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

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.

Inclusion criteria

Adults aged 18 years or older.

• Patients who underwent bariatric surgery (sleeve gastrectomy, Roux-en-Y gastric bypass, SADI, or SASI).
• Availability of complete preoperative laboratory data required for calculation of nutritional and inflammatory indices.
• Availability of postoperative follow-up data for assessment of 30-day complications.

Exclusion criteria

• Patients younger than 18 years.

• Missing key preoperative laboratory values required to calculate study indices.
• Incomplete medical records or unavailable 30-day postoperative outcome data.