Justin, a 13-year-old patient who has had sore throat, fever and swollen glands for two days, presents to your office. On examination, he has exudative tonsillitis and tender anterior cervical nodes but no posterior cervical adenopathy. What is his probability of having group A beta-hemolytic streptococcal (GABHS) pharyngitis?
The evidence-based answer is at hand
If you don’t have all the evidence you need to answer this question already in your mind, you’re not alone; physicians simply cannot expect to remember all the latest clinical evidence.1–4 But you can have the evidence at your fingertips when you need it. The sore throat encounter form that can be downloaded below is an evidence-based guide you can implement easily in your practice.
The form incorporates a strep score calculator developed by McIsaac3 – the best one available. It is simple to use, takes age into account and has been tested and found to be accurate in a group of over 600 adults and children presenting with sore throat to family physicians. Using the encounter form, you could quickly calculate Justin’s strep score at 5, meaning there is a 52-percent chance that he has GABHS pharyngitis. It would then be reasonable to treat him empirically. Another option for these high-risk patients is to base treatment on the results of a rapid strep test, or to obtain a throat culture and call the patient in two days with the results. If the culture is negative, you could discontinue antibiotics, recognizing the potential for false-negative culture results when the pretest probability is sufficiently high.
The encounter form takes into account the group of signs and symptoms that best help make the differential diagnosis: tonsillar swelling or exudates, tender anterior cervical nodes, history of fever or a measured temperature of >100.4 F, absence of cough and age. A review looking at individual signs and symptoms found that exposure to strep throat infection in the previous two weeks not surprisingly increases the risk of strep. It also found that the presence of a scarlatiniform rash or palatine petechiae is uncommon, but very specific for the diagnosis.4
To familiarize yourself with the form – and incidentally to see how well you have been doing in managing GABHS pharyngitis – consider using it to audit chart notes for a few recent visits for sore throat. And keep it close at hand throughout the sore throat season.
This article is part of a series that offers evidence-based tools to assist family physicians in improving their decision making at the point of care. The series is produced in partnership with American Family Physician. A related article, which also includes the sore throat encounter form, appears in the Sept. 1, 2003, issue of AFP.
Watch future issues of American Family Physician and Family Practice Management for similar forms useful in dealing with other common or important conditions seen in your practice. Their use can help even the busiest of physicians make evidence-based decisions at the point of care.