Vladimir Raykov, Iryna Lytvynenko, Stoyan Sopotensky

Laboratory biomarkers in acute appendicitis: a retrospective cohort analysis

Introduction

Laboratory biomarkers in acute appendicitis: a retrospective cohort analysis. Acute appendicitis: CAR, NLR, FAR biomarkers aid severity stratification, diagnosis & prognosis. Identify complicated forms early, improving triage & surgical planning.

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.

Review

This retrospective cohort study investigates the diagnostic and prognostic value of various inflammatory biomarkers and their derived ratios (CAR, FAR, NLR, CRP, WBC) in assessing the severity of acute appendicitis. Addressing a critical need for early severity stratification in a common surgical pathology, the authors analyze a cohort of 73 patients to identify clinically applicable thresholds and correlations with disease severity and hospital stay. The findings suggest that CAR, NLR, and CRP demonstrate the highest diagnostic accuracy, with identified thresholds potentially aiding in the preoperative prediction of complicated appendicitis. The study provides valuable insights into the utility of these cost-effective and accessible tools for enhancing clinical triage and operative planning. A notable strength of this work lies in its focus on readily available and inexpensive laboratory markers, making the findings highly translatable to diverse clinical settings. The study meticulously calculates and evaluates derived ratios like CAR and FAR, which are increasingly recognized for their predictive power. The identification of specific thresholds (e.g., CAR ≥ 2.28, NLR ≥ 7.21) for complicated appendicitis provides actionable data for clinicians. Furthermore, the reporting of robust correlations with disease severity and prolonged hospital stay underscores the prognostic utility of these biomarkers. The authors also add valuable nuance by identifying sex-specific differences and variations based on surgical approach, suggesting more tailored diagnostic strategies. While the study presents compelling results, several limitations warrant consideration. Most critically, the specified timeline for patient recruitment ("operated between 1.10.2024 and 1.10.2025") indicates that the study period is in the future, which is a significant anomaly for a retrospective analysis and must be rectified. Assuming this is a typographical error and the study was indeed conducted retrospectively, other limitations include the single-center design and relatively small sample size (N=73), which may limit the generalizability and statistical power of the derived thresholds and correlations. Future research should prioritize prospective, multi-center studies with larger cohorts to validate these findings rigorously. Additionally, exploring the additive value of these biomarkers when combined with imaging modalities would further enhance their clinical utility in the diagnostic algorithm for acute appendicitis.

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