Diagnostic accuracy of combining C-Reactive protein and Alvarado Score among 2-to-20-year-old patients with acute appendicitis suspected presenting to Emergency Departments.

Objective: Main objective was whether the combination of C-Reactive Protein (CRP) and Alvarado Score (AS) increase the diagnosis accuracy of AS among 2-to-20-year-old patients with suspected acute appendicitis presenting to Emergency Departments.

Methods: This is a secondary analysis of prospective cohort study consecutively including all patients from 2 to 20 years of age attended for suspected acute appendicitis in 4 Spanish Emergency Departments during 6-month period. We collected demographic, clinical, analytic and radiographic, and surgical data. AS categories were retrospectively calculated as low (0-4 points), intermediate (5-6 points) or high (7-10 points). The cut-off levels were >0.5 mg/dl for CRP. The outcome was diagnosis of acute appendicitis within 14 days of the index visit.

Results: A total of 331 patients with suspected of acute appendicitis (mean age 11.8 (SD 3.8) years; 52.9% males) were recruited. According to AS, 108 (32.6%) were at low risk, 76 at (23.0%) intermediate risk and 147 (44.4%) at high risk of acute appendicitis. One hundred and sixteen (35.0%) cases had confirmed histopathological diagnosis of acute appendicitis. The AUCs of ROC were 0.76 (0.70-0.81) for AS and 0.79 (95% CI 0.75-0.84) for CRP-AS being the difference statistically significant (p=0.003). The CRP for diagnosis acute appendicitis in low risk AS group had negative predictive value of 95.8% (95%CI 87.3-98.9) and likelihood ratio negative of 0.4 (95%CI 0.2-1.0)..

Conclusions: CRP-AS has shown to increase the diagnostic accuracy of AS for acute appendicitis. This approach may be useful to rule out the diagnosis of acute appendicitis in paediatric patients attended for abdominal pain suggestive of acute appendicitis.