The value of biochemical markers in predicting a perforation in acute appendicitis

Abstract

Acute appendicitis is the most common surgical diagnosis of abdominal pain. Perforated appendicitis can result in increased morbidity and mortality. Identifying a perforation early can reduce the impact on the patient. Bilirubin, C-reactive protein (CRP) and white cell count (WCC) have been shown to indicate perforation in appendicitis. This study aimed to identify whether these biochemical markers can be used to identify if patients are suitable for either a conservative or surgical approach. A retrospective post hoc analysis of all appendicectomies over a 6-year period investigating the association between preoperative bilirubin, CRP, WCC, and neutrophil count and the histological findings of either the presence or lack of a perforation. One thousand two hundred seventy-one patients had appendicitis, 154 (12.12%) of which were perforated upon histological examination. All biochemical markers were significantly higher in perforation (P < 0.001). The greatest sum of sensitivity and specificity of CRP was at 34.6 mg/L (sensitivity 78.57%, specificity 63.01%), and for bilirubin was at 21.5 μmol/L (sensitivity 62.96%, specificity 88.31%). Combining CRP and bilirubin improved sensitivity and specificity, but this was reduced by further incorporating WCC and neutrophils. Logistic regression analysis identified CRP as the most sensitive marker of perforation (odds ratio (OR) = 1.064 (1.043-1.085) ) (P < 0.001), with bilirubin (OR = 1.005 (1.003-1.008) ) also significant (P < 0.001) for a 1-unit increase. Bilirubin and CRP are markers of perforation in appendicitis, but are not accurate enough to be diagnostic. In a patient with high clinical suspicion of acute appendicitis, a raised CRP and bilirubin suggests that a patient is not suitable for conservative treatment.