Food allergy diagnosis by oral food challenge is safe, says study

A new study concludes that medical procedures known as oral food challenges, which are used in clinics to test people for food allergies, are very safe and rarely cause severe reactions.

A report on the study, led by researchers from the Baylor College of Medicine in Houston, TX, and Texas Children's Hospital, also in Houston, is published in the Annals of Allergy, Asthma and Immunology.

Lead author Dr. Kwei Akuete, a practicing allergist and member of the American College of Allergy, Asthma and Immunology (ACAAI), says, "Oral food challenges are a very important tool for anyone who wants to know if they have a food allergy."

Food allergy is a serious medical condition that arises when the body's immune system reacts to a harmless food protein, or allergen, as if it were a disease-causing germ.

The reaction is often unpredictable and ranges in severity from person to person, as well as over time in the same person. It can range from minor abdominal pain or hives on the skin to a severe and potentially fatal condition called anaphylaxis, accompanied by low blood pressure and loss of consciousness.

Up to 15 million people in the United States are affected by food allergy. Research also suggests that food allergies affect around 4 percent of children and adolescents in the U.S., where prevalence among children went up by 18 percent between 1997 and 2007.

Oral food challenge

As yet, there is no cure for food allergy, so the only way to prevent reactions is to avoid the foods that cause them.

In the U.S., 90 percent of severe allergic reactions are caused by eight food groups: crustacean shellfish, eggs, fish, milk, peanuts, soy, tree nuts, and wheat.

Food allergy is not the same as food intolerance, and its symptoms can be mistaken for other medical conditions. It is therefore important that any diagnosis is confirmed by a qualified allergist who can then advise a food plan that is tailored to the patient's specific allergies.

The new study concerns a type of noninvasive medical procedure called the oral food challenge (OFC), or feeding test.

During an OFC, a board-certified allergist invites the patient to eat increasing amounts of a food very slowly and monitors them very closely for any reaction.

OFCs are usually performed because other allergy tests, such as blood and skin tests, together with a careful medical history, have been inconclusive.

OFCs are performed in two modes: open and blinded. Open OFCs - in which both the patient and the administrator know which food is being tested - are more common in clinical practice. Blinded OFCs are more common in research.

OFCs found to be safe

For their study, Dr. Akuete and colleagues investigated the results of 6,327 open OFCs that were carried out between 2008 and 2013 in five food allergy centers across the U.S. The majority of the OFCs were carried out in patients under the age of 18.

They used a statistical method called meta-analysis to pool and analyze the data, and to determine rates of food allergy reactions and anaphylaxis.

The results showed that only 14 percent of the patients that had OFCs experienced any reaction, and only about 2 percent experienced anaphylaxis.

The reactions that were not anaphylaxis only occurred on one part of the body - for example, hives on the skin. These were classed as mild to moderate reactions, and most of them were treated with antihistamines.

Of the more severe reactions, the authors note, "19 OFCs resulted in patients being placed in hospital observation, and 63 were treated with epinephrine.

OFCs 'improve quality of life'

"Food challenges improve the quality of life for people with food allergies, even if they are positive," says senior study author Dr. Carla Davis, who is also a practicing allergist and ACAAI member.

Dr. Davis explains the importance of having the test sooner rather than later, saying, "When an OFC is delayed, sometimes people unnecessarily cut certain foods out of their diet, and this has been shown to lead to increases in health costs to the patient. A delay risks problems with nutrition, especially for children."

It is important to seek an accurate diagnosis so that a clear recommendation can be made about which foods to avoid, she adds.

"As OFCs are the 'gold standard' for determining if someone is allergic to a food, it is important they are both effective and safe. Our study showed OFCs are safer than prior studies estimated, and that OFCs should be routinely used to help determine if a food allergy exists."

Dr. Kwei Akuete