Diagnostic accuracy of doctors at the emergency department and radiologists in differentiating between complicated and uncomplicated acute appendicitis

Purpose: To determine the accuracy of final judgements of doctors at the emergency department (ED) and radiologists to differentiate between complicated and uncomplicated acute appendicitis, because these have different treatment options. Methods: This prospective, multicenter study included adult patients with imaging-confirmed acute appendicitis, operated with intention to appendectomy. Both doctors at ED and radiologists assessed appendicitis severity as a final judgement of “uncomplicated” or “complicated” appendicitis. Doctors at ED integrated clinical, laboratory, and imaging findings. Radiologists relied solely on imaging findings. Outcomes were accuracy of these judgements for diagnosis of complicated appendicitis compared to the reference standard by an adjudication committee. Results: After imaging, 1070 patients with confirmed acute appendicitis were included. Doctors at ED accurately labelled 656 of 701 (93.6%) patients with true uncomplicated appendicitis as uncomplicated, and 163 of 369 (44.2%) patients with true complicated appendicitis were labelled as complicated. Sensitivity, specificity, and positive and negative predictive values (PPV and NPV) for complicated appendicitis were 44.2%, 93.6%, and 78.4% and 76.1%, respectively. Comparable accuracy was found for the radiologist’s assessment in 941 patients, with true positive rates of 92.2% (581 of 630 patients) for uncomplicated appendicitis and 46.6% (145 of 311 patients) for complicated appendicitis. Conclusion: More than half of all patients with true complicated appendicitis is incorrectly classified as uncomplicated appendicitis according to the judgements of doctors at ED, integrating clinical, laboratory, and imaging results, and of radiologists assessing diagnostic imaging. These judgements are thereby not sufficiently reliable in ruling out complicated appendicitis.