Sore throat and upper respiratory tract infection are the most common acute complaints encountered by physicians. It is a challenge to tell which patients with sore throat have a viral illness and which have streptococcal pharyngitis. Several attempts have been made to develop clinical prediction rules that help physicians make this distinction. McGinn and colleagues prospectively evaluated a simplified version of the Walsh clinical predictors as a decision-making tool in the diagnosis of streptococcal pharyngitis.

The study population consisted of adult patients who presented as walk-ins to the primary care center at an inner city hospital. The patients had symptoms of upper respiratory tract infection or sore throat, and were assessed by physicians using the Walsh predictors (see accompanying table). One point was assigned for the presence of each predictor. A throat culture for group A beta-hemolytic streptococcus was performed in each patient.

The investigators enrolled 171 consecutive patients with similar symptoms. Five patients were excluded because throat culture results were unavailable. The remaining 166 patients had a mean age of 35 years; 39 of the patients were men. Cultures were positive in 39 patients (23 percent). Throat culture results for each clinical score were then determined (see accompanying table).

The authors conclude that the simplified Walsh predictors for streptococcal pharyngitis can be used to stratify patients into treatment groups. In patients with a low probability of streptococcal pharyngitis (score of −1), only follow-up is needed. Those in the intermediate group (score of zero or 1) could be tested further, treated, or followed, depending on physician preference. Patients with a high probability of disease (score of 2 or 3) should be treated empirically with an antibiotic.