Single and combined diagnostic value of clinical features and laboratory tests in acute appendicitis

The objective was to evaluate the diagnostic accuracy of clinical features and laboratory test results in detecting acute appendicitis.

Clinical features and laboratory test results were prospectively recorded in a consecutive series of 1,101 patients presenting with abdominal pain at the emergency department (ED) in six hospitals. Likelihood ratios (LRs) and the areas under the receiver operating characteristic curve (AUC) were calculated for the individual features. Variants of clinical presentation, based on different combinations of clinical features, were investigated and the accuracies of combinations of clinical features were evaluated.

The discriminative power (AUC) of the individual features in patients with suspected appendicitis ranged from 0.50 to 0.65. For five of the 23 predictor sets, the accuracy for appendicitis was more than 85%. This accuracy was only found in male patients. The relative frequency of these predictor sets ranged from 2% to 13% of patients with suspected appendicitis. A combination of the clinical features migration of pain to the right lower quadrant (RLQ), and direct tenderness in the RLQ, was present in only 28% (120/422) of clinically suspected patients, of whom no more than 85 patients had appendicitis (71%). A "classical" presentation (combination of migration of pain to the RLQ, tenderness in the RLQ, and rigidity) occurred in only 6% (25/422) of patients with suspected appendicitis and yielded an accuracy of 100% in males but only 46% in females.

The discriminative power (AUC) of individual clinical features and laboratory test results for appendicitis was weak in patients with suspected appendicitis. Combinations of clinical features and laboratory tests with high diagnostic accuracy are relatively infrequent in patients with suspected appendicitis.