Study of Treatment with Intensified Omeprazole to Prevent High-Output Stoma—A Protocol for a Randomized, Parallel-Group, Open-Label, Superiority Trial in Adults Undergoing Ileostomy (STOP-HOS-1)

Introduction: High-output stoma (HOS) is a frequent and morbid complication following ileostomy formation. Proton pump inhibitors (PPIs) may reduce intestinal secretions, but no randomized trial has yet tested whether intensified intravenous omeprazole treatment prevents or mitigates early postoperative HOS. We aim to determine whether intensified PPI dosing reduces early postoperative ileostomy output compared with standard dosing. Methods and Analysis: STOP-HOS-1 is a randomized, parallel-group, open-label, superiority trial conducted at two academic centers in Poland. The target sample size is 100 adults undergoing the formation of a loop or end ileostomy. Participants will be randomized 1:1 to receive either: intensified omeprazole group—80 mg IV loading dose, followed by 40 mg IV twice daily through postoperative day (POD) 10, or standard omeprazole group—40 mg IV once daily through POD 10. The primary outcome is mean ileostomy output (mL/24 h) across POD 1–3. A ≥250 mL/day reduction is prespecified as clinically meaningful. Key secondary outcomes include: incidence of HOS (≥1000 mL/day for ≥3 consecutive days or ≥1400 mL on any single day), time to output stabilization (<1400 mL/day for 3 consecutive days), dehydration-related complications (hyponatremia, hypokalemia, acute kidney injury), length of hospital stay and 30-day readmission rate. The primary analysis will follow the intention-to-treat principle. One interim safety analysis is planned after enrollment of the first 20 patients. Discussion: Although PPIs are commonly used to reduce ileostomy output, high-quality evidence in the early postoperative setting is lacking. STOP-HOS-1 targets the critical period when output is most variable, and complications are most frequent, using a pragmatic randomized design and an objective, clinically meaningful primary endpoint. Conclusions: STOP-HOS-1 will provide the first randomized evidence on whether intensified postoperative PPI therapy reduces early ileostomy output and HOS-related morbidity, informing future standards of care.