A novel noninvasive appendicitis score with a urine biomarker.

Purpose: The aim of our study was to develop an appendicitis score incorporating a urine biomarker, Leucine rich alpha-2-glycoprotein (LRG), for evaluation of children with abdominal pain.

Methods: From January to August 2017 we prospectively enrolled children aged 4-16 years old admitted for suspected appendicitis. Urine samples for LRG analysis were obtained preoperatively and quantified by enzyme-linked immunosorbent assay (ELISA) after correction for patient hydration status. The diagnosis of appendicitis was based on operative findings and histology. Logistic regression was used to identify prospective predictors.

Results: A total of 148 patients were recruited, of which 42(28.4%) were confirmed appendicitis. Our Appendicitis Urinary Biomarker (AuB) model incorporated urine LRG with 3 clinical predictors: 'constant pain', 'right iliac fossa tenderness', 'pain on percussion'. Area under the ROC curve for AuB was 0.82 versus 0.78 for the Pediatric Appendicitis Score (PAS) on the same cohort of patients. A model-calculated risk score of <0.15 is interpreted as low risk of appendicitis. Sensitivity for the AuB at this cutoff was 97.6%, specificity 37.7%, negative predictive value 97.6%, positive predictive value 38.3%, and negative likelihood ratio 0.06.

Conclusion: The noninvasive AuB score appears promising as a diagnostic tool for excluding appendicitis in children without the need for blood sampling.

Type Of Study: Study of diagnostic test.

Level Of Evidence: Level III.