumab initiators with UC.