Repeated scoring with the adult appendicitis score improves the sensitivity and the specificity of appendicitis diagnosis in patients with early equivocal signs of appendicitis: a secondary analysis

Abstract

Abstract Background The use of computed tomography at the early stage of acute appendicitis can lead to overdiagnosis and predispose patients unnecessarily to ionising radiation. Adult Appendicitis Score (AAS) can be used to select patients for imaging. Observation and re-scoring in the DIAMOND trial reduced the need for imaging. In this study, we wanted to determine if the AAS change (ΔAAS) can be used as a diagnostic tool to select patients for imaging even more precisely. Methods Eighty-eight patients with early equivocal appendicitis entered the observation arm in the DIAMOND trial. The data of these patients were reanalysed, and ΔAAS during the observation was calculated. The baseline AAS, final AAS, and the CRP change (ΔCRP) were selected as reference standards. Results Eighty-three patients with complete data were analysed. The AUROC values: ΔAAS 0.932 (95%CI 0.868–0.996), baseline AAS 0.629 (95%CI 0.498–0.760), final AAS 0.936 (95%CI 0.886–0.987), and ΔCRP 0.796 (95%CI 0.696–0.897). From receiver operating characteristic curves, we identified the limits for low (ΔAAS ≤ -2), intermediate (ΔAAS − 1 − 0), and high (ΔAAS ≥ 1) probability of appendicitis. The negative predictive value of the low probability group and the positive predictive value of the high probability group for acute appendicitis were 97% and 94%, respectively. Conclusions Patients with equivocal signs of appendicitis could benefit from short observation and calculation of ΔAAS to reduce overdiagnosis and exposure to excessive imaging. Trial registration The DIAMOND trial was originally registered in ClinicalTrials.gov (NCT02742402) on April 7th, 2016 and approved by the institutional review board and the ethical committee of Helsinki University Hospital (reference number 27/13/03/02/2016).