Common questions about TRUE Test (FAQ)
Q: Is the TRUE Test different from a standard skin prick test for allergies?
Official information indicates that the T.R.U.E. Test is used to help diagnose Allergic Contact Dermatitis (ACD), which is a delayed-type hypersensitivity reaction. This process is different from a standard skin prick test. Prick tests are typically used to check for immediate allergic reactions, while the T.R.U.E. Test assesses a delayed response that takes several days to appear.
Q: What is the role of the negative control patch on the TRUE Test?
According to the official product information, the T.R.U.E. Test includes one negative control patch that contains no allergens. The purpose of this control is to help confirm that any reaction at a test site is caused by one of the allergens and not just irritation from the tape or the application process itself.
Q: Why is the test typically applied to the patient's back?
Regulatory guidance instructs that the test panels be applied to the healthy skin of the back. The back is often used because it provides a large surface area for the panels and is less likely to be affected by movement and friction.
Q: Is TRUE Test considered the standardized method for patch testing?
Regulatory documents describe the T.R.U.E. Test as a standardized, ready-to-use epicutaneous patch test system that provides a uniform dose of allergens to the skin. This unique design contributes to its standardization in identifying contact allergies.
Q: What is the difference between an allergic reaction and an irritant reaction on the test site?
Official documents acknowledge that irritant reactions can occur during testing and may sometimes be difficult for a professional to distinguish from a true allergic reaction. Irritant contact dermatitis is listed as a potential adverse reaction. If interpretation is unclear, a retest may be considered by the healthcare professional.
Q: What activities must be avoided while wearing the TRUE Test patches?
The official protocol advises avoiding excessive sweating and excessive physical activity during the testing period. The protocol recommends limiting these activities to help maintain adhesion of the panels and prevent the loss of test material.
Q: Are there any specific lotions or creams that must be avoided on the back before the test?
The official label describes the requirement to avoid the use of alcohol or other irritating substances on the skin before testing. Clinical instructions also advise stopping general moisturizers, lotions, or creams in the area for a specified period prior to application.
Q: How is the skin prepared just before the TRUE Test panels are applied?
Regulatory guidance describes that the test should only be applied to healthy skin that is free of scars, acne, or dermatitis. The label describes the requirement to avoid applying the test to recently tanned or sun-exposed skin, and to avoid using alcohol or other irritating substances on the skin beforehand.
Q: How are the positive reactions on the test site graded or measured?
Official information indicates that the evaluation of positive reactions is based on the method recommended by the International Contact Dermatitis Research Group (ICDRG). This group uses a specific ranking scale to grade the intensity of the delayed immune response.
Q: What does a 'negative' result on the TRUE Test mean for a patient?
A negative result indicates that the patient did not react to the 35 specific allergens contained on the test panels. However, the official label notes that negative results do not rule out the possibility of sensitivity to other allergens not included on the test.
Q: Are there any known long-term side effects from the components of the TRUE Test?
The official label warns of Persistent Reactions which may remain visible for weeks or months after the patches are removed. Regulatory studies focused on the diagnostic period; therefore, official information does not contain sufficient data regarding outcomes beyond the standard follow-up period.
Q: What is the current state of research evidence for the accuracy of the TRUE Test in diverse populations?
Regulatory data confirm that the T.R.U.E. Test has been studied in both adults and pediatric populations (ages 6 through 17). Clinical studies were largely designed to assess diagnostic performance based on frequencies of positive, negative, irritant, and doubtful reactions.
Q: How long has the TRUE Test been an established diagnostic tool for contact dermatitis?
Studies and official information indicate that the T.R.U.E. Test is a result of many years of research aimed at creating a standardized patch testing system. The FDA has approved multiple versions of the test system, reflecting its established role as a standardized aid in diagnosis.
Q: Is it possible to shower or get the test area wet during the testing period?
The official protocol advises against getting the panels and surrounding area wet. Therefore, activities like showering, bathing, or swimming are not allowed during the 48-hour application period to maintain the adhesion of the panels.
Q: What steps should be taken if a TRUE Test patch begins to loosen or fall off?
The official instructions indicate that if necessary, a healthcare professional may use hypoallergenic surgical tape for increased adhesion around the outside edges. If the patch significantly loosens, the protocol is for the patient to notify their healthcare provider.
Q: What is the purpose of the medical pen markings placed around the patches?
Regulatory documents describe that medical marking pen markings are made on the skin to indicate the exact location of the patch sites. These markings are necessary to allow the physician to align and properly evaluate any reactions after the panels are removed.
Q: What happens if a patient sweats a lot while the TRUE Test patches are on?
The official label describes the requirement to avoid excessive sweating during the testing period to maintain sufficient adhesion. Excessive moisture could lift the patches and potentially interfere with the test results.
Q: Is it normal to feel a restrictive or strange feeling from the patches on the back?
The official label notes Tape Irritation as a common adverse reaction. Clinical instructions mention that test sites may be itchy and uncomfortable, which is related to the common adverse effect of skin irritation from the tape.
Q: Is it okay to use an electric shaver to remove hair from the test site beforehand?
If excessive body hair is present at the proposed test site, the official protocol states that it should be removed with an electric shaver. The protocol includes an instruction not to use a razor, as this could irritate the skin and interfere with the test.
Q: What can cause a false-positive result in patch testing like the TRUE Test?
The official label notes that an irritant reaction may occur, which can potentially be difficult to distinguish from a true positive allergic reaction. Irritant contact dermatitis is listed as a potential adverse reaction that can complicate the interpretation of the test results.
Q: Can the test results change over time with repeat testing?
The official label states that the effect of repetitive testing with the T.R.U.E. Test is unknown. It also warns that sensitization or increased reactivity to one or more allergens may occur.
Q: Do common over-the-counter allergy pills (antihistamines) affect the TRUE Test results?
Clinical expert consensus documents indicate that oral antihistamines, such as common over-the-counter allergy pills, generally do not affect the diagnostic patch testing process. These medications are generally described as being able to be continued during the test.
