Preoperative Anaemia and Early Postoperative Morbidity According to the Clavien-Dindo Classification After Major Gastrointestinal Surgery: a Prospective Observational Cohort Study

This prospective observational cohort study evaluated the association between preoperative anaemia and early postoperative morbidity in adults undergoing major gastrointestinal surgery at the University Hospital of Ioannina, Greece. Consecutive patients undergoing elective or urgent open or laparoscopic gastrointestinal surgery were enrolled. Preoperative anaemia was defined as haemoglobin <13.0 g/dL in men and <12.0 g/dL in non-pregnant women. Patients were followed from surgery until hospital discharge or postoperative day 8, whichever occurred first. The primary outcome was any postoperative complication during this period. Secondary outcomes were major postoperative complications, defined as Clavien-Dindo grade III or higher, and discharge beyond the expected recovery period. The study also evaluated whether the association between preoperative anaemia and postoperative morbidity persisted after accounting for comorbidity, urgency of surgery, and surgical risk.