Score may determine when patients should seek treatment for strep throat

A score to diagnose group A streptococcal (GAS) pharyngitis that can be calculated by patients at home could save hundreds of thousands of visits annually by identifying the need for testing or treatment, a study found.

To help patients decide when to visit a clinician for the evaluation of sore throat, researchers conducted a retrospective cohort study among 71,776 patients aged 15 years or older who visited a retail health clinic from September 2006 to December 2008 with pharyngitis and were tested for GAS pharyngitis.

Researchers created a score using information from patient-reported clinical variables plus the incidence of local disease. The home score (actual range, 8 to 62; possible range 0 to 100) is based on demographic, historical, and biosurveillance data only, and not on a physical exam. The presence of fever or cough, the patient's age and the proportion of positive tests recently in the area were the factors in the score. Researchers compared the home score with the Centor score and other traditional risk assessment methods.

Results appeared in the Nov. 5 issue of Annals of Internal Medicine.

Among the 48,089 retail health visits of patients ages 15 years or older in the derivation set, 11,614 (24%) tested positive for GAS pharyngitis. In the validation set, 5,728 of 23,687 (24%) tested positive. Researchers found that using a home score of 10 as a cutoff had a sensitivity of 0.99 and a specificity of 0.04, with a negative predictive value of 0.90. They calculated that if patients aged 15 years or older with sore throat did not visit a clinician below this cutoff, 230,000 visits could be avoided annually in the U.S., and only 8,500 patients with GAS pharyngitis would be missed.

Researchers wrote, “Even without information from physical examination findings, the home score approaches the accuracies and overall performances of the existing validated scores. Clinicians could use the home score to interact with patients online or over the telephone. There may also be circumstances in which it would be safe for patients themselves to be guided by a home score application.”

An editorial noted some concerns, including that the biosurveillance data used in the model assumes an even prevalence across an entire community and that the study equated the presence of GAS in the upper respiratory tract with streptococcal infection, but they aren't the same.

A second editorial pointed out that while reducing clinic visits and health care costs for unneeded treatments is admirable, biosurveillance and other aspects of implementing this score carry their own burdens and costs. More practical strategies include a change in testing protocol to avoid testing patients with a very low risk for GAS pharyngitis, and using recommended generic antibiotics instead of more expensive ones, the author said.

“Acute pharyngitis has a typical duration of 3 to 5 days,” the second editorialist wrote. “Patients clinically improve each day. We should clarify that the evaluation of patients whose symptoms have worsened requires a different approach. Such patients have a separate differential diagnosis that physicians should consider; therefore, we should always caution our patients that they should return if their symptoms—especially fever, rigors, sweats, or unilateral neck swelling—worsen.”