Abstract
<jats:p>INTRODUCTION: The epidemiology of adverse outcomes after abdominal surgery remains one of the key problems of modern surgery and anesthesiology-resuscitation because of an aging population and an increasing prevalence of comorbidity. OBJECTIVE: To describe the epidemiology of postoperative complications in high risk patients undergoing elective abdominal surgery and to compare their outcomes with the overall STOPRISK cohort. MATERIALS AND METHODS: A prospective, multicenter observational cohort study was conducted in 38 Russian centers and included 11 478 adults undergoing elective surgery on abdominal and pelvic organs; among them, 1367 patients (11.9 %) met guideline based criteria for high surgical risk. Postoperative complications within 30 days were recorded according to EPCO definitions and graded using the Clavien—Dindo classification, with detailed assessment of frequency, structure, severity and timing. RESULTS: In the high risk subgroup, at least one complication occurred in 14.2 % of patients and mortality was 1.8 %, approximately threefold higher than in the overall cohort (4.5 and 0.62 %, respectively). The most frequent complications were postoperative ileus (4.8 %), postoperative bleeding (2.6 %), wound infection and pneumonia (2.4 % each), anastomotic leakage (2.1 %), acute kidney injury and postoperative delirium (1.9 % each). Overall, 68.5 % of events were severe complications (Clavien—Dindo ≥ III), usually requiring intensive care and/or invasive interventions. Two thirds of all complications occurred within the first 5 postoperative days, which also concentrated most severe and fatal events, including circulatory arrest, severe respiratory and renal failure. CONCLUSIONS: High risk surgical patients, while representing a small proportion of the elective abdominal population, account for a disproportionally large share of severe complications and deaths. These findings support the implementation of targeted protocols for intensive monitoring, early diagnosis and prevention during the early postoperative window, as well as refinement of national perioperative risk stratification tools and resource planning.</jats:p>