Adjudication of a primary trial outcome: Results of a calibration exercise and protocol for a large international trial

Background: Ascertainment of the severity of the primary outcome of upper gastrointestinal (GI) bleeding is integral to stress ulcer prophylaxis trials. This protocol outlines the adjudication process for GI bleeding events in an international trial comparing pantoprazole to placebo in critically ill patients (REVISE: Re-Evaluating the Inhibition of Stress Erosions). The primary objective of the adjudication process is to assess episodes submitted by participating sites to determine which fulfil the definition of the primary efficacy outcome of clinically important upper GI bleeding. Secondary objectives are to categorize the bleeding severity if deemed not clinically important, and adjudicate the bleeding site, timing, investigations, and treatments. Methods: Research coordinators follow patients daily for any suspected clinically important upper GI bleeding, and submit case report forms, doctors' and nurses' notes, laboratory, imaging, and procedural reports to the methods center. An international central adjudication committee reflecting diverse specialty backgrounds conducted an initial calibration exercise to delineate the scope of the adjudication process, review components of the definition, and agree on how each criterion will be considered fulfilled. Henceforth, bleeding events will be stratified by study drug, and randomly assigned to adjudicator pairs (blinded to treatment allocation, and study center). Results: Crude agreement, chance-corrected agreement, or chance-independent agreement if data have a skewed distribution will be calculated. Conclusions: Focusing on consistency and accuracy, central independent blinded duplicate adjudication of suspected clinically important upper GI bleeding events will determine which events fulfil the definition of the primary efficacy outcome for this stress ulcer prophylaxis trial. Registration: NCT03374800 (REVISE: Re-Evaluating the Inhibition of Stress Erosions).