The tool requires data that are not yet readily available. But the study's authors from Boston Children's Hospital found the tool could potentially prevent 230,000 trips to U.S. doctors' offices every year for suspected strep throat.
The new tool, he said, could help people realize their risk of strep throat is low and stop them from making an appointment with their doctors. That may prevent them from getting unnecessary tests and unnecessary treatments - like antibiotics, which contribute to the problem of drug resistance.
Currently, about 12 million Americans visit doctors every year with sore throats, the researchers write in the Annals of Internal Medicine.
Accepted medical guidelines suggest doctors use an office-based tool that takes into account symptoms and physical examination results to determine a person's risk for strep throat. If the risk is low, guidelines recommend against testing or treating the patient.
For the new study, the researchers used information collected between September 2006 and December 2008 from 71,776 people over age 15 who visited CVS MinuteClinics in six states for sore throats.
They used people's medical records and strep test results to test a tool that calculated a "home score." It's similar to the one used in doctors' offices.
"The tool that the doctors use includes physical examination findings," Fine said. "We've removed those for the home scores so that anyone without medical training can assign themselves a score based two symptoms - fever and cough."
The tool also takes into account how common strep throat has been in the person's community during the past two weeks before calculating the home score.
"The thing here is that what you want to know the most â¦ is do the people around you have strep throat," Dr. Kenneth Mandl, the study's senior author, said.
That number, however, is not commonly available in most areas.
The tool measures risk on a scale from 0 to 100. For the new study, anyone with a score below 10 was considered at low risk for strep throat.
Overall, Fine and his colleagues found that 90 percent of the people who scored below 10 on the at-home tool would have tested negative for strep throat. That means there would be 27 fewer doctors' visits for every one person with strep throat who was missed by the tool.
As for those people with strep throat who would be missed, Mandl said the chance for them to go on and have serious complications is small.
"The nice thing about strep throat is that complications are rare," Mandl said.
Dr. Robert Centor, who wrote an editorial accompanying the new study, said it's an admirable goal to try to prevent unnecessary doctors' visits.
"I just don't think it's practical," Centor, who created the dominant tool doctors use to measure strep risk, told Reuters Health. He's the regional dean for the University of Alabama Huntsville Regional Medical Campus.
For example, Centor questioned whether an 18-year-old person would remember to look at an application like this tool before calling a doctor's office. He also said it would cost money to conduct surveillance strep throat tests to calculate its prevalence in different areas.
"It is totally unrealistic to think that real-time surveillance for group A streptococcus (bacteria that cause strep throat) is going to be carried out in any community," Dr. Edward Kaplan, who also wrote an editorial accompanying the new study, said.
Kaplan added that the prevalence of strep also varies within communities with parents of young children having a different risk than those children's grandparents, for instance.
"I think one could make a good argument that this isn't a one-size-fits-all argument," Kaplan told Reuters Health. He's a professor of pediatrics at the University of Minnesota Medical School in Minneapolis.
Mandl, however, said people could make use of the data already collected by hospitals and emergency departments to measure prevalence. They'd just need to create an application to align the data correctly and get permission to use them.
"The goal now is to validate the score prospectively - going forward - with real patients in a real clinical setting," he told Reuters Health. That study is already underway.
As for patients, Centor said, "The most important thing people should know is if the sore throat lasts longer than three or four days and is not getting better, you need to look at it seriously."
SOURCE: http://bit.ly/Ms1ZbQ Annals of Internal Medicine, online November 4, 2013.