Postoperative Complications and Mobilization Following Major Abdominal Surgery With Versus Without Fitness Tracker-based Feedback (EXPELLIARMUS): A Student-led Multicenter Randomized Controlled Clinical Trial of the CHIR-Net SIGMA Study Group.

Objective: To determine whether daily postoperative step goals and feedback through a fitness tracker (FT) reduce the rate of postoperative complications after surgery.

Background: Early and enhanced postoperative mobilization has been advocated to reduce postoperative complications, but it is unknown whether FT alone can reduce morbidity.

Methods: EXPELLIARMUS was performed at 11 University Hospitals across Germany by the student-led clinical trial network SIGMA. Patients undergoing major abdominal surgery were enrolled, equipped with an FT, and randomly assigned to the experimental (visible screen) or control intervention (blackened screen). The experimental group received daily step goals and feedback through the FT. The primary end point was postoperative morbidity within 30 days using the Comprehensive Complication Index (CCI). All trial visits were performed by medical students in the hospital with the opportunity to consult a surgeon-facilitator who also obtained informed consent. After discharge, medical students performed the 30-day postoperative visit through telephone and electronic questionnaires.

Results: A total of 347 patients were enrolled. Baseline characteristics were comparable between the 2 groups. The mean age of patients was 58 years, and 71% underwent surgery for malignant disease, with the most frequent indications being pancreatic, colorectal, and hepatobiliary malignancies. Roughly one-third of patients underwent laparoscopic surgery. No imputation for the primary end point was necessary as data completeness was 100%. There was no significant difference in the CCI between the 2 groups in the intention-to-treat analysis (mean±SD CCI experimental group: 23±24 vs. control: 22±22; 95% CI: -6.1, 3.7; P=0.628). All secondary outcomes, including quality of recovery, 6-minute walking test, length of hospital stay, and step count until postoperative day 7 were comparable between the 2 groups.

Conclusions: Daily step goals combined with FT-based feedback had no effect on postoperative morbidity. The EXPELLIARMUS shows that medical students can successfully conduct randomized controlled trials in surgery.