Serum interleukin-6 measurement in the diagnosis of acute appendicitis.

Background:  Many attempts have been made to determine ways of decreasing the negative laparotomy rate after a clinical diagnosis of acute appendicitis. The aim of the present study was to determine the effectiveness of serum interleukin-6 (IL-6) concentration in the diagnosis of appendicitis, and in the prevention of non-therapeutic laparotomy in patients with right iliac fossa pain. Methods:  Serum IL-6 concentrations were measured at admission in 77 consecutive patients who were operated on for the treatment of acute appendicitis. The final diagnosis was established by histopathological examination. The sensitivity, specificity and accuracy of IL-6 concentrations in the diagnosis of appendicitis were calculated. Results:  The negative laparotomy rate was 17% (13/77) in this series. The IL-6 level was elevated in seven of 13 patients (54%; false positive) with a normal appendix. The IL-6 level was normal in 10/64 patients (16%; false negative) with acute appendicitis. The IL-6 level was highly elevated in all patients with perforated appendicitis. The sensitivity, specificity, accuracy, and positive and negative predictive values were calculated as 84, 46, 78, and 89 and 38%, respectively. Conclusions:  Unacceptably high false negative and positive rates decrease the accuracy of the serum IL-6 test for appendicitis. Serum IL-6 measurement is not of benefit in increasing the accuracy of the diagnosis of appendicitis. Serum IL-6 results are not useful for preventing negative laparotomies in the majority of patients with right iliac fossa pain.