Researchers have created a home test for strep throat that they say is almost as accurate as laboratory tests and could eliminate the need for doctor's visits for sore throat. This is according to a study published in the journal Annals of Internal Medicine.

Strep throat is a type of sore throat caused by a bacteria called Streptococcus pyogenes, also known as group A streptococcus (GAS).

This form of bacteria is highly contagious and can be spread through airborne particles when an infected person coughs or sneezes, or through touching infected surfaces.

When a patient visits their physician complaining of a sore throat, they may have a laboratory test carried out to determine whether their sore throat is bacterial or viral. However, a laboratory test may be unnecessary for patients who are deemed as low-risk for strep throat.

The research team from Boston Children's Hospital and the University of California, San Diego, says the newly created strep home test involves a scoring system that determines whether a patient's sore throat is viral or bacterial, potentially eliminating the need for doctor's visits.

The home scoring is based on a patient's personal health information that is provided by them directly and an assessment of any recent strep encounters within the general population.

The patient's scores are then compared to traditional "Centor" scores used in laboratory tests to determine whether a patient has strep throat. If a patient's score shows the likelihood of strep throat to be less than 10%, they are deemed as low-risk.

Doctor's visits 'could be reduced by 230,000 a year'

To determine whether the home strep test is accurate, the researchers analyzed 71,776 patients aged 15 years or older who had pharyngitis (sore throat) between 2006 and 2008.

Of these patients, 48,089 were tested for strep throat using laboratory tests at a health clinic, while 23,687 used the home strep test.

Of the patients who were tested during doctor's visits, 11,614 (24%) tested positive for group A streptococcus pharyngitis, while 5,728 (24%) tested positive using the home test.

From these results, the researchers estimate that if patients aged 15 years or older with sore throats who scored less than 10% on the home strep test avoided visiting the doctors for the "Centor" test, this could reduce doctor's visits in the US by 230,000 each year and reduce the number of patients prescribed "unnecessary" antibiotics for strep throat by 8,500 each year.

Commenting on their findings, the researchers say:

"The model, based on history and recent, local disease patterns without physical examination information, could help clinicians and patients estimate the likelihood of disease before a clinical encounter and help steer these patients to timely, appropriate care when needed.

In some instances, patients unlikely to have GAS pharyngitis might avoid, or at least delay, an emergency or outpatient visit."

Researchers have 'overestimated specificity'

However, in an editorial linked to the study, Robert M. Centor, from the University of Alabama, says that the researchers have "overestimated the specificity" of the home strep test.

"Derivation models almost always give better results than validation data sets," he says. "We should use the specificity that they found in their validation data as a more accurate estimate of how this model would work in the future."

He adds that although the goals of the researchers are "admirable," he doubts that the home test approach is practical or cost-saving for patients, and he details other areas in which savings could be made, such as using recommended generic antibiotic treatment for pharyngitis rather than more expensive options.