The Role of C-reactive Protein in Diagnosis of Acute Complicated Appendicitis: A Diagnostic Accuracy Study

Introduction: Acute appendicitis is one of the most common emergencies of general surgery. Contrary to simple appendicitis, the complicated cases are associated with higher morbidity and mortality. Except for pathology, no accurate diagnostic test has been found to identify complicated cases. Objective: Here in, we aim to evaluate the serum C-Reactive Protein (CRP) level in both acute simple and complicated appendicitis. Methods: In this diagnostic accuracy study, 199 patients with acute appendicitis were enrolled. The serum CRP level was evaluated in patients. Post-operatively, the patients were divided into simple and complicated appendicitis based on histopathological examination. Eventually, analysis of the CRP level and type of appendicitis was performed. Results: Fifty-three patients were categorized into complicated appendicitis and 146 patients into simple appendicitis. The median of CRP was significantly higher in the complicated group. Additionally, the optimal cutoff point was as follows: [65.0 (25.0) vs 25.0 (51.0); P-value 0.001]. The optimal cutoff point for CRP was more than 42 with 81.1% sensitivity (95% CI: 68.0 to 90.6), and 67.8% specificity (95% CI: 59.6 to 75.3). The positive (PPV) and negative predictive values (NPV), based on the prevalence of complicated appendicitis (26.6%) for optimal cutoff point, were 47.8% (95% CI: 37.1 to 58.6) and 90.8% (95% CI: 83.8 to 95.5). Conclusion: Our study revealed that evaluation of serum CRP levels could be useful and beneficial in the diagnosis of acute complicated appendicitis.