Sore throat is one of the more common presenting complaints to physicians’ offices. Despite its relative frequency, its management remains an area of considerable controversy. The best management scheme for diagnosis and treatment of streptococcal pharyngitis along with symptom management is debated with some routine in the literature.

The rationale for the aggressive diagnosis and treatment of pharyngitis is the prevention of rheumatic fever in both adults and children. Prevention of both primary and recurrent infections is dependent on the adequacy of treatment of group A, b -hemolytic streptococcus. The incidence of rheumatic fever has been on the decline throughout most of this century.¹ While the incidence of rheumatic fever is very low in most regions of the US, occasional clustering of patients has occurred.² The incidence of rheumatic fever may be as high as 3% in selected populations.³

The reasons for the steady decline in the incidence of rheumatic fever seen from the end of World War II to the late 1980s remain obscure, as do the reasons behind a sudden upsurge in reports cases seen in the last decade. According to the Institute for Clinical Evaluative Sciences (ICES), a non-profit research organization dedicated to conducting research that contributes to the effectiveness, quality, and efficiency of health care in the province of Ontario, Canada, only 8-20% of patients with pharyngitis actually seek medical care (http://www.ices.on.ca/docs/fb1410a.htm). This raises an obvious question about the value of treatment in preventing rheumatic fever and brings into question the role of other factors including the socioeconomic factors, drug resistant organisms and increased virulence.⁴

In 1995, the American Heart Association issued a Medical/Scientific Statement entitled, "Treatment of Acute Streptococcal Pharyngitis and Prevention of Rheumatic Fever." (http://www.americanheart.org/Scientific/statements/1995/109501.html) According to this evidence-based report:

• Viruses cause symptoms of acute pharyngitis more often than does group A, b -hemolytic streptococcus.
• Differentiation between viral and bacterial etiology is difficult based on history and clinical presentation.
• Throat culture, when properly obtained, is almost always positive in patients with streptococcal pharyngitis. Unfortunately, the throat culture cannot differentiate between patients who are chronic carriers of the bacteria with concomitant viral pharyngitis from those with acute bacterial infection.
• Antigen detection tests have high specificity but relatively low sensitivity. Patients with acute pharyngitis and a positive reaction to a streptococcal antigen test should be treated. A negative test is not conclusive. As with the throat culture, the antigen tests cannot differentiate between a chronic carrier state and acute infection.

In the mid 1990s, the ICES evaluated a "Sore Throat Score" (http://www.ices.on.ca/docs/fb1410a.htm). This scoring system was intended to improve the accuracy of group A streptococcal pharyngitis diagnosis.⁵ The four characteristics associated with streptococcal pharyngitis are:

1. Tonsilar exudate
2. Swollen anterior cervical nodes
3. History of fever of more than 38° C
4. Lack of a cough

The scoring system has a sensitivity of approximately 85%, with specificity in the 40% range. This is roughly equivalent to the sensitivity and specificity of a throat culture in detecting streptococcal pharyngitis. This scoring system has been used in a number of clinical settings and has been found to be reasonably reliable. The ICES review suggested that the probability of streptococcal pharyngitis increased with the number of characteristics present. With only one of four present, the probability of streptococcal pharyngitis is 6-7%; with two of four, 14-17%; with three of four, 30-34%. With all four characteristics present, the probability of acute streptococcal pharyngitis is 56%. Relying on the score alone would result in twice as many patients being treated with antibiotics as is necessary. Combining the scoring system with throat culture reduces unnecessary antibiotic therapy considerably.

From the ICES Review:

• If a patient does not have more than one of the four clinical findings, neither a throat culture nor antibiotics is indicated [Note: Both are expensive. The patient charge for a throat culture at the MGH is $52. Drug costs range up to almost $40 depending on the antibiotic chosen. (Table 1).]
• Most other patients should have throat cultures taken. A positive culture should be obtained before initiating antibiotic therapy.
• Patients presenting with all four characteristics have the highest probability of being culture positive. The decision to initiate antibiotic therapy should be based clinical reasons. 

Antibiotic therapy varies considerably in practice. It is important to note that no single antibiotic has been demonstrated to provide 100% efficacy. Penicillin is the drug of choice except in those with a penicillin allergy. Antibiotics do not speed symptom relief. Randomized trials suggest that antibiotics may provide significant symptom relief for sicker, febrile children. This does not appear to be true for adults. Symptoms associated with pharyngitis resolve in 3 or 4 days whether or not antibiotics are taken.

There has not been a significant change in the sensitivity of streptococcus to penicillin over the past 40 years.⁶ For penicillin-allergic patients, either erythromycin or a narrow-spectrum cephalosporin such a cephalexin (Keflex ) is recommended.

                                                                           TABLE 1

*Note: Costs are approximate, based on average wholesale price (AWP), 1999 Drug Topics Red Book

For the majority of patients with sore throat who do not have streptococcal pharyngitis, the use of simple analgesics such as acetaminophen, warm salt warm gargles (a quarter teaspoonful of salt per cup of water) and hard candy will provide symptomatic relief (http://www.ices.on.ca/docs/fb1410b.htm).

REFERENCES:

1. Bronze M, Dale J. The reemergence of serious group A streptococcal infections and acute rheumatic fever. Am J Med Sci 1996; 311(1):41-54.
2. Taubert KA, Rowley AH, Shulman ST. Seven-year national survey of Kawasaki disease and acute rheumatic fever. Pediatr Infect Dis J. 1994; 13:704-708.
3. Siegel AC, Johnson EE, Stollerman GG. Controlled studies of streptococcal pharyngitis in a pediatric population. I. Factors related to the attack rate of rheumatic fever. N Engl J Med 1961; 265:559-565.
4. Kaplan E. Global assessment of rheumatic fever and rheumatic heart disease at the close of the century: influences and dynamics of populations and pathogens: a failure to realize prevention? Circulation 1993; 88(4):1964-1972.
5. Centor RW, Witherspoon JM, Dalton HP et al. The diagnosis of strep throat in adults in the emergency room. Med Decision Making 1981; 1:239-246.
6. Shulman S. Evaluation of penicillins, cephalosporins and macrolides for therapy of streptococcal pharyngitis. Pediatrics 1996; 97(6S):955-959.