Diagnostic accuracy of inflammatory markers in patients operated on for suspected acute appendicitis: a receiver operating characteristic curve analysis.

OBJECTIVE

To analyse the diagnostic accuracy of inflammatory variables in patients operated on for suspected acute appendicitis.

DESIGN

Open prospective population based study.

SETTING

Teaching hospital, Norway.

INTERVENTIONS

Appendicectomy in 544 patients with clinically suspected acute appendicitis.

MAIN OUTCOME MEASURES

Diagnostic accuracy of inflammatory variables using receiver operating characteristic (ROC) curve analysis. Logistic regression model of inflammatory variables using results of ROC-analysis.

RESULTS

A small area under the ROC curve (AUC) (between 0.56 and 0.69) indicated less diagnostic accuracy. The best cut-off values were associated with low sensitivity and specificity, varying from 46% to 88%. Age, duration of history, and histological grade of inflammation significantly influenced the test results (AUC >0.5). The white cell count (WCC) and C-reactive protein (CRP) concentration were independent predictors of acute appendicitis with cut-off values of >12.3x10(9)/L and >0 mg/L, respectively, but AUC values of over 0.5 were observed only in patients between 13 and 40 years of age.

CONCLUSION

Inflammatory variables added information of limited value in the diagnosis of suspected acute appendicitis. The test results should be interpreted differently in different groups of patients.