Utility of Abdominal Drain in Gastrectomy (ADiGe) Trial: study protocol for a multicenter non-inferiority randomized trial

Background: Prophylactic use of abdominal drain in gastrectomy has been questioned in the last 15 years, and a 2015 Cochrane meta-analysis on four RCTs concluded that there was no convincing evidence to the routine drain placement in gastrectomy. Nevertheless, the authors evidenced the moderate/low quality of the included studies and highlighted how 3 out of 4 came from Eastern countries. After 2015, only retrospective studies have been published, all with inconsistent results. Methods: ADiGe (Abdominal Drain in Gastrectomy) Trial is a multicenter prospective randomized non-inferiority trial with a parallel design. It aimed to verify whether avoiding routine use of abdominal drain is burdened with complications, particularly an increase in postoperative invasive procedures. Patients with gastric cancer, scheduled for subtotal or total gastrectomy with curative intent, are eligible for inclusion, irrespective of previous oncological treatment. The primary composite endpoint is reoperation or percutaneous drainage procedures within 30 postoperative days. The primary analysis will verify whether the incidence of the primary composite endpoint is higher in the experimental arm, avoiding routine drain placement, than control arm, undergoing prophylactic drain placement, in order to falsify or support the null hypothesis of inferiority. Secondary endpoints assessed for superiority are overall morbidity and mortality, Comprehensive Complications Index, incidence and time for diagnosis of anastomotic and duodenal leaks, length of hospital stay, and readmission rate. Assuming one-sided alpha of 5%, and cumulative incidence of the primary composite endpoint of 6.4% in the control arm and 4.2% in the experimental one, 364 patients allow to achieve 80% power to detect a non-inferiority margin difference between the arm proportions of 3.6%. Considering a 10% drop-out rate, 404 patients are needed. In order to have a balanced percentage between total and subtotal gastrectomy, recruitment will end at 202 patients for each type of gastrectomy. The surgeon and the patient are blinded until the end of the operation, while postoperative course is not blinded to the patient and caregivers. Discussion: ADiGe Trial could contribute to critically re-evaluate the role of prophylactic drain in gastrectomy, a still widely used procedure. Trial registration: Prospectively registered (last updated on 29 October 2020) at ClinicalTrials.gov with the identifier NCT04227951.