The 2 + 1 paradigm: an efficient algorithm for central reading of Mayo endoscopic subscores in global multicenter phase 3 ulcerative colitis clinical trials

Despite its importance and potential impact in clinical trials, central reading continues to be an under-represented topic in the literature about inflammatory bowel disease (IBD) clinical trials. Although several IBD studies have incorporated central reading to date, none have fully detailed the specific methodology with which the reads were conducted. Here we outline key principles for designing an efficient central reading paradigm for an ulcerative colitis (UC) study that addresses regulatory, operational and clinical expectations. As a step towards standardization of read methodology for the growing number of multicenter phase 3 clinical trials in IBD, we have applied these principles to the design of an optimal read methodology that we call the '2 + 1 paradigm.' The 2 + 1 paradigm involves the use of both site and central readers, validated scoring criteria and multiple measures for blinding readers, all of which contribute to reducing bias and generating a reliable endoscopic subscore that reflects endoscopic disease severity. The paradigm can be utilized while maintaining a practical workflow compatible with an operationally feasible clinical trial. The 2 + 1 paradigm represents a logical approach to endoscopic assessment in IBD clinical trials, one that should be considered attractive to prospective sponsors, contract research organizations, key opinion leaders and regulatory authorities and be ready for implementation and further evaluation.