Comparative evaluation between rapid antigen detection test for streptococcal pharyngitis and throat culture in children

ABSTRACT

Acute upper respiratory tract infections in children may result in overuse of antibiotics as throat culture cannot be performed in every setting and results cannot be obtained early. The sensitivity of a rapid antigen-detection test [RADT] for group A streptococcal [GAS] pharyngitis is critical to whether the test is cost-effective arid to whether a confirmatory throat culture is needed. To assess the diagnostic value of rapid antigen detection test [RADT] for streptococcal pharyngitis in children and to compare it with throat culture. 600 children with signs and symptoms of acute upper respiratory tract infections were included in the study. Throat culture and RADT were performed and prevalence of GAS pharyngitis was assessed. Diagnostic value of RADT was determined. Their mean ages was 5.4 +/- 4.1 years [ranges 8 months-18 years, median 8 years]. The patients were subdivided into four groups according to their ages-group 1 0-4 years [n = 152]; group 2 5-9 years [n = 236] and group 3 10-14 years [n = 157] and group 4 15 years and older [n = 55]. The prevalence of GAS pharyngitis was 45.1% [n = 270/600] with RADT, and was 34.1% [n = 205/600] with throat culture. With respect to the distribution of positive cases by age, the greatest level of occurrence was between 10-14 [51%] years of age and lowest in children between 0-4 [22.1%] years. Considering the culture as the "gold standard" and considering all patients, the RADT showed a sensitivity of 87.9%, a specificity of 93%, a positive predictive value or 90.9% and a negative predictive value of 90.7%. Symptoms like scarletiform rash, tonsiller exudate and absence of cough were more frequent among the subset of children with positive RADT, with statistical significance [p < 0.001]. Diagnostic value of RADT is high and can be used safely in populations where streptococcal pharyngitis is common and a negative RADT result in our pediatric practice still requires a confirmatory throat culture