BALTIMORE – In children with pharyngitis, it’s safe to skip group A Streptococcus testing if there are no exudates, children are 11 years or older, and there is either no cervical adenopathy or adenopathy without fever, according to a Boston Children’s Hospital investigation.
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The prevalence of group A Streptococcus among children who meet those criteria is 13%, less than the estimated asymptomatic carriage rate of about 15%. Among 67,127 children tested for strep and treated for sore throats in a network of retail health clinics across the United States, 35% fit the profile.
Investigators led by Daniel Shapiro, MD, a pediatrics fellow at Boston Children’s, concluded that “laboratory testing for GAS [group A Streptococcus] might be safely avoided in a large proportion of patients with sore throats. In doing so, we may avoid some of the downstream effects of unnecessary antibiotic use.” Incorporating the rules into EHRs “might help physicians identify patients who are at low risk of GAS pharyngitis.”
The study team tackled a long-standing and vexing problem in general pediatrics: how to distinguish viral from GAS pharyngitis. They often present the same way, so it’s difficult to tell them apart, but important to do so to prevent misuse of antibiotics. Health care providers generally rely on rapid strep tests and other assays to make the call, but they have to be used cautiously, because asymptomatic carriers also will test positive and be at risk for unnecessary treatment, Dr. Shapiro said at the Pediatric Academic Societies annual meeting.
To try to prevent that, the Infectious Disease Society of America (IDSA) recommends against strep testing in children who present with overt viral signs, including cough, rhinorrhea, oral ulcers, and hoarseness (Clin Infect Dis. 2012 Nov 15;55[10]:1279-82).
In a previous study at Boston Children’s ED, however, Dr. Shapiro and his colleagues found that 29% of children with overt viral features were positive for GAS, suggesting that the IDSA guidelines probably go too far (Pediatrics. 2017 May;139[5]. pii: e20163403).
“One might conclude that while it’s a good rule of thumb to avoid testing patients with viral features, some of the patients with viral features really do have GAS pharyngitis, so the recommendation to forgo testing in all these kids needs a little bit of refinement,” he said.
That was the goal of the new study; the team sought to identify viral features that signaled a low risk of GAS pharyngitis and, therefore, no need for testing. Low risk was defined as less than 15%, in keeping with the asymptomatic carriage rate.
The 67,127 patients were aged 3-21 years. Their signs and symptoms were collected at the retail clinics in a standardized form. The subjects had rapid strep tests, with negative results confirmed by DNA probe or culture.
Fifty-four percent had viral features, defined in the study as cough, runny nose, or hoarseness (oral ulcers weren’t collected on the form). The overall prevalence of GAS was 35%, similar to previous studies; 39% of children with no viral features tested positive for GAS versus 26% of children with all three. Exudates and age below 11 years were strongly associated with GAS among patients with viral features.
It turned out that just 23% of children without exudates were GAS positive; the number fell to 15% when limited to children 11 years or older, and to 13% when either no cervical adenopathy or adenopathy without fever were added to the mix.
There was no industry funding, and Dr. Shapiro didn’t have any disclosures.