# The Role of Emerging Immune-Inflammatory Indexes in the Preoperative Differentiation of Complicated and Uncomplicated Acute Appendicitis: A Single-Center Retrospective Analysis

## TL;DR

This study shows that immune-inflammation indexes can help doctors tell the difference between simple and severe cases of appendicitis before surgery, improving patient care and reducing costs.

## Contribution

The study introduces and evaluates six immune-inflammation indexes as preoperative tools for differentiating complicated from uncomplicated acute appendicitis.

## Key findings

- Six immune-inflammation indices were significantly higher in complicated appendicitis cases.
- NLR and MLR were independent risk factors for complicated appendicitis.
- PIV predicted longer hospital stays and higher costs in complicated cases.

## Abstract

Background/Objectives: Acute appendicitis (AA) is among the most common surgical emergencies. Differentiating between complicated (CAA) and uncomplicated (UAA) forms is essential for selecting the appropriate management—operative or non-operative—and for optimizing patient prioritization and outcomes. This study aimed to evaluate the diagnostic performance of emerging inflammatory indices in distinguishing these forms of AA. Methods: A total of 514 adult patients with surgically confirmed AA were retrospectively analyzed. Six immune-inflammatory indices—neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and pan-immune-inflammation value (PIV)—were calculated and compared with intraoperative and histopathological findings. Postoperative outcomes, including length of hospital stay (LOS) and hospitalization costs, were also evaluated. Results: All six indices were significantly higher in intraoperatively identified complicated cases (p < 0.0001). In histopathological analysis, five indices (NLR, MLR, SII, SIRI, and PIV) remained significantly elevated in patients with wall necrosis or perforation (p = 0.000–0.019), while PLR did not reach statistical significance. The indices showed fair diagnostic accuracy (AUC = 0.664–0.719, p < 0.0001). NLR and MLR were independent risk factors for CAA (p = 0.006 and p = 0.016), and MLR was also independently associated with complicated histopathological findings (p = 0.036). PIV independently predicted both increased LOS and higher hospitalization costs (p = 0.001 for each). Conclusions: These easily calculable inflammatory markers can serve as useful adjuncts for preoperative stratification of AA, supporting timely decision-making and contributing to more cost-effective emergency surgical care.