Emergency department evaluation of immature granulocytes for complicated acute appendicitis: a retrospective cohort study.

BACKGROUND

Preoperative identification of complicated acute appendicitis (CAA) is important for reducing morbidity. We assessed the diagnostic value of immature granulocyte (IG) count and percentage (IG%) for predicting CAA and histopathologically confirmed perforation in adults presenting to the emergency department.

METHODS

We retrospectively reviewed consecutive adults (≥18 years) with histopathologically confirmed appendicitis admitted to a tertiary care center between January 1, 2025 and January 1, 2026. Cases were classified as CAA or non-complicated acute appendicitis (NAA). Perforation was analyzed as a separate secondary endpoint. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis, the Youden index, and multivariable logistic regression.

RESULTS

A total of 891 patients were included (58.6% male; median age, 35 years [IQR 25-47]); 466 (52.3%) had CAA and 105 (11.8%) had perforation. For discrimination of CAA, the highest area under the curve (AUC) was observed for the neutrophil-to-lymphocyte ratio (NLR) (0.547; 95% confidence interval [CI]: 0.508-0.586), whereas the AUC for IG% was 0.519 (95% CI: 0.479-0.556). Among patients with perforation, lymphocyte counts were lower (p=0.032) and NLR values were higher (p=0.018). Although IG% was numerically higher and demonstrated a small-to-moderate effect size (Cohen's d=0.257), the difference did not reach statistical significance (p=0.116). In multivariable analysis, IG% did not reach independent statistical significance for perforation (adjusted odds ratio [aOR]=1.66; 95% CI: 0.99-2.76; p=0.053), although the point estimate suggested a possible positive association.

CONCLUSION

IG count and IG% did not provide clinically meaningful discrimination between CAA and NAA. The non-significant association observed for IG% in the multivariable perforation model should be considered hypothesis-generating rather than confirmatory. These findings challenge the high diagnostic performance reported in previous smaller studies and do not support the use of IG count or IG% as standalone preoperative biomarkers in adult acute appendicitis.