Development and Validation of the Comprehensive Acute Pancreatitis Pain Core Outcome Set (CAPPOS): Study Protocol

Introduction: Acute pancreatitis (AP) is a leading cause of gastrointestinal hospitalizations worldwide, with rising incidence, significant morbidity, and high healthcare costs. Pain, a hallmark symptom of AP, remains inadequately assessed, often relying on unidimensional scales such as visual analogue score, which fail to capture its multidimensional nature. Poorly managed acute pain negatively impacts clinical outcomes, prolongs recovery, and increases the risk of chronic pain syndromes. Comprehensive pain assessment tools specific to AP are lacking, highlighting the need for improved evaluation methods. The proposed study aims to develop and validate the Comprehensive Acute Pancreatitis Pain Outcome Set (CAPPOS) to address this evidence gap. Methods: The CAPPOS initiative follows COMET and COSMIN guidelines. Three systematic reviews will identify pain domains and assessment methods in AP, acute abdominal pain, and post-pancrectomy pain. A consensus process, using a modified Delphi approach, will involve multidisciplinary experts and patients to confirm and define key domains. Measurement tools will be selected for each domain and refined through iterative feedback. Pilot testing with 50 patients will evaluate the feasibility, clarity, and responsiveness to change of the preliminary tool. Validation studies with 200 AP patients will assess structural, content, and criterion validity, reliability, and sensitivity to change, ensuring content validity and clinical utility. Conclusion: CAPPOS will provide a validated, multidimensional core outcome set to optimize pain assessment in AP. It will also facilitate standardized reporting in clinical trials, advancing research and care for AP-related pain.