Your throat hurts so much that you just want to stay curled up on the couch. But you’re worried that a strep infection might be to blame, so you drag yourself to the doctor’s office. Wouldn’t it be nice if there were a test you could take yourself to rule out strep—without having to leave the comfort of home?

Well, according to a new study, there is a self-test that can determine with a good degree of accuracy whether or not a sore throat is likely to be from strep. And you don’t need a swab or any apparatus, in fact. All you need to do is ask yourself two simple questions…

THE TWO KEYS

Sore throats lead to 12 million visits to the doctor’s office, health clinic or emergency room in the US each year. Only about 10% of sore throats in adults (and about 25% in children) are due to the group A Streptococcus bacterium. A definitive diagnosis of strep requires swabbing the throat and then running a test (a throat culture or DNA probe). When a strep test is positive, antibiotics generally are warranted because untreated strep can lead to rheumatic fever, scarlet fever, heart damage and/or kidney damage. However, the vast majority of sore throats are due to common viruses that won’t respond to antibiotics. Why not give antibiotics just in case without bothering to test for strep? Because the drugs can cause side effects such as severe diarrhea…and overuse contributes to antibiotic resistance.

Researchers wanted to explore whether there was a way that regular people, at home, could determine whether they were at very low risk for strep and thus could safely wait to see whether their symptoms would clear up on their own. For the study, the researchers used data provided by CVS, the drugstore chain that operates MinuteClinics. Everyone who visited a MinuteClinic complaining of a sore throat was given a rapid strep test and also questioned about symptoms. Over the course of two years in nine markets around the country, there were 71,766 visits by sore throat patients age 15 or older…24% of those ended up testing positive for strep.

When doctors check for strep, they look for swollen lymph nodes in the neck plus fluid or pus around the tonsils. But patients generally cannot check for such signs themselves. Because the aim of this study was to explore a do-it-yourself system that patients could use, the researchers focused on patients’ reports of symptoms that could be assessed without a physical exam—such as fever, cough, headache, earache, stomachache, nausea, difficulty sleeping, etc.

After analyzing all the symptom reports and strep test results, the researchers determined that just two questions—Have you had a fever in the last 24 hours?…and Do you have a cough?—generally were sufficient to determine whether the likelihood of strep was low enough that a person could skip the doctor visit and strep test. Explanation: Strep usually is accompanied by fever, whereas a cough usually indicates a virus.

WHEN STREP IS GOING AROUND

There was actually more to this study, because the researchers also factored in the “local recent incidence of strep,” meaning the percentage of strep tests done within a given region during the previous 14 days that turned out to have positive results. By combining information about local strep outbreaks with the fever/cough clues, it was possible to predict even more accurately whether a given patient did or did not have strep.

Someday soon, a smartphone app or Web site might provide the public with that kind of local outbreak information by Zip code. In the meantime, you can get a sense of this simply by phoning your doctor’s office and asking whether strep is “going around” in your area.

Bottom line: If you have a sore throat, you should get tested for strep if you have or recently had a fever and you do not have a cough—particularly if your doctor tells you that he’s been seeing a lot of strep lately…or if you are the type of person who prefers to err on the side of caution.

But you may want to wait a few days if you have not had a fever or if you have been coughing—especially if your doctor says that there’s no current strep outbreak in your area—to see if the sore throat clears up on its own, as viruses generally do.

Caveat: These guidelines are intended for adults. Children who have sore throats, with or without a fever or cough, generally should see their doctors to get tested for strep because the infection is more common among kids. And even in adults, these guidelines are not foolproof—so if your symptoms worsen, do get yourself to the doctor and get tested for strep.