Background: Pediatric acute appendicitis (PAA) continues to be a diagnostic challenge today. The diagnostic performance of classical indices is only moderate, especially in pediatric population. This study aimed to define a clinical, radiological and analytical index for the diagnosis of PAA. Materials and methods: This prospective study included 151 patients divided into two groups: (1) 53 patients with non-surgical abdominal pain (NSAP) and (2) 98 patients with a confirmed PAA. Sociodemographic and clinical characteristics were compared between groups using the Mann–Whitney U test and the Fisher exact test. To identify the predictors of PAA, we performed a multivariable logistic regression using a forward stepwise analysis and we assigned multiples of integer values to the selected variables. The diagnostic performance of the index was assessed by calculating the area under the receiver operating characteristic curve. Intra-cohort calibration was assessed with the Hosmer–Lemeshow test. Results: We developed the BIDIAP index (BIomarkers for the DIagnosis of Appendicitis in Pediatrics), which included three variables that independently predicted higher odds of PAA: appendiceal caliber (≥ 6.9 mm), systemic immune-inflammation index (≥ 890) and peritoneal irritation, which scored 4, 3 and 2 points, respectively. Mean (SD) score of the participants was 2.38 (2.06) in group 1 and 7.89 (1.50) in group 2. The area under the ROC was 0.97 (95% CI 0.95–0.99). The cut-off point was established at 4 points, resulting in a sensitivity of 98.98% and a specificity of 77.78%. Conclusions: The BIDIAP index has an exceptional diagnostic performance in PAA. The importance of these results lies in its novelty and in the simplicity of the index. Although external validation will be necessary, initial results look promising.

Background: Serum interleukin-6 (IL-6) has a moderate diagnostic performance in pediatric acute appendicitis (PAA). The evidence regarding its capacity to discern between complicated and uncomplicated PAA is scarce. Methods: We designed a prospective observational study to validate serum IL-6 as a marker for diagnostic classification between complicated and uncomplicated PAA. This study included 205 patients divided into three groups: (1) patients who underwent major outpatient surgery (n = 57); (2) patients with non-surgical abdominal pain (NSAP) in whom the diagnosis of PAA was excluded (n = 53), and (3) patients with a confirmed diagnosis of PAA (n = 95). The PAA patients were further classified as uncomplicated or complicated PAA. IL-6 concentration was determined in all patients at diagnosis. Comparative statistical analysis was performed using the Mann-Whitney U test, the Fisher exact test and the Kruskall Wallis test. The area under the receiver operating characteristic curves (AUC) were calculated. Results: Median (interquartile range, IQR) serum IL-6 values were 2 pg/mL (2.0–3.4) in group 1, 3.9 pg/mL (2.4–11.9) in group 2, and 23.9 pg/mL (11.1–61.0) in group 3 (P < 0.001). Among the participants in group 3, those with uncomplicated PAA had median (IQR) serum IL-6 values of 17.2 pg/mL (8.5–36.8), and those with complicated PAA had 60.25 pg/mL (27.1–169) serum IL-6 (P < 0.001). At the cut-off point of 19.55 pg/mL, the AUC for the discrimination between patients in group 2 vs. 3 was 0.83 [95% confidence interval (CI) 0.76–0.90], with a sensitivity of 61.3% and a specificity of 86.8. The AUC for the discrimination between patients with uncomplicated and complicated PAA was 0.77 (95% CI 0.68–0.86) and the cut-off point was 25.90 pg/mL, with a sensitivity and specificity of 84.6% and 65.6%, respectively. Conclusions: Serum IL-6 has a good performance in discerning between complicated and uncomplicated PAA. A score including clinical and radiological variables may increase the diagnostic performance of this molecule.

Background: The aim of this study was to analyze the diagnostic performance of total platelet count (PC), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) in pediatric acute appendicitis (PAA). Methods: We conducted a systematic review of the literature in the main databases of medical bibliography. Two independent reviewers selected the articles and extracted relevant data. Methodological quality was assessed using the QUADAS2 index. A synthesis of the results, a standardization of the metrics, and four random effect meta-analyses were performed. Results: Thirteen studies including data from 4,373 participants (2,767 patients with confirmed diagnosis of PAA and 1,606 controls) were included. Five studies compared PC, and the meta-analysis including three of them showed a non-significant mean difference of −34.47 platelets/1 × 10⁹/L (95% confidence interval [CI], −88.10 to 19.16). Seven publications compared PLR and the meta-analysis of those studies showed significant mean differences between patients with PAA and controls (dif: 49.84; 95% CI, 25.82–73.85) as well as between patients with complicated and uncomplicated PAA (dif: 49.42; 95% CI, 25.47–73.37). Four studies compared MLR and the meta-analysis including all of them showed a non-significant mean difference of −1.30 (95% CI, −3.52 to 0.92). Conclusions: Although existing evidence is heterogeneous and limited, PLR appears to be a promising molecule for the diagnosis of PAA and for the discrimination between complicated and uncomplicated PAA. Our results do not support the use of PC or MLR as biomarkers in PAA.

The aim of this study was to analyze the diagnostic performance of Leucine-Rich Alpha-2-Glycoprotein (LRG1) in pediatric acute appendicitis (PAA). We conducted a systematic review of the literature in the main databases of medical bibliography. Two independent reviewers selected the articles and extracted relevant data. Methodological quality was assessed using the QUADAS2 index. A synthesis of the results, standardization of the metrics and 4 random-effect meta-analyses were performed. Eight studies with data from 712 participants (305 patients with confirmed diagnosis of PAA and 407 controls) were included in this review. The random-effect meta-analysis of serum LRG1 (PAA vs control) resulted in a significant mean difference (95% CI) of 46.76 μg/mL (29.26–64.26). The random-effect meta-analysis for unadjusted urinary LRG1 (PAA vs control) resulted in a significant mean difference (95% CI) of 0.61 μg/mL (0.30–0.93). The random-effect meta-analysis (PAA vs control) for urinary LRG1 adjusted for urinary creatinine resulted in a significant mean difference (95% CI) of 0.89 g/mol (0.11–1.66). Conlusion: Urinary LRG1 emerges as a potential non-invasive biomarker for the diagnosis of PAA. On the other hand, due to the high between-study heterogeneity, the results on serum LRG1 should be interpreted with caution. The only study that analyzed salivary LRG1 showed promising results. Further prospective studies are needed to confirm these findings. What is Known:• Pediatric acute appendicitis continues to be a pathology with a high rate of diagnostic error.• Invasive tests, although useful, are a source of stress for patients and their parents. What is New:• LRG1 emerges as a promising urinary and salivary biomarker for the noninvasive diagnosis of pediatric acute appendicitis.