Vol 53: november • novembre 2007 Canadian Family Physician • Le Médecin de famille canadien 1961 FP Watch • Surveillance médicale ARI Series Acute sore throat Graham J. Worrall MBBS MSc MRCGP FCFP The pharynx is the garbage dump of the bronchial tubes and the nasal passages. Sir William Osler A cute sore throat accounts for about 4% of all FP visits; only a small proportion of people with sore throats seek medical attention. • Sore throat is the second most common acute infec- tion seen by FPs. • Fewer than 1 in 10 people with sore throats go to see their FPs. • Sore throat is predominantly a disease of youth and the early school years. • Sore throats are more common in autumn and winter. Cause The most important bacterial cause of a throat infection is group A β -hemolytic streptococcus (GABHS), which is responsible for about one-third of sore throats in chil- dren aged 5 to 15 years. In adults and in younger children, only 10% of sore throats are caused by GABHS. Carriers of GABHS do not need treatment. • Viruses are responsible for 85% to 95% of adult sore throats. • Viruses cause 70% of sore throats in children aged 5 to 16. • Viruses cause 95% of sore throats in children younger than 5 years. • The most common bacterial cause of sore throat is GABHS. • At least 30% of GABHS cultured in primary care are due to carriers who are not sick and are at very low risk of infecting other people. Clinical course and diagnosis In otherwise healthy people, a sore throat is usually self- limited and rarely produces serious aftereffects. Typical GABHS patients are children aged 5 to 15 who present with fairly acute onset of fever and sore throat. • Headache, nausea and vomiting, malaise, dyspha- gia, and abdominal pain might be present. Sore throat decision rule The sore throat decision rule can identify both patients who are so likely to have GABHS that a confirmatory test is not needed and patients who are so unlikely to have GABHS that further testing is unrewarding. Using the rule will successfully identify most patients who need treatment for GABHS infection, while decreasing antibi- otic use for sore throat by about 80%. The 4 most useful features to look for in diagnosing GABHS are enlarged submandibular glands, a throat exudate, fever, and absence of cough and runny nose. Use the following sore throat rule to decide which adults are most likely to have GABHS infection: • 0 or 1 feature present—GABHS is unlikely; • 2 features present—diagnosis uncertain, consider further testing; and • 3 or 4 features present—GABHS is likely. Rapid antigen detection tests Office testing kits that determine whether a throat swab contains antistreptolysin antigen are now available and inexpensive. In patients with an indeterminate sore throat rule score, consider using such a test. Antibiotic treatment In antibiotic trials, 90% of both treated and untreated patients were symptom-free by the end of 1 week. Antibiotics shortened the duration of symptoms, but by a mean of only 16 hours overall. Most patients get bet- ter without antibiotics; however, antibiotics do modestly reduce symptoms. Antibiotics do protect against the following: • acute rheumatic fever (number needed to treat [NNT] =4000), • Cough and rhinorrhea are usually absent. • Edema and erythema of the tonsils and pharynx are usually present. • Anterior neck glands might be enlarged and tender. • A non-adherent pharyngeal exudate might be present.