Discriminatory capacity of serum total bilirubin between complicated and uncomplicated acute appendicitis in children: a systematic review and a diagnostic test accuracy meta-analysis

This study aimed to examine the ability of serum total bilirubin (STB) to discriminate between complicated and uncomplicated paediatric acute appendicitis (PAA). We conducted a systematic review of the literature that involved an extensive search in the main databases of medical bibliography (Medline, PubMed, Web of Science, OVID, Scopus, Cochrane Library). Two independent reviewers selected the relevant articles based on the previously defined inclusion and exclusion criteria. Methodological quality of the selected articles was assessed using the QUADAS2 index. Data extraction was performed by two independent reviewers. A synthesis of the results, a standardization of the metrics and a random-effect meta-analysis were performed. Between-study heterogeneity was assessed in subgroup analysis by study design. In addition, a diagnostic test accuracy (DTA) meta-analysis was performed. This review included 8 studies with data from 3634 participants aged between 0 and 18 years (2230 with uncomplicated PAA and 1404 with complicated PAA). The random-effects meta-analysis showed significantly higher mean STB in the complicated PAA group than in the uncomplicated PAA group (difference = 0.27; 95% CI 0.06–0.48) and high heterogeneity (I² = 96%). In subgroup analyses by study design, the difference remained significant in prospective studies. The DTA meta-analysis resulted in an AUC of 0.83 (95% CI 0.79–0.86) and pooled sensitivity and specificity of 68.53% (95% CI 48.35%–83.51%) and 81.12% (95% CI 67.76%–89.78%), respectively. Mean values of STB are higher in children with complicated than uncomplicated acute appendicitis, and the diagnostic yield of STB seems to be high. Due to the high heterogeneity between studies, these results must be interpreted with caution.