IMPORTANCE The incidence of gallstones has been reported to increase after gastrectomy. However, few studies have been conducted on the prevention of gallstone formation in patients who have undergone gastrectomy.

OBJECTIVE To evaluate the efficacy and safety of ursodeoxycholic acid (UDCA) in preventing gallstone formation after gastrectomy in patients with gastric cancer.

DESIGN, SETTING, AND PARTICIPANTS The PEGASUS-D study (Efficacy and Safety of DWJ1319 in the Prevention of Gallstone Formation after Gastrectomy in Patient with Gastric Cancer: A Multicenter, Randomized, Double-blind, Placebo-controlled Study) was a randomized, double-blind, placebo-controlled clinical trial conducted at 12 institutions in the Republic of Korea. Adults (aged ≥19 years) with a diagnosis of gastric cancer who underwent total, distal, or proximal gastrectomy were enrolled between May 26, 2015, and January 9, 2017; follow-up ended January 8, 2018. Efficacy was evaluated by both the full analysis set, based on the intention-to-treat principle, and the per-protocol set; full analysis set findings were interpreted as the main results.

INTERVENTIONS Eligible participants were randomly assigned to receive 300 mg of UDCA, 600 mg of UDCA, or placebo at a ratio of 1:1:1. Ursodeoxycholic acid and placebo were administered daily for 52 weeks.

MAIN OUTCOMES AND MEASURES Gallstone formation was assessed with abdominal ultrasonography every 3 months for 12 months. Randomization and allocation to trial groups were carried out by an interactive web-response system. The primary end point was the proportion of patients developing gallstones within 12 months after gastrectomy.

RESULTS A total of 521 patients (175 received 300 mg of UDCA, 178 received 600 mg of UDCA, and 168 received placebo) were randomized. The full analysis set included 465 patients (311 men; median age, 56.0 years [interquartile range, 48.0-64.0 years]), with 151 patients in the 300-mg group, 164 patients in the 600-mg group, and 150 patients in the placebo group. The proportion of patients developing gallstones within 12 months after gastrectomy was 8 of 151 (5.3%) in the 300-mg group, 7 of 164 (4.3%) in the 600-mg group, and 25 of 150 (16.7%) in the placebo group. Compared with the placebo group, odds ratios for gallstone formation were 0.27 (95% CI, 0.12-0.62; P = .002) in the 300-mg group and 0.20 (95% CI, 0.08-0.50; P < .001) in the 600-mg group. No significant adverse drug reactions were detected among the enrolled patients.

CONCLUSIONS AND RELEVANCE Administration of UDCA for 12 months significantly reduced the incidence of gallstones after gastrectomy for gastric cancer. These findings suggest that UDCA administration prevents gallstone formation after gastrectomy in patients with gastric cancer.

TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02490111.