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Strep throat risks called exaggerated, Tx rationale changed.

ASPEN, COLO. -- The risk that a sore throat will lead to rheumatic fever has always been vastly exaggerated, and it may be lower now than it once was. In fact, the risk is one of the major myths of medicine, Dr. Michael Radetsky said at a conference on pediatric infectious diseases sponsored by Children's Hospital, Denver.

That means any approach--rapid antigen test or culture, or empiric treatment or not--can be justified, said Dr. Radetsky, a pediatric infectious diseases consultant from Albuquerque, N.M.

"The whole issue of strep disease is now shifting from an issue of real medicine--meaning treating real disease--to an issue of relationship with the family," he said.

Last year, a group at Michigan State University, East Lansing, attempted to develop a rule for when to use a rapid antigen test versus when to culture a patient with pharyngitis for group A hemolytic streptococcus (GAS) infection, based on a cost analysis. Their investigation is very enlightening, Dr. Radetsky said.

The article raises "every serious issue that if we had time we would be thinking about, regarding what we should do about the entire issue of looking for strep throat," he said. The first interesting facet of this study is that in their analysis the researchers found that there are no current, accurate estimates for calculating the risk and incidence of peritonsillar abscess or acute rheumatic fever.

To develop their risk estimate of acute rheumatic fever, they had to go back to 1961, to the outbreak in New York City in which there were 2 cases among 608 cases of untreated GAS--for an incidence of 0.328% (Pediatrics 2006;117:609-19).

Since then--according to the available, albeit scanty, evidence--the incidence of GAS has been reduced by 98%. So the investigators multiplied 0.328 by 2%, which gave them a current estimate of a risk of acute rheumatic fever of 1 in 15,000 cases of untreated disease. Of those, only 10% will have complications and 1% will die, while treatment appears to reduce the risk of acute rheumatic fever by 88%, the study concluded.

"That was their estimate; I don't think anyone has done it better," Dr. Radetsky said.

The incidence of peritonsillar abscess, also never well studied, has been estimated at 0.5%-3%, and treatment of pharyngitis appears to reduce the incidence by only one-sixth or one-ninth, the investigators said.

They concluded in their analysis that treatment needed to be based on some kind of testing, because treating everyone and treating no one were not cost-effective. But, whether a rapid test or a culture is used depends on the costs, which vary in different areas.

But Dr. Radetsky said the study needs to be given deeper consideration.

The study shows that the risk of any kind of complication in a patient is extremely low.

The rationale for treating streptococcal pharyngitis has evolved over the years, he noted. Initially, it was to prevent rheumatic fever. Then it was to prevent peritonsillar abscess. Now it is also justified to enhance recovery and prevent contagion.

But, treatment has been shown not to speed recovery much, and treating to prevent contagion also is not likely to make much difference, because it is estimated that for every patient with a sore throat who sees a doctor, four to six people do not. Moreover, 15% of schoolchildren at any one time are carriers of GAS, so it is more likely that any one patient with GAS will acquire it at school than that they will be the source of an outbreak.

Given those facts, the physician has two obligations regarding GAS, Dr. Radetsky said.

One is to practice in whatever way fosters the therapeutic relationship with a patient and his or her family.

The second is to confine antibiotic use.

He recommended using a culture rather than a rapid antigen test or not testing at all to confine antibiotic use. That way, you give the patient a few days to get better before prescribing. To the family, the physician can explain that, even if the child does have GAS, waiting a few days will give the child a better opportunity to develop immunity to that particular serotype.

Moreover, treating with a second- or third-generation cephalosporin for 5 days, instead of using penicillin for 10 days, reduces the use of antibiotics and probably has superior efficacy, at least according to one recent metaanalysis (Pediatr. Infect. Dis. J. 2005;24:909-17).

"You have just cut the number of days on antibiotics in half," he said.

Dr. Radetsky also advocated using the technique of the deferred prescription, to be used only if the culture comes back positive or if the patient gets worse.

"The justification for doing what we do is becoming slimmer and slimmer, so that the continued pursuit of group A streptococcal pharyngitis is really driven by an outdated notion of risk, and a self-perpetuated habit," he added.


Sacramento Bureau
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Title Annotation:Infectious Diseases
Author:Kirn, Timothy F.
Publication:Pediatric News
Date:Dec 1, 2006
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