Alternatives for the 2007 North American Contact Dermatitis Group (NACDG) Standard Screening Tray
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Contact Allergy: Alternatives for the 2007 North American Contact Dermatitis Group (NACDG) Standard Screening Tray Andrew Scheman, MD, Sharon Jacob, MD, Matt Zirwas, MD, Erin Warshaw, MD, Susan Nedorost, MD, Rajani Katta, MD, Jeremy Cook, BA, and Mari Paz Castanedo-Tardan, MD Introduction Most primary care physicians see a large number of patients each year with eczematous skin diseases. Although many of these patients have atopic eczema, another extremely common cause of eczema is contact allergy. This subgroup of eczema patients is notably resistant to treatment unless the causative allergens can be identified and eliminated. It is estimated that allergic contact dermatitis (ACD) to topical products alone occurs in 1% to 3% of the general population.1,2 Unlike respiratory and food allergies, ACD is not histamine-mediated but is instead a T-cell- mediated delayed-type hypersensitivity reaction.3 The basic pathophysi- ologic process behind ACD is primary skin contact with an allergenic chemical which triggers an immune cascade and results in an eczematous reaction at the site of contact. On first exposure to low molecular weight chemical substances (haptens Ͻ500 Da), there is generally no skin reaction.4 During this first phase, these haptens enter the epidermis and are recognized by antigen present- ing cells, which in turn create signals that transform naïve T cells into memory T cells, a process which typically takes 5 to 25 days.4 Subsequent reactions due to “challenge” with the same chemical sub- stance generally occur between 24 and 48 hours after exposure; however, reports of reactions occurring as early as 8 hours after exposure and as long as 1 week after exposure are not uncommon.4 Dis Mon 2008;54:7-156 0011-5029/2008 $34.00 ϩ 0 doi:10.1016/j.disamonth.2007.10.002 DM, January/February 2008 7 ACD is diagnosed by a procedure called patch testing. Many derma- tologists obtain significant training in skin patch testing during their residencies. In addition, some physicians in other fields (such as allergists and occupational medicine doctors) may also have some training with this procedure. Comprehensive patch testing is performed by placing stan- dardized concentrations of contact allergens on either aluminum (Finn) or plastic (IQ) chambers and attaching these to the skin of the back with hypoallergenic paper tape. A commercially available screening tool [The Thin-Layer Rapid Use Epicutaneous Test (TRUE) Allerderm Laborato- ries/Smarthealth, Phoenix, AZ] is also available in the U.S. This FDA- approved patch test consists of 23 common contact allergens and mixes.9 The TRUE test is a pre-prepared peel-off system which can be easily performed in any office setting. Unfortunately, recent studies have shown that the TRUE test only fully diagnoses approximately 25.5% of all cases of contact allergy10 and is more likely to give false-negative reactions than when using Finn chambers.9,11 With both comprehensive and TRUE testing, patches are typically left in place for 48 hours and then removed.5 Patch test readings in the U.S. are most commonly done at 72 and 96 hours after applications of the allergens.6 Some physicians also do a reading at 1 week after applica- tion.7 Patch reactions are graded 1ϩ (erythema), 2ϩ (papules or edema in less than half of the test site), or 3ϩ (papules or edema in greater than half of the patch test site, or confluent vesiculobullous reactions).8 At 96 hours, a final patch test reading will be done and the results are then explained to the patient. The information which is passed to the patient during the final visit is of paramount importance. Although performing a patch test procedure is not technically difficult, the interpretation of the patch test results and the education of the patch test patient are much more difficult. A patch testing specialist must know the significance of each test material, where the material is found, and, most importantly, be able to educate the patient on how to avoid contact with each test substance. Over the past 50 years, more and more diverse chemicals have entered our daily existence. For example, there are over 5000 registered cosmetic ingredients which are used in skin, hair, and cosmetic products in the U.S. today.12 Therefore, comprehensive contact allergy testing has become much more complicated over the past several decades. A survey from 1997 found that 83% of dermatologists in the U.S. perform patch testing and 74% of these physicians use the TRUE test.6 Approximately 83% of dermatologists who do patch testing indicate that they perform testing on fewer than 5 patients per month.6 Therefore, it is clear that most 8 DM, January/February 2008 dermatologists perform very limited patch testing on small numbers of patients. A small number of dermatologists are dedicated experts in the practice of comprehensive contact allergy testing. Typically, these physicians purchase contact allergy testing materials from overseas and have multiple testing materials covering a wide range of potential chemicals which are likely to be experienced in the home or in a variety of work settings. Typically, contact dermatitis specialists will spend considerable time investigating the history of the patient and individualizing patch testing to customize to the topical exposure experienced by each patient. Correctly selecting the allergens to use in testing is vital, as the only known cure for ACD is avoidance of the offending allergen. Because avoidance generally requires the substitution of safe alternatives, it is essential that the patch testing expert have a sound working knowledge of potential product alternatives which may be selected to exclude the patient’s known allergens. In 2004, the American Academy of Dermatology and Society of Investigative Dermatology studied the burden of skin diseases and found that 72 million Americans that year suffered with ACD. Primary care physicians are on the frontline encountering this large number of patients every year. Whereas many of these patients will respond readily to standard treatments, there will be others that demonstrate recalcitrant dermatitis. Many authors have recommended that patch testing be considered in all patients with recalcitrant eczema. It has been estimated that approximately 16% of all chronic eczema patients would benefit from contact allergy patch testing.13 In 1979, it was estimated that there were 5.7 million medical office visits made in the U.S. for evaluation of dermatitis.14 Over the past 28 years, this number has likely increased considerably. Therefore, it would be a conservative estimate to state that approximately 1 million patients each year in the U.S. would benefit from patch testing. ACD can follow certain distributions suggestive of contact with a particular substance. For instance, eczema limited to the armpits may suggest contact allergy to an ingredient in antiperspirant or deodorant, whereas eczema limited to the scalp may suggest contact allergy to hair products, such as shampoos, conditioning agents, or dyes. With an eczema on the soles of the feet, a contact allergy to a shoe insole or adhesive material should be considered, especially if there is sparing of the instep (where contact is not made with the shoe component). For all of these types of patients, correct identification of the culprit chemical by DM, January/February 2008 9 the patch testing specialist may lead to complete elimination of severe, debilitating eczema. In this article, the American Contact Alternative Group (Members: A. Scheman, M. Zirwas, S. Nedorost, S. Jacob, R. Katta, and E. Warshaw) will discuss the most common substances known to cause ACD, where these substances are found, and alternative products which can be used by individuals allergic to each of these substances. The allergens discussed in this article are those found on the current 2007 North American Contact Dermatitis Group (NACDG) standard tray. NACDG refers to a group of 13 contact dermatitis specialists in Canada and the United States who regularly research and compile data on the frequency of contact allergy to various substances.15 The standard screening tray is designed as a base panel to investigate the most common causes of contact allergy; however, comprehensive contact allergy testing centers generally supple- ment the standard screen with a number of selected chemical allergens from a large battery of site- or type-specific trays (eg: fragrances, shoe components, botanicals, vehicles, and cosmetics). It is the opinion of the authors of this article that primary care physicians play a large role in the identification and successful treatment of patients experiencing contact allergy. And because there are a large number of patients suffering needlessly from potentially debilitating skin dermatitis who, given appropriate testing, counseling, and alternatives, could live dermatitis-free, this tool has been developed. We recognize that appropriate patch testing is critical. However, without appropriate edu- cation on avoidance of substances and recommendation of alternative allergen-free alternatives, avoidance compliance, and thus positive out- comes, will be low. Although much of this education can be done at the time of testing, many of these allergens are ubiquitous, and it is easy for the patient to have flare-ups due to unexpected contact with allergenic substances. Therefore, to obtain optimal success in treating these patients, it is necessary for them to receive reinforced education regarding avoidance of the substances to which they are allergic. In this article, we hope to familiarize primary care physicians with the allergens found on the NACDG standard tray, their significance, and alternatives which will allow the patient to avoid each substance. In this way, we hope to encourage primary care physicians to recognize ACD and to know when to refer patients for comprehensive testing and to help them play a significant role in counseling their patients on an ongoing basis after contact allergy has been identified.