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Notes: Background  There is evidence that a higher skin susceptibility may induce nonspecific erythematous or weak positive reactions to contact allergens in patch testing.Objectives  To evaluate whether simultaneous application of sodium lauryl sulphate (SLS) along with diagnostic patch tests with contact allergens can provide information regarding skin irritability which may help to discriminate allergic from nonspecific irritant reactions to contact allergens.Methods  Between July 2001 and June 2003, this prospective study collected patch test data of 5971 patients from 19 centres in Germany and Austria in the Information Network of Departments of Dermatology (IVDK). In addition to contact allergens (standard series and eight known ‘problematic’ allergens with a low reaction index and a high positivity ratio: 1,3-diphenylguanidine, amerchol L-101, benzalkonium chloride, benzoyl peroxide, cocamidopropyl betaine, octyl gallate, phenyl mercuric acetate and propylene glycol), patches with SLS 0·5% and 0·25% aq. were applied. Reactions to the allergens and to SLS were analysed at the IVDK data centre. The association between an erythematous or positive reaction to a certain allergen and an irritant reaction to SLS was assessed with logistic regression analysis, at the same time controlling for the influence of age and sex.Results  Of the 29 allergens of the standard series, 23 and 21 gave a higher percentage of nonspecific erythematous reactions in patients with an irritant reaction to 0·25% and 0·5% SLS, respectively, in comparison with SLS-negative patients. All eight ‘problematic’ allergens gave an increased percentage of nonspecific erythematous reactions. Similarly, 22 and 21 allergens of the standard series gave a higher percentage of positive allergic reactions in patients with an irritant reaction to 0·25% and 0·5% SLS, respectively, and seven of the eight ‘problematic’ allergens gave a higher percentage of positive allergic rections (exception: octyl gallate). For most allergens, the markers of skin reaction (reaction index and positivity ratio) were worse in SLS-positive patients. Differences were more pronounced when testing with SLS 0·25% than with SLS 0·5%.Conclusions  Because there is a convincing association between skin irritability (evaluated by SLS test) and the degree of skin reaction to contact allergens, the SLS test may help in deciding whether a doubtful erythematous or weakly ‘positive’ skin reaction should be interpreted as allergic or irritant.

Notes: Background:  Previous research indicates that positive patch tests to nickel (II) sulphate, cobalt (II) chloride and potassium dichromate commonly occur together.Methods:  To further examine the relationship between nickel, cobalt, chromate, and the factors that may potentially be related to concurrent sensitizations to two or all three metal allergens, data from the Information Network of Dermatology Departments (IVDK, ) have been investigated.Results:  Women had a higher conditional odds of concurrent nickel–cobalt (OR = 6.80; 95% CI: 5.65–8.19) and nickel–chromate (OR = 2.13; 95% CI: 1.67–2.72) reactions than men. Construction workers had a significantly higher odds of cobalt–chromate reactions (OR = 13.89; 95% CI: 10.36–18.64), while the odds of isolated cobalt allergy was only 0.92 (95% CI: 0.48–1.74). Patients with underlying atopic eczema/dermatitis syndrome had a 40–90% higher chance of any positive outcome, which involved chromate. Polysensitization, defined as the number of positive reactions to standard series substances other than nickel, cobalt, and chromate, was also significantly associated with the concurrent reactions; moreover, steady and significant effect gradients were noted.Conclusions:  This research confirms the occupational nature of cobalt–chromate concurrent reactions, in particular, in construction workers. Polysensitization, which is considered to represent susceptibility to delayed-hypersensitivity in general, is also associated with the concurrent reactions to the metals. Hence, not only coupled exposure, but also individual susceptibility may be responsible for concurrent reactions to metals in man.

Notes: There is conflicting evidence concerning seasonal variability of patch test results and no evidence concerning the influence of season on weak-positive, possibly false-positive, irritant reactions, which was analysed in the present study. Data collected in the German Information Network of Departments of Dermatology (IVDK) 1992 to 1997 were combined with external environmental data on temperature and absolute humidity in Germany, and bivariate as well as logistic regression analyses performed concerning the association between reactivity to selected allergens and air temperature and absolute humidity on the respective days of patch testing. Between 39,239 and 41,629 patients had been tested with the 4 allergens considered here. Only formaldehyde exhibited a distinct increase in questionable or irritant as well as weak-positive reactions associated with dry, cold weather. Methylchloroisothiazolinone/methylisothiazolinone and lanolin alcohol showed only a weak, and epoxy resin no, association with climatic conditions. The results indicate that weak-positive reactions, at least to formaldehyde as a prototype of an allergen which is at the same time a marginal irritant, may sometimes be irritant rather than allergic. Patients showing these should be re-tested to improve the poor reproducibilty observed with this allergen.

Notes: Contact allergy to oil of turpentine was reported to have become rare. However, the evaluation of standardized data of 45,005 patients tested 1992–1997 in 30 Dermatological Centers associated with the German-Austrian Information Network of Departments of Dermatology (IVDK) showed an increase in positive patch test reactions to turpentine from 0.5% during the years 1992–1995, up to 1.7% in 1996 and 3.1% in 1997. In particular, 17,347 patients tested in 1996–1997 were evaluated in detail by comparing 431 individuals with positive patch test reactions with the rest of the group found negative to turpentine. Using the so-called MOAHLFA index, the following characteristics were shown. Turpentine allergy (a) was found to be significantly less frequent in men and in patients with occupational dermatitis, (b) showed no difference in its association with atopic dermatitis, (c) patients with turpentine allergy had significantly less symptoms of the hands, more symptoms of the legs or in the face and (d) were significantly more often aged over 60 years. Also, patients sensitized to turpentine had increased rates of additional sensitizations. The definite reason for the increase in turpentine sensitization in the population tested here is not clear. Therefore, a detailed exposure analysis is necessary; the new increase in turpentine allergies may be due to popular topical remedies or household chemicals.

Notes: We investigated whether patients with contact allergy differed from non-contact-allergic, non-atopic controls with regard to genotype and phenotype of the polymorphic enzyme N-acetyltransferase 2 (NAT2). 55 contact-allergic patients recruited from the Information Network of Departments of Dermatology (IVDK) were compared to 85 controls from among local health care personnel. NAT2 activity was calculated from HPLC analysis of the ratio of the caffeine metabolites 5-acetylamino-6-formylamino-3-methyluracil (AFMU) and 1-methylxanthine (1MX) in the urine. NAT2 genotype was determined by polymerase chain reaction (PCR). A statistically significantly increased proportion of rapid acetylators was found in contact-allergic patients. This may have 2 possible implications: acetylation may enhance contact sensitization; or NAT2 status may be a genetic marker for contact sensitizability.

Notes: Sensitization rates to contact allergens vary between centers and are influenced by sex and age. Eliminating the latter 2 factors by standardization of data by age and sex, the present analysis address possible differences between centers remaining after elimination of these confounders, and analyzes other factors which might influence rates, e.g. the MOAHL index. Overall standardized rates were well within the range reported in previous studies and may be regarded as representing the rates of the “patch test population” in Central Europe (e.g. nickel sulfate 12.9%, fragrance mix 10.5″. balsam of Peru 7.3%. thimerosal 5.6%). For this analysis, data of those departments which contributed more than 2000 patients or of those with extreme proportion concerning sex, age and occupational cases were selected. Patients from these 10 departments differed considerably will regard to the items of the MOAHL index and with regard to standardized rates. The items of the MOAHL index proved to be suitable for describing different patch test populations and for explaining some differences between centers. Only ‘atopic dermatitis’ seems to have little influence on (standardized) rates. Face dermatitis is not yet represented in the MOAHL index, but should be included, together with age 〉 40 years, in an extended index (acronym: MOAHLFA). Regional allergen exposure (with striking differences between East Germany, West Germany and to a lesser extent Austria) seems to have a great influence on the sensitization pattern observed in a department. In addition, sociological factors may influence sensitization rates, which is exemplified by high rates of nickel allergy in a socially delined subgroup. Future studies should focus on these factors, as well as on factors concerning patch test practices and quality control.

Notes: Background  Iodopropynyl butylcarbamate (IPBC) is a new preservative in medical and cosmetic leave-on products. Although cases of allergic contact dermatitis to IPBC have been reported, it is not known whether the usual test concentration of 0·1% is appropriate for screening tests with IPBC.Objectives  To determine the concentration of IPBC that should be used in screening patch tests.Methods  An analysis was made of data filed by 26 centres of dermatology on patch tests performed with one or two concentrations of IPBC (0·1%, 0·2%, 0·3% or 0·5%) in 8106 unselected patients. Criteria used to determine the best test concentration of IPBC were the reaction index, the positivity ratio, the rate of crescendo reactions, and the relations between IPBC reactions and the MOAHLFA index irritant reactions to sodium lauryl sulphate (SLS), and allergic reactions to other contact allergens including preservatives.Results  IPBC 0·1%, 0·2%, 0·3% and 0·5% yielded 0·5%, 0·8%, 1·3% and 1·7% positive reactions, but this increase was accompanied by an even greater increase in doubtful and irritant reactions. These figures and the other criteria examined suggested the range of suitable test concentrations of IPBC to lie between 0·2% and 0·3%. A detailed analysis of MOAHLFA indices and of associations between reactions to IPBC and reactions to other allergens and to SLS showed that most of the positive reactions to IPBC 0·2% can be assumed to be allergic ones and that with IPBC 0·2% fewer false-positive reactions can be expected than with IPBC 0·3%.Conclusions  Patch testing with IPBC 0·2% is suggested for patients with eczema possibly related to preservatives.

Notes: Periorbital dermatitis is common and can be due to the external use of ophthalmic drugs. We evaluated patch test results of the Information Network of the Departments of Dermatology. During a 5-year period (1995–99), of a total 49 256 patch-tested patients, 1053 (2.1%) were eventually diagnosed as allergic periorbital contact dermatitis (APD) and 588 (1.2%) as non-allergic periorbital dermatitis (NAPD). Patient characteristics between APD, NAPD and other cases (OCs) differed with respect to sex (19.7% male in both periorbital groups versus 36.3% in OCs), atopic dermatitis (10.4% in APD versus 60.2% in NAPD versus 16.9% in OCs) and age, APD being substantially more often (68.2%) aged 40 and above than NAPD (52.6%). Several of the top allergens in OCs [such as fragrance mix, Myroxylon pereirae resin (balsam of Peru), lanolin alcohol and potassium dichromate] caused significantly fewer positive test reactions in both periorbital groups. In contrast, thimerosal, phenylmercuric acetate, sodium disulfite, gentamicin sulfate, phenylephrine hydrochloride and benzalkonium chloride tested positively significantly more often in APD but not in NAPD, verifying them as true ophthalmic allergens. Finally, in 42 cases (4%) of APD patients, additional allergens were identified by testing of the patients' own substances (mostly β-blockers, oxybuprocaine and dexpanthenol), supporting the necessity of testing with ophthalmic drugs as is where individual substances are not readily available.

Notes: Several contact allergens are tested at concentrations which might cause irritant reactions. In this study we investigated whether the reactivity to a standard irritant is useful in identifying subjects with hyperreactive skin yielding a higher rate of doubtful or irritant reactions. Sodium lauryl sulfate (SLS) 0.5% (aqua) was tested in addition to the standard series routinely for 5 years in the Department of Dermatology, Dortmund. For data analysis, we compared reactions at D3 to the standard series, the vehicle/emulsifier and preservative series and benzoyl peroxide to the reactions obtained with SLS. Proportions were standardized for age and sex. The association between reactivity to a certain allergen and SLS reactivity as a dichotomous outcome, controlled for age and sex as potential confounders, was assessed with logistic regression analysis. Results showed that of the 1600 tested patients, 668 (41.8%) had an irritant reaction to SLS which exceeded 2 + in only 41 patients. Seasonal variation was statistically significant, showing reduced SLS reactivity in summer vs. winter. Patients with irritant reactions to SLS showed significantly more erythematous reactions to the following 10 allergens of the standard series: fragrance mix, cobalt chloride, balsam of Peru (Myroxylon pereirae), lanolin alcohol, 4-phenylenediamine base (PPD), propolis, formaldehyde, N-isopropyl-N′-phenyl-p-phenylenediamine (IPPD), benzocaine, and 4-tert-butylphenol-formaldehyde resin. No significant differences regarding strong positive allergic reactions were observed. Concerning other allergens, significantly more erythematous reactions were observed in SLS-reactive patients to benzoyl peroxide, octyl gallate, cocamidopropyl betaine, Amerchol L-101, tert-butylhydroquinone, and triethanolamine. In the SLS-reactive group of patients, the reaction index was negative for 10 allergens of the standard series compared to only 5 in the SLS non-responder group. For the first time, this study, based on a large data pool, revealed a significant association between reactivity to the irritant SLS and erythematous reactions to certain allergens. With SLS as a marker for hyperreactive skin at hand, some of these reactions can now be classified as irritant more confidently, particularly if there is no history of exposure to the allergen.

Notes: To quantify the independent impact of potential risk factors for nickel contact allergy (NCA), a multifactorial Poisson regression analysis of standardized anamnestic and patch test data (with nickel sulfate, 5% in petrolatum) was performed, comprising 74 940 patients assessed in the 33 German and Austrian contact dermatitis units of the Information Network of Departments of Dermatology (IVDK) between 1992 and 2000. NCA was observed in 15.5% patients. Female sex was the strongest risk factor (prevalence ratio 3.74, 95% CI: 3.51–3.98). Risk increased monotonically and significantly with decreasing age. Atopic dermatitis was not a risk factor. The year of patch test had no influence on NCA risk. Significant variation of risk between occupations was observed. In conclusion, our multifactorial analysis was able to quantify the impact of established risk factors and additionally address other, e.g. occupational, factors yet unidentified.