C-reactive protein and white blood cell count do not improve clinical decision-making in acute appendicitis

Acute appendicitis (AA) remains a diagnostic challenge as indicated by the high rate of unnecessary surgery. Blood samples, primarily C-reactive protein (CRP) and leucocyte counts, are used as a diagnostic supplement despite their relatively low sensitivities and specificities. However, their influence on diagnostic decision-making has not previously been investigated. The aim of the present study was to investigate if the results of CRP and leucocytes had any positive or negative influence on the decision-making of surgeons handling patients with suspected AA.

This was a prospective, observational cohort study including patients (≥ 15 years of age) admitted on suspicion of AA. The surgeons were instructed to perform their physical examination and to register whether they found the patient more or less than 50% likely to have AA. Thereafter, the surgeons had to assess the blood results and re-evaluate their diagnosis. The surgeon's diagnosis before and after was compared with the final diagnosis defined by surgical findings or follow-up. The gold standard was any degree of appendicitis on histology.

A total of 226 patients were included of whom 91 (40.3%) had appendicitis on histology. The surgeons changed their diagnosis in nine cases after assessing blood samples. The changes in the proportion of correct diagnoses, sensitivity, specificity and predictive values after assessing blood samples were not significant.

The results of CRP and leucocyte counts did not influence clinical decision-making.

Financial support was obtained from the Danish Council for Independent Research (Ref. no. 12-132020).

Clinicaltrials.gov: NCT02304653.