The Abdominal Pain Unit (APU). Study protocol of a standardized and structured care pathway for patients with atraumatic abdominal pain in the emergency department: A stepped wedged cluster randomized controlled trial.

This study aims to improve emergency department (ED) care for patients suffering from atraumatic abdominal pain. An application-supported pathway for the ED will be implemented, which supports quick, evidence-based, and standardized diagnosis and treatment steps for patients with atraumatic abdominal pain at the ED. A mixed-methods multicentre cluster randomized controlled stepped wedge trial design will be applied. A total of 10 hospitals with EDs (expected n = 2.000 atraumatic abdominal pain patients) will consecutively (every 4 months) be randomized to apply the intervention. Inclusion criteria for patients are a minimum age of 18 years, suffering from atraumatic abdominal pain and being insured with a German statutory health insurance. Primary outcomes: acute pain score at time of discharge from ED, duration of treatment at the ED, patient-reported satisfaction. Secondary endpoints include patient safety and quality of care parameters, process evaluation parameters, and costs and cost-effectiveness parameters. Quantitative data will be gathered from patient-surveys, clinical records, and routine data from hospital information systems as well as from a participating German statutory health insurance. Descriptive and analytic statistical analysis will be performed to provide summaries and associations for primary patient-reported outcomes, process measures, quality measures, and costs. Qualitative data collection consists of participatory patient observations and semi-structured expert interviews, which will be inductively analysed. Findings will be disseminated in publications in peer-reviewed journals, on conferences, as well as via a project website. To ensure data protection, appropriate technical and organisational measures will be taken. Trial registration: DRKS00021052.