The Role of Serum Biochemical Markers in Early Prediction of Complicated Appendicitis: A Single-Center Retrospective Analysis

Background: There is a lack of research on the use of biochemical markers to differentiate between uncomplicated appendicitis (UCA) and complicated appendicitis (CA) in adult patients. This study aims to identify biochemical markers associated with CA and to establish a predictive model. Methods: A retrospective analysis was conducted on the biochemical profiles of patients diagnosed with UCA and CA. Differences between the two groups were analyzed using SPSS. Univariate and multivariate binary logistic regression analyses were performed to identify independent risk factors. Diagnostic performance of the identified factors was visualized using R software. Results: A total of 265 patients were included, comprising 147 cases of UCA and 118 cases of CA. Multivariate logistic regression revealed that C-reactive protein (CRP) (OR = 6.725, 95% CI: 3.168–14.278, P  < 0.001), neutrophil-to-lymphocyte ratio (NLR) (OR = 2.238, 95% CI: 1.171–4.278, P  < 0.001), age (OR = 1.460, 95% CI: 1.197–1.782, P  = 0.015), and albumin (ALB) (OR = 0.799, 95% CI: 0.730–0.874, P  < 0.001) were independent risk factors for CA. ROC curve analysis showed that CRP had the highest area under the curve (AUC = 0.840), outperforming ALB (AUC = 0.839), age (AUC = 0.693), and NLR (AUC = 0.667), with a CRP cutoff value of 51.55 mg/L. The combined predictive model demonstrated superior diagnostic performance (AUC = 0.899), with a sensitivity of 90.0% and a specificity of 77.0%. Conclusions: In adults with acute appendicitis, CRP > 51.55 mg/L suggests a high likelihood of CA. A predictive model incorporating CRP, NLR, ALB, and age provides superior diagnostic accuracy and may assist in early identification of CA.