Introduction White cell count (WCC) and C-reactive protein (CRP) use in the diagnosis of acute appendicitis (AA) lacks sufficient sensitivity and specificity. The aim of this study was to assess the diagnostic accuracy of admission and serial plasma Complement proteins C3, C4, iC3b and TCC in AA.
Method A prospective observational study was undertaken between February 2012 and December 2013. Patients aged ≥18 years presenting with right iliac fossa pain with suspected AA were recruited. AA was defined histologically in operatively managed patients or on CT in conservatively managed cases. Plasma C3, C4, iC3b and TCC were measured on admission and at 4 and 8 h. The change (∆) in biomarker over 4 and 8 h was calculated by subtracting the concentration at admission from that at each time point to give ∆4and ∆8, respectively. Admission and ∆ values were compared in AA and all other conditions (non-AA) and the diagnostic efficacy was assessed using Receiver Operating Characteristic (ROC) curves.
Results 74 patients were recruited to the study, 26 participants were male (35%) with a median age of 33 years (range 18–84). Blood samples were obtained at 4 h and 8 h after admission in 43 and 28 patients, respectively. 31 patients underwent appendicectomy. AA was diagnosed in 22 cases (one case being diagnosed by CT and treated conservatively). Isolated admission C3, C4, iC3b and TCC did not discriminate between AA and non-AA. TCC∆4was diagnostic with a ROC Area Under Curve (AUC) of 0.84 (95% C. I 0.69–0.99). Admission WCC, Absoulte Neutrophil Count (ANC) and CRP demonstrated ROC AUCs of 0.75 (0.62–0.88), 0.76 (0.63–0.89) and 0.78 (0.67–0.88), respectively.
Conclusion TCC∆4 demonstrates good diagnostic accuracy in AA superior to admission conventional biomarkers WCC, ANC and CRP. TCC∆4could be used as a four hourly blood test in the Emergency Department to stratify patient risk for admission or further investigation. Further validation in a prospective observational study is required.
Disclosure of interest None Declared.