For example, an adult patient (with a 10% baseline risk of GABHS) who presents with a fever but no cough could have a pretest probability for GABHS pharyngitis ranging from 8% to 41%, depending on the presence of exudates and adenopathy.
The number needed to treat (NNT) for antibiotics given to GABHS-positive patients is 3.5 for resolution of symptoms by day 3; for GABHS-negative patients it is 5.5, and for patients who did not have a culture, it is 14.5. When properly prescribed, antibiotics decrease communicability of GABHS to 24 hours, and symptoms by 1 day (NNT=5 patients to decrease symptoms).
Antibiotics also decrease the incidence of rheumatic heart disease (NNT=100) and peritonsillar abscesses. Due to the decreased incidence of glomerulonephritis, the evidence is inadequate to determine the role of antibiotics in preventing this complication.3
Recommendations from others
Although guidelines do not specifically address the treatment of symptomatic family members over the phone, the Infectious Disease Society of America states that the diagnosis of GABHS pharyngitis be confirmed by appropriate laboratory testing after clinical and epidemiological suspicion.4 The American College of Physicians state that a positive confirmatory laboratory test or Centor score of 4 could reasonably warrant treatment.3