P873 Ustekinumab Real World Evidence Study (UndieS): Assessing the suitability of patients treated in routine clinical care for participation in the pivotal phase 3 clinical trial

Abstract

Abstract Background Phase 3 randomised controlled trials (RCTs) are recognised as the gold standard for measuring the efficacy of new medicines and are essential for licensing new products. To maximise internal validity, RCTs recruit a highly selected, carefully defined group of participants, whereas patients treated in routine practice are much more heterogeneous. We set out to describe the real-world use of ustekinumab and assess the proportion of treated patients who would have been eligible for the relevant registration studies. Methods UndieS is a UK-based, multicentre, prospective, observational study investigating the effectiveness of ustekinumab in 593 Crohn’s disease patients. Objective evidence of active Crohn’s disease (biochemical or endoscopic) and/or failure or intolerance to another therapy were the only entry criteria. Within the limits of the study, we compared participants’ characteristics with the eligibility requirements of the UNITI clinical trial programme. The pragmatic modified Harvey-Bradshaw Index (mHBI), shown to correlate to CDAI score, was used in UndieS. No endoscopic follow up information was collected. Results 82% of patients treated in this real-world study would not have been eligible for participation in the UNITI programme. Eight RCT eligibility criteria would each be expected to exclude at least 10% of the real-world patient population (figure 1). A low disease activity score was the eligibility criterion most frequently expected to render UndieS participants ineligible for the UNITI programme with 61% of predicted CDAI scores (i.e. estimated from mHBI) falling below the threshold for RCT eligibility, despite 80% of those treated having objective evidence of inflammation and 55% failed/ were intolerant to an alternative therapy. Only 13% of participants were using corticosteroids at baseline. 59% of UndieS participants had previously failed or been intolerant to at least one anti-TNFα medication. For those who would have been ineligible for the RCT based on laboratory tests, an elevated ALT was the commonest abnormality among UndieS participants. The requirements for multiple venepunctures and pregnancy avoidance were the most relevant impediments for UndieS patients, with 28% of females of childbearing potential not willing to agree to the specified conditions. Conclusion Within the limitations of this study, we have demonstrated a significant disparity between participants in phase 3 RCTs and patients treated in routine clinical care. This questions the applicability of efficacy studies to real world clinical practice. Data from high quality, observational studies should complement findings from RCTs to support decision makers. Future work will investigate whether outcomes differ according to RCT eligibility.