Predictive Value of Nutritional and Inflammatory Indices for Postoperative Complications After Bariatric Surgery

Overview

Bariatric surgery is an effective treatment for severe obesity, but postoperative complications remain an important cause of morbidity. Several nutritional and inflammatory biomarkers derived from routine preoperative blood tests have been proposed as predictors of postoperative outcomes; however, their comparative value in bariatric surgery has not been fully established. This single-center retrospective cohort study will evaluate the ability of preoperative nutritional and inflammatory indices, including the Prognostic Nutritional Index (PNI), Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), Systemic Immune-Inflammation Index (SII), Systemic Inflammation Response Index (SIRI), and C-reactive Protein-to-Albumin Ratio (CAR), to predict 30-day postoperative complications following bariatric surgery. The study aims to identify the most clinically useful biomarker for preoperative risk stratification and optimization of perioperative care.

Bariatric surgery is the most effective treatment for severe obesity and obesity-related comorbidities. Despite advances in perioperative care, early postoperative complications continue to contribute to patient morbidity and healthcare utilization. Reliable preoperative risk stratification tools are therefore essential for identifying patients at increased risk and optimizing perioperative management. Nutritional status and systemic inflammation have emerged as important determinants of surgical outcomes. Several composite indices calculated from routinely available laboratory parameters, including albumin, C-reactive protein, leukocyte subsets, and platelet counts, have demonstrated prognostic value in different surgical populations. However, evidence regarding their comparative predictive performance in bariatric surgery remains limited. This single-center retrospective cohort study will include consecutive adult patients who underwent sleeve gastrectomy or gastric bypass procedures between 2023 and 2026. Preoperative nutritional and inflammatory indices (PNI, NLR, PLR, SII, SIRI, and CAR) will be calculated from the most recent preoperative laboratory values. The primary outcome is the occurrence of any Clavien-Dindo grade II or higher postoperative complication within 30 days after surgery. Secondary outcomes include the Comprehensive Complication Index (CCI), length of hospital stay, intensive care unit admission, and 30-day mortality. Multivariable regression analyses will be performed to determine the independent predictive value of each index after adjustment for relevant demographic and clinical variables. The findings of this study are expected to improve preoperative risk assessment and facilitate identification of patients who may benefit from targeted perioperative optimization strategies.