DetermIning Surgical Complications in the OVERweight (DISCOVER) was our second study and saw the expansion of STARSurg to include medical students and junior doctors from the Republic of Ireland. The study had two main aims, firstly, to determine whether obesity was associated with an excess risk of major post-operative complications, and secondly to establish compliance to National Institute for Health and Care Excellence (NICE) guidelines in relation to early identification of obese patients, NICE recommending that all patients undergo calculation of body-mass index (BMI) upon admission to hospital.

From October to December 2014 over 1200 medical students and junior doctors contributed data for 7965 patients undergoing open or laparoscopic, elective or emergency, gastrointestinal, bariatric or hepatobiliary surgery from over 140 hospitals. The primary end point of the study was the overall 30-day major complication rate (Clavien-Dindo grade III–V complications). 

Of 7965 patients, 2545 (32·0%) were of normal weight, 2673 (33·6%) were overweight and 2747 (34·4%) were obese. The 30‐day major complication rate was 11·4%. 

In adjusted models, an association was seen between BMI and major complications for patients with malignancy (overweight: OR 1·59, 95% CI 1·12 to 2·29, p = 0·008; obese: OR 1·91, 95% CI 1·31 to 2·83, p = 0·002; compared to normal weight). However, this was not seen in benign disease (overweight: OR 0·89, 95% CI 0·71 to 1·12, p = 0·329; obese: OR 0·84, 95% CI 0·66 to 1·06, p = 0·147).