Patients enrolled in randomised controlled trials (RCTs) may differ from the target population due to restricted eligibility criteria.
To compare treatment response to biologics in routine practice for children with inflammatory bowel diseases (IBD) who would and would not have been eligible for enrolment in the regulatory RCT of the same drug.
We enrolled children with IBD who initiated adalimumab, infliximab, vedolizumab or ustekinumab. The eligibility criteria as defined in the RCT of the corresponding biologic were applied to each patient. The primary outcome was 12-month steroid-free remission (SFR) without switching biologics or undergoing surgery.
We screened 289 children (198 [68%] with Crohn's disease [CD], 91 [32%] with ulcerative colitis [UC]) with 326 initiations of biologics. Only 62 of 164 (38%) children with moderate-to-severe disease would have been eligible for inclusion in the original RCTs. The SFR rate was higher in the eligible children (51%) than in the ineligible children (31%; OR 2.3 [95%CI 1.2-4.5]; p = 0.01). The main exclusion criterion was prohibited previous therapies (47%). Ineligible CD patients were older, more often had a family history of IBD and had higher levels of CRP than eligible children; in UC there were no differences between the groups.
Most children with IBD who initiate biologics would not have been eligible to be included in the corresponding regulatory RCTs. The outcomes of ineligible patients were worse than for eligible patients. Results from RCTs should be interpreted with caution when applied to clinical practice.