Unveiling the intrinsic role of malnutrition in patients with Crohn's disease undergoing major surgery using entropy balancing weighting analysis

The negative role of malnutrition in patients with Crohn's disease is known; however, many coexisting disease-related factors could cause misinterpretation of the real culprit. This study aimed to describe the role of malnutrition using a novel methodology, entropy balancing. This was a retrospective analysis of consecutive patients undergoing elective major surgery for Crohn's disease, preoperatively screened following the European Society for Clinical Nutrition guidelines. Two-step entropy balancing was applied to the group of malnourished patients to obtain an equal cohort having a null or low risk of malnutrition. The first reweighting homogenised the cohorts for non-modifiable confounding factors. The second reweighting matched the two groups for modifiable nutritional factors, assuming successful treatment of malnutrition. The entropy balancing was evaluated using the d-value. Postoperative results are reported as mean difference or OR, with a 95 % CI. Of the 183 patients, 69 (37·7 %) were at moderate/high risk for malnutrition. The malnourished patients had lower BMI (d = 1·000), Hb (d = 0·715), serum albumin (d = 0·981), a higher lymphocyte count (d = 0·124), Charlson Comorbidity Index (d = 0·257), American Society of Anaesthesiologists (d = 0·327) and Harvey-Bradshaw scores (d = 0·696). Protective loop ileostomy was more frequently performed (d = 0·648) in the malnourished group. After the first reweighting, malnourished patients experienced a prolonged length of stay (mean difference = 1·9; 0·11, 3·71, days), higher overall complication rate (OR 4·42; 1·39, 13·97) and higher comprehensive complication index score (mean difference = 8·9; 2·2 15·7). After the second reweighting, the postoperative course of the two groups was comparable. Entropy balancing showed the independent role of preoperative malnutrition and the possible advantages obtainable from a pre-habilitation programme in Crohn's disease patients awaiting surgery.