Centor scores associated poorly with rapid antigen test findings in children with sore throat.

The Finnish Current Care Guideline recommends rapid antigen tests as the primary diagnostic tool for both adults and children with Centor score ≥ 3. We aimed to analyze the association of Centor score and rapid antigen test positivity of group A streptococcal pharyngitis (GAS) in Finnish children. We performed a retrospective single-center study from July 2019 to June 2022. We included all children aged 0-15 years based on ICD-10 diagnostic codes for acute pharyngitis. We manually extracted the data from the electronic healthcare records. We extracted the information on Centor score signs and symptoms, rapid antigen tests, throat cultures, and C-reactive protein (CRP) levels. Comparisons were made between different groups by calculating a difference of two proportions with 95% confidence intervals. A total of 464 children were included and rapid antigen tests were taken from 433 (93.3%). We did not detect any significant association between rapid antigen test positivity and Centor scores. Sensitivity of Centor score ≥ 3 for rapid antigen test positivity was 22.3 (95% confidence interval 17.3-27.9) and specificity 79.0% (72.4-84.8). Positive throat culture was found in 17.1% of the patients with negative rapid antigen test. Centor scores correlated positively with CRP levels, but elevated CRP did not predict positive antigen test results.

Conclusion:  The Centor score alone does not seem to be of any utility in guiding the diagnosis of suspected streptococcal pharyngitis. Microbiological testing remains necessary for accurate diagnosis and CRP should not be used to differentiate viral and bacterial pharyngitis cases.

What is known: • The Centor score is a clinical prediction model for differentiating Group A streptococcal (GAS) pharyngitis from viral pharyngitis. • Finnish Current Care Guideline recommends rapid antigen testing in patients with Centor score ≥ 3 for diagnosing GAS infections and antibiotics prescribed based on confirmed test results.

What is new: • The Centor score alone does not seem to have any use in guiding the diagnosis of suspected streptococcal pharyngitis in children. • Microbiological testing remains necessary for accurate diagnosis in patients with sore throat.