Background: The aim of this study was to assess the diagnostic value of procalcitonin (PCT) in emergency department (ED) patients with suspected appendicitis. Methods: A prospective observational study was carried out inthe emergency department of a university hospital between July 2007 and June 2008. Adult patients who presented to the ED with clinically suspected appendicitis were enrolled. Each patient underwent serum PCT, C-reactive protein (CRP), and Alvarado score evaluation on admission. The results of these three measurements were analyzed in relation to the final diagnosis determined by histopathological findings or compatible computed tomography findings. Results: Of the 214 study patients, 113 (52.8 %) had a confirmed diagnosis of appendicitis and 58 had complicated appendicitis (phlegmon, perforation, or gangrene). For the diagnosis of appendicitis, the area under the receiving operating characteristic (ROC) curve is 0.74 for Alvarado score, 0.69 for PCT, and 0.61 for CRP. Overall, the Alvarado score has the best discriminative capability among the three tested markers. We adopted two cutoff point approaches to harness both ends of the diagnostic value of a biomarker. PCT levels were significantly higher in patients with complicated appendicitis. For diagnosis of complicated appendicitis, a cutoff value of 0.5 ng/mL had a sensitivity of 29 % and a specificity of 95 %,while a cutoff value of 0.05 ng/ml had a sensitivity of 85 % and a specificity of 30 % in diagnosing complicated appendicitis. For those with a PCT value in the gray zone, clinical findings may play a more important role. Conclusion: The study does not support the hypothesis that the PCT test may be useful for screening ED patients for appendicitis. However, determination of the PCT level may be useful for risk assessment of ED patients with suspected complicated appendicitis.
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