Laboratory biomarkers in acute appendicitis: a retrospective cohort analysis

Abstract

Introduction:
Acute appendicitis is one of the most common pathologies in abdominal surgery, where early severity stratification is crucial for preventing complications. Inflammatory biomarkers and their derived ratios—CRP(mg/L)/albumin(g/L) (CAR), fibrinogen(mg/L)/albumin(g/L) (FAR), and neutrophil-to-lymphocyte ratio (NLR)—are considered cost-effective and accessible tools for improving diagnostic accuracy and clinical triage.

Materials and Methods:
A retrospective analysis was conducted on patients with acute appendicitis operated between 1.10.2024 and 1.10.2025 at the Second Clinic of Surgery, University Multiprofile Hospital for Active Treatment “N. I. Pirogov.” Patients with reactive appendicitis or incomplete laboratory data were excluded. Demographic characteristics, surgical approaches, intraoperative severity, CRP, fibrinogen, WBC, bilirubin levels, and the calculated CAR, FAR, and NLR ratios were evaluated. ROC curves, AUC values, Youden thresholds, and Pearson and Spearman correlation indexes were applied for statistical analysis.

Results:
A total of 73 patients were included in the study (57.5% operated laparoscopically, with a conversion rate of 12.3%). Gangrenous perforated appendicitis was identified in 37% of cases. CAR (AUC = 0.75), NLR (AUC = 0.74), and CRP (AUC = 0.74) demonstrated the highest diagnostic accuracy, followed by FAR (AUC = 0.70) and WBC (AUC = 0.69). The established thresholds for preoperative prediction of complicated appendicitis—CAR ≥ 2.28, NLR ≥ 7.21, FAR ≥ 0.09—were consistent with international reference ranges. The strongest correlations with disease severity were observed for CAR (ρ = 0.53), CRP (ρ = 0.51), and FAR (ρ = 0.49). Sex-specific differences were noted, with stronger correlations in female patients, as well as in those undergoing open or converted surgery. Higher biomarker values were associated with prolonged hospital stay.

Conclusions:
CAR, NLR, and FAR demonstrate significant diagnostic and prognostic value in assessing the severity of acute appendicitis. The identified thresholds are clinically applicable and support early identification of complicated forms. Routine usage of these biomarkers and their derived ratios may enhance triage accuracy, prognostication, and operative planning.