Two Questions May Rule Out Strep Throat
In the near future, researchers report, it may be possible to click on an app, answer two questions about your symptoms and find out whether a seriously sore throat is actually a strep infection.
"Those questions would be: Do you have a cough, and have you had a fever in the last 24 hours?" said study author Dr. Andrew Fine, a pediatric emergency medicine specialist at Boston Children's Hospital. High fevers are a hallmark of strep infections, while coughs are not.
In a new study of more than 70,000 patients with sore throats, those two questions and an accounting of how common strep infections were within a local area ruled out cases of strep throat nearly as well as lab tests did.
"This enables us to use the test of time," said co-study author Dr. Kenneth Mandl, a professor of bioinformatics at Harvard. "If we determine that you're low risk and most cases will not have an important complication from strep anyway, then you can be followed clinically rather than come in for a test right away, and you may improve."
The researchers think that if the new test was widely used, it could save hundreds of thousands of unnecessary trips to the doctor each year and cut down on the overprescribing of antibiotics.
The study will be published Nov. 5 in the Annals of Internal Medicine.
The question of what to do for adults who have bad sore throats is a tough one, even for doctors.
About 15 million Americans see a doctor for a sore throat each year, and 70 percent of them get antibiotics to treat it, according to the Infectious Diseases Society of America. That's far more than the 20 percent to 30 percent of children and 5 percent to 15 percent of adults who actually benefit from taking the powerful drugs.
The problem is that most sore throats are caused by viruses, not bacteria, so antibiotics don't help clear up the infection. Taking antibiotics when they aren't needed can cause severe diarrhea and it contributes to the problem of antibiotic resistance -- when bacteria can no longer be killed by the drugs that are available to fight them off.
But cases of strep throat, which is caused by bacteria, can be more dangerous.
"There are both medical, as well as considerable public health, reasons that we are concerned about strep throat," said Dr. Edward Kaplan. A pediatric infectious disease specialist at the University of Minnesota, in Minneapolis, Kaplan wrote an editorial that accompanied the study.
These infections are highly contagious, and they may spread throughout the body, causing rashes, joint pain and lasting damage to the heart or kidneys.
Such serious aftereffects are rare, Kaplan said, but "they're still common enough to cause mischief."
Kaplan pointed to outbreaks of rheumatic fever caused by strep infections in Utah in the 1980s and 1990s, which sickened hundreds of adults.
The fear of missing strep infections combined with patient expectation that they'll get an antibiotic leads a lot of doctors to overtreat sore throats, he said. So, tools like a home test app could fill a need.
The problem, Kaplan said, is that the test requires information about how common strep infections are in a local area, but strep infections are not reported publicly.
In the study, researchers relied on data generated by MinuteClinics, a chain of urgent care centers located in CVS drugstores.
MinuteClinics give every patient who comes in with a sore throat a test for strep bacteria. Researchers divided the number of positive results by the total number of patients tested in the last two weeks to calculate risk scores.
The study found that 90 percent of patients who were at low risk for strep based on their home test score also had negative lab tests for strep at MinuteClinics.
But that kind of universal testing clashes with current clinical guidelines.
In a sense, the accuracy of the test depends on overtesting in the first place, which drives up health care costs, said Dr. Robert Centor, an internist at the University of Alabama at Birmingham. He wrote a second editorial on the study.
Centor thinks it would be much less expensive to get doctors to just follow clinical guidelines, and to prescribe generic antibiotics when strep is detected.
Centor also wondered whether people would actually use such an app, which only applies to people over 15 years of age.
"It fails the eyeball test to me. Does it look like people will do it?" he asked.
The study authors were more hopeful. They say health care is changing to reward doctors who provide good care without overtreating their patients.
"We think that tools that improve the accuracy and the judicious use of testing will actually be quite welcome in most segments of the medical community," Mandl said.
Visit the U.S. Centers for Disease Control and Prevention for more on strep throat.