# Association of Sex, Age, and Inflammatory Cell Counts with Complicated Acute Appendicitis

## TL;DR

This study finds that male sex, age, and specific inflammatory cell counts are linked to complicated acute appendicitis, with immune profiles varying by sex and age.

## Contribution

The study identifies novel independent and interactive associations of sex, age, and immune cell counts with complicated acute appendicitis.

## Key findings

- CAA incidence is significantly higher in men compared to women.
- Male sex, age, and specific blood cell counts are independently associated with CAA.
- Neutrophil counts interact with both sex and age in influencing CAA risk.

## Abstract

Background/Objectives: Sex and age influence inflammatory responses, but researchers have not fully characterized their combined association with complicated acute appendicitis (CAA). This study assessed the independent and interactive associations of sex, age, and inflammatory cell counts with CAA. Methods: We conducted a retrospective observational study of 708 patients with histopathologically confirmed uncomplicated appendicitis (UAA) or CAA. We analyzed demographic and clinical data, including preoperative complete blood counts, stratified by sex. We used multivariable logistic regression models with interaction terms to evaluate associations and possible effect modification by sex and age. We explored the direction and magnitude of these interactions by estimating marginal predicted probabilities. Results: The incidence of CAA was significantly higher in men than in women. In men with CAA, complete blood count analysis showed elevated neutrophil and monocyte counts and reduced lymphocyte counts. Male sex (odds ratio (OR) 2.197, 95% confidence interval (CI) 1.610–2.999), continuous age (1.017, 1.002–1.033), lymphocyte count (0.656, 0.526–0.820), monocyte count (1.551, 1.036–2.321), and platelet count (1.004, 1.001–1.006) were independently associated with CAA. Interaction analysis revealed significant interactions between neutrophils and both sex and age (p < 0.05), while lymphocyte counts showed significant interaction with age but not with sex. Conclusions: This study provides new insight into complex sex- and age-related immune cell patterns in CAA and may inform future diagnostic and management strategies by highlighting immune profile variability.