This includes properly conducted elimination of and subsequent oral challenge with foods suspected of causing allergic reactions based on the medical history, skin testing results, or in vitro testing results.
Of these procedures, the double-blind placebo-controlled food challenge (DBPCFC) is the most reliable method to help diagnose and confirm food allergy and other adverse food reactions because it eliminates both patient and observer bias. However, in a clinical setting where minimal bias is suspected, open food challenges may be preferable because blinding of the food is often not required.
Conduct any food challenge in a clinic or hospital setting with the personnel and equipment necessary to treat a systemic allergic reaction available at all times. Patients undergoing a food challenge should not be on beta-blocker medications or any medication that might interfere with the treatment of anaphylaxis. Obtain intravenous access in patients with history findings that indicate the potential for a systemic reaction.
If the history of the patient suggests an anaphylactic reaction is possible following food ingestion, do not perform an oral food challenge.
Open food challenge
This test involves the patient ingesting the suspected food, prepared in its customary fashion (ie, the challenge food is not disguised in any way).
Both the patient and the observer (eg, physician, nurse) are aware of the food being ingested.
The open food challenge is best used in clinical practice when patient and physician bias is minimal.
This type of challenge is typically used when the skin test results for the suspect food are negative or if a specific food reaction is unlikely.
Whenever the results are equivocal, perform a blinded challenge.
Patients with histories of a previous reaction should never perform an open food challenge at home, even if the chance they will develop severe symptoms is remote.
Single blinded food challenge
This challenge involves the patient ingesting the suspected food disguised in a challenge food so the patient is unaware of the contents.
This type of challenge, which is suitable for clinical practice and some research investigations, is designed to reduce patient bias during the procedure. However, subjective attitudes regarding the outcome of the challenge cannot be completely eliminated.
This test is also useful for screening patients for entry into studies in which the findings will be unequivocally confirmed by DBPCFC results.
Double-blind placebo-controlled food challenge
DBPCFC involves ingestion of the suspected food disguised in another food so that both the patient and observer are unaware of the contents of the challenge.
This type of challenge is designed to reduce both patient and observer bias and subjective attitudes during the procedure.
Always perform this challenge in a clinic or hospital setting.
Consider this the criterion standard for diagnosing food allergy, especially in research investigations. Currently, it is the only completely objective method for determining the validity of the history of an adverse reaction to a food.
Do not perform a challenge if the patient has a clearly convincing history of a severe life-threatening anaphylactic reaction following the isolated ingestion of a specific food.