Conceptual Clinical Variables Enhancing the Alvarado Score in Pediatric Appendicitis: Lessons for Artificial Intelligence Models

Background: Timely and accurate diagnosis of pediatric appendicitis remains challenging because of variable clinical presentations and limitations of existing scoring systems. Although the Alvarado score is widely used, its diagnostic performance in children is suboptimal, and reliance on imaging increases resource utilization and radiation exposure. Identification of objective, biologically meaningful predictors may improve early diagnosis and inform future artificial intelligence (AI)–based decision-support models. Methods: This retrospective study included children aged 2–18 years evaluated for suspected appendicitis between January 2014 and June 2024. Clinical characteristics, laboratory data, urinalysis results, imaging findings, operative notes, and histopathological reports were reviewed. Diagnostic performance of individual variables and the Alvarado score was assessed using sensitivity, specificity, predictive values, diagnostic odds ratios, and receiver operating characteristic analysis. A composite diagnostic framework based on seven clinical and laboratory factors was evaluated and compared with the Alvarado score alone. Results: A total of 375 patients were included, of whom 275 (73.3%) were diagnosed with appendicitis. Appendicitis was more prevalent in males and in children aged ≥6 years, with the highest incidence in preadolescence. The mean Alvarado score was significantly higher in the appendicitis group than in the non-appendicitis group (8 ± 2 vs 5 ± 2, p < 0.001). At a cut-off score of ≥7, the Alvarado score demonstrated a sensitivity of 77.1%, specificity of 71.0%, and an AUC of 74.05%. Seven factors—sex, age group, location of abdominal pain, white blood cell count, neutrophil percentage, urine ketone level ≥3+, and leukocyte esterase level—were significantly associated with appendicitis. The seven diagnostic conceptual factors achieved superior diagnostic performance (AUC 86.77%, 95% CI 82.56–90.96) compared with the Alvarado score alone. Urinary ketone levels ≥3+ showed a significant positive association with appendicitis, whereas leukocyte esterase demonstrated an inverse association. Conclusions: Integration of seven objective clinical and laboratory factors improves early diagnostic accuracy for pediatric appendicitis beyond the Alvarado score alone and supports more targeted use of ultrasonography in equivocal cases. Urinary ketones are a particularly useful adjunctive marker due to their physiological relevance and persistence after fluid resuscitation. Establishing structured, clinically meaningful data pipelines is essential for future development of reliable and explainable AI-assisted diagnostic tools.