Instructions for educating patients on ROAT testing in conjunction with patch testing

Dermatology Nursing, April, 2008 by Carmen B. Gelpi, Sharon E. Jacob

Allergic contact dermatitis (ACD) is common in today's population with over 72 million people suffering with this diagnosis in 2004 (Jacob & Steele, 2006). The gold standard procedure to diagnose ACD is patch testing in which chemicals are applied to the patient and evaluated by a contact dermatitis specialist to establish the culprit cause of the patient's allergy. In the United States there are two commercially available Food and Drug Administration-indicated patch test screening tools used to evaluate patients.

Evaluating patients with a possible cosmetic or medicament allergy requires further acquaintance with using patch test substances beyond these standard trays, including the patient's own products, which are deemed potentially clinically relevant. For example, Freeman (1995) found that patch testing with the patient's corticosteroid in the commercial cream base gave a greater yield of positive results than testing with the commercial corticosteroid ointment or with the pure corticosteroid in either petrolatum or in alcohol. This being said, the diagnosis of corticosteroid allergy is often difficult on account of frequently false-negative patch test.

Patch testing is then followed by repeat open application testing (ROAT) to confirm that the putative allergen is in fact responsible for the ACD or counter a false-positive or reduce a false-negative result (a common problem with corticosteroid allergy) (Bruze, 1995; Stewart 1996). Repeated application of the suspected product to the same skin area may unmask an underlying sensitivity and prevent the patient from unwittingly using the wrong product (Curry & Warshaw, 2005). For this reason ROAT testing is an important tool to teach patients to perform in the convenience of their home. For example, patients with sensitivity to fragrances should opt to use all fragrance-free cosmetics. That being said many choose to perform ROAT testing to the cosmetic or perfumed products to determine whether sensitivity exists. We have found that providing written and demonstrational ROAT testing instructions are an effective way to educate patients on the proper performance of the test.

[FIGURE 1 OMITTED]

Instructions for Performing ROAT Testing

Patient should use water to gently cleanse the ROAT test area of the skin prior to the application of any products. The skin should not be "prepped" with alcohol or harsh soaps, and no emollients should be applied in the testing area. After showering (so as to avoid dilution), only the personal hygiene or medicament product in question should be applied to the test area. It is recommended that testing the skin with unknown chemicals not be performed. During the ROAT testing the skin should be protected from UV light (including sunlight) exposure.

One can test products intended to be left on the skin, such as lotions, creams, and topical medicaments (steroids). First, bend the arm and draw a 3 cm diameter circle on clinically normal skin 4 to 5 cm above the crease (where the lower arm does not come into contact with the upper arm) (see Figure 1). Apply a small quantity of the product (0.5-1 pea size) twice daily to the circle for 7 days. Check the circle daily for a reaction (seen as redness, scale, small bumps, or water blisters) (Hannuksela & Salo, 1986). Notify the patch test nurse if a reaction develops.

In the unlikely case of a severe cutaneous reaction, see your dermatologist for a proper evaluation. The dermatologist will likely prescribe compresses and/or a midpotency corticosteroid to the site.

References

Bruze, M. (1995). Improved management of allergic contact eczema. Nordisk Medicin, 110(3), 90-92.

Curry, E.J., & Warshaw, E.M. (2005). Benzyl alcohol allergy: Importance of patch testing with personal products. Dermatitis, 16(4), 203-208.

Freeman, S. (1995). Corticosteroid allergy. Contact Dermatitis, 33(4), 240-242.

Hannuksela, M., & Salo, H. (1986). The repeated open application test (ROAT). Contact Dermatitis, 74, 221-227.

Jacob, S.E., & Steele, T. (2006). Contact dermatitis and workforce economics. Seminars in Cutaneous Medicine and Surgery, 25, 105-109.

Stewart, L.A. (1996). Patch testing to cosmetics and topical drugs. American Journal of Contact Dermatitis, 7(1), 53-55.

Carmen B. Gelpi, MA, is Contact Dermatitis Coordinator, University of Miami, Miami, FL.

Sharon E. Jacob, MD, is an Assistant Professor of Medicine (Dermatology), University of California, San Diego, CA.