Statistical analysis plan: CT prediction score and anatomical discovery for internal herniation after Roux-en-Y gastric bypass (v1.0)

Pre-specified statistical analysis plan for an existing retrospective cohort (UZ Leuven, ethics approval MP029637) of 177 patients after Roux-en-Y gastric bypass who underwent CT and surgical exploration. The plan covers development and internal validation of a CT-based point score for internal herniation, exploratory analysis of detailed anatomical CT signs for Petersen and entero-enteral hernia, and a descriptive cohort explorer. Data were collected and partially analysed (univariable accuracy) before registration; this prior knowledge is disclosed in section 2 of the plan. The file is under embargo until publication of the study.