A Prospective Observational Study to Assess the Neutrophil-to-Lymphocyte Ratio (NLR) and C-reactive Protein-to-Albumin Ratio (CAR) in Predicting Morbidity and Mortality Among Patients Undergoing Emergency Abdominal Surgery

Background Emergency abdominal surgeries pose significant challenges, especially in the Indian population, due to comorbidities, delayed presentations, and limited resources. Accurately predicting morbidity and mortality is crucial for timely interventions and improved patient care. The neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein-to-albumin ratio (CAR) have shown potential as prognostic markers, balancing inflammation and nutritional status. Aim The study aims to evaluate the predictive efficacy of NLR and CAR with regard to postoperative morbidity and mortality in patients undergoing emergency abdominal surgery, thereby contributing to better risk stratification and management strategies. Patients and methods A prospective observational study was conducted in a tertiary teaching hospital in northern Karnataka from August 2022 to June 2024, involving 102 patients undergoing emergency abdominal surgeries. The sample size (71) was calculated using G*Power software, targeting a 95% power with a 5% significance level. The inclusion criterion was patients aged over 18 years undergoing emergency abdominal surgeries; those who were immunocompromised, on steroid therapy, having malignancies, undergoing radiotherapy, or having chronic liver diseases were excluded from the study. Patients coming into the surgical inpatient department (IPD) with an acute abdomen requiring emergency abdominal surgeries as an emergency were preoperatively assessed using complete blood count (CBC), CRP, and serum albumin tests. NLR and CAR were evaluated preoperatively and at 24 and 48 hours postoperatively. The outcome measures included surgical site infection rates, hospital stay duration, and outcome in the form of recovery or death. SPSS version 20 was used for statistical analyses. Results The study included 102 patients whose mean age was 43.7 ± 18.9 years; 74 of the participants (72.5%) were male. The most common procedures were exploratory laparotomy (64 patients; 62.7%) and appendicectomy (32 patients; 31.4%). A significant increase in CAR levels was observed on postoperative days 1 and 2 compared to baseline (p < 0.05). Preoperative NLR ≥ 8 was significantly associated with higher mortality (65% vs. 50%, p < 0.01). Preoperative albumin > 3.2 g/dL was associated with better outcomes (recovery in 54 patients; 65.9%) compared to < 3.2 g/dL (15 patients; 75% mortality). This study showed that NLR and CAR are valuable predictors of postoperative outcomes, with CAR indicating the risk for surgical site infections (SSI) and NLR predicting mortality. Conclusion The preoperative NLR had a significant association with mortality among the patients. Hence the NLR can be a good marker for the worst outcome and CAR during the postoperative period can be considered as a marker to detect the risk of SSI. NLR and CAR are simple, inexpensive tests readily available from routine blood investigations. The utility of NLR and CAR as valuable prognostic markers in the perioperative assessment of patients undergoing emergency abdominal surgery could enhance the prediction of patient outcomes and guide more effective management strategies to improve patient outcomes in high-risk emergency abdominal surgery.