Evaluation of copeptin as a marker for the diagnosis of acute appendicitis in children.

Copeptin has shown to correlate with acute appendicitis (AA) in adults. Its usefulness in the diagnosis of paediatric patients with suspected AA is unknown. The purpose of this study is to analyse the role of copeptin in the diagnosis of AA in children and to compare its diagnostic utility with other biomarkers. A prospective, observational, analytical, single-centre study was conducted in a Paediatric Emergency Department (PED) between June 2023 and May 2024. We included patients under 16 years presenting at the PED with acute abdominal pain (AAP) and clinical suspicion of AA after initial medical assessment. Patients with abdominal pain > 7 days were excluded. AA was defined as having a clinical diagnosis confirmed by histopathological examination. The diagnostic performance of copeptin and other biomarkers was analysed using ROC curves. Cut-off points were established according to the Youden index, and their usefulness was compared by sensitivity, specificity, and positive and negative predictive values (PPV, NPV). We report results from 246 patients [mean age 10.43 years (SD: 3.13)], of whom 60 (24.39%) had AA. The median copeptin level was 8.70 pmol/L (RIC 5.20-17.50), among patients with AA 15.20 pmol/L (RIC 7.40-31.70) and without AA 7.70 pmol/L (RIC 4.80-12.90) (p < 0.001). The area under the curve was 0.69 (95%CI: 0.61-0.77) for copeptin, 0.84 (95%CI: 0.79-0.89) for leukocytes, 0.84 (95%CI: 0.79-0.89) for neutrophils, and 0.70 (95%CI: 0.63-0.77) for C-reactive protein (CRP). The combination of biomarkers that showed the best diagnostic performance was leukocytes + CRP (sensitivity 96.67%, specificity 51.61%, PPV 39.19%, and NPV 97.96%).

conclusionCopeptin in association with other biomarkers (leukocytosis and neutrophilia) could be useful to rule out AA. WHAT IS KNOWN: • To date, none of the existing inflammatory biomarkers or their combinations have demonstrated consistent predictive value for the early diagnosis of acute appendicitis (AA) in paediatric population. • In recent years, studies in adults have examined various inflammatory molecules such as copeptin. Elevated copeptin levels have been associated with disease severity and mortality in different conditions. WHAT IS NEW: • Isolated copeptin values have limited utility as a biomarker for paediatric AA compared to existing biomarkers. • However, when combined with other biomarkers such as leukocytes or neutrophils, copeptin may help rule out AA.