Runny noses, sneezing and itchy, watery eyes are some of the symptoms that cause millions of Americans to seek relief from allergists.
Bermice Garrett, a high school student from Columbus, is one of them.
“I broke out pretty bad so, hopefully, they will give something to me,” she said, while awaiting for the results of an allergy test at Ohio State’s Allergy Clinic.
The allergy test that Garrett took is called the skin-prick test, one of several traditional allergy tests available. Researchers have recently begun to study blood samples as an alternative test.
“I would expect this particular test would become more popular over the next two years,” said Sheryl Szeinbach, co-author of a study on the reliability of blood tests and a professor in pharmacy.
According to the study, researchers using the blood test found that nearly two out of three patients treated for allergies were not allergic. Among three types of blood tests, the ImmunoCAP allergy blood testing method was proven highly reliable and a more valid test than the other two.
Szeinbach said allergists commonly use the skin-prick test to determine whether the patients are allergic or not.
“The new study reinforces the importance of having additional diagnostic evidence to make the right decision for patients who have allergy-like symptoms,” she said. “The skin test alone is not definitive.”
Szeinbach also said an inaccurate diagnosis could have several effects on the patient. One is the cost for the medication that they don’t really need.
She said that people who have been misdiagnosed have a quality of life below that of someone who is accurately diagnosed and taking medication appropriately.
Dr. Charity Fox, an allergist at the Allergy Clinic in Davis Medical Research Center, said the skin-prick test that the Allergy Clinic uses for the patients is reliable and valid.
Fox disagreed about the large numbers of false positives attributed to the skin test, although she said that some methods of the skin test cause higher incidents of false positives because of inappropriate amount of extracts applied to the patients during the test or other inaccurate testing methodology.
“One of the studies shows that the prick test and the best invitro test (blood test) are roughly equivalent if they use the right extract and the (proper) method,” Fox said.
Fox said a study comparing the two, the skin test and the blood test, should be conducted.
“I’ve not seen any published data comparing to the blood test directly in the same patients head to head with the prick test,” she said. “I think the best way to establish what the relative accuracy of the two tests is, is to take the same patients and to be able to control. When that has been done, two methods are roughly similar.
“I use both (the skin test and the blood test),” Fox said.
The blood test is preferable for the patients who have very reactive skin or those who are on medication that would conflict with the accurate test reading, however, doctors can get information from the prick test that they don’t get from the blood test, she said.
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