Is C-reactive protein a reliable test for suspected appendicitis in extremely obese children?

Abstract

The diagnosis of acute appendicitis by physical examination can sometimes be difficult in extremely obese children. C-reactive protein (CRP) is commonly used to support the clinical diagnosis of appendicitis. However, obesity has been widely recognized as a chronic inflammatory condition and associated with elevated inflammatory indicators including CRP. The aim of this study was to examine the association between obesity and CRP levels in extremely obese children presenting with suspected appendicitis. The hospital records of 947 consecutive patients, who underwent appendectomy for acute appendicitis between 2002 and 2008 were retrospectively analyzed. 164 children (17.3%) were extremely obese. Extreme obesity was defined, as greater than two standard deviations above the standardized mean weight for age. The diagnostic value of CRP level was compared between extremely obese and non-obese children. The incidence of histologically normal appendix was significantly higher in extremely obese children [42 out of 164 (25.6%)] compared to non-obese children [85 out of 783 (10.8%) (P < 0.001)]. The mean CRP levels were significantly higher in extremely obese children with histologically normal appendix compared to non-obese children with normal appendix (P < 0.001). The specificity and the positive predictive value were significantly lower in the extremely obese children group than in the non-obese group (P < 0.001). CRP is not a reliable marker of inflammation in extremely obese children presenting with suspected appendicitis. Our data highlight the importance of obesity when interpreting the significance of an elevated CRP level in children with suspected diagnosis of appendicitis.