Routine diagnostic patch-testing with formaldehyde 2.0% (0.6 mg/cm2) may be an advantage compared to 1.0%

Contact dermatitis associated with preservatives: Retrospective analysis of North American Contact Dermatitis Group data, 1994 through 2016

BACKGROUND

Preservatives are often necessary components of commercial products. Large-scale North American studies on preservative allergy are limited.

OBJECTIVE

To evaluate demographics, positive patch test reactions (PPTRs), clinical relevance, and trends for preservatives tested by the North American Contact Dermatitis Group.

METHODS

We conducted a retrospective cross-sectional analysis of North American Contact Dermatitis Group patch testing results of preservatives from 1994 through 2016.

RESULTS

A total of 50,799 patients were tested; 11,338 (22.3%) had a PPTR to at least 1 preservative. The most frequent reactions were to methylisothiazolinone 0.2% aqueous (aq) (12.2%), formaldehyde 2% aq (7.8%), formaldehyde 1% aq (7.8%), quaternium-15 2% petrolatum (pet) (7.7%), and methyldibromo glutaronitrile/phenoxyethanol 2% pet (5.1%). Paraben mix 12% pet (1%), iodopropynyl butylcarbamate 0.1% pet (0.4%), benzyl alcohol 1% pet (0.3%), and phenoxyethanol 1% pet (0.2%) had the lowest PPTRs. Linear regression analysis of preservatives tested showed that only methylchloroisothiazolinone/methylisothiazolinone 0.01% aq (parameter estimate, 0.42; 95% CI, 0.17-0.66; P < .005) had a significant increase in PPTRs over time.

LIMITATIONS

Collected variables are dependent on clinical judgment. Results may be prone to referral selection bias.

CONCLUSIONS

This large North American study provides insight on preservative PPTRs and trends from 1994 through 2016.

A comparative study between the two patch test systems Finn chambers and Finn chambers AQUA

BACKGROUND

Finn Chambers AQUA (FCA) is a development of the Finn Chambers (FC) test system in which the test chambers are mounted on a moisture-resistant adhesive patch. FCA has pre-fixed filter papers. Because the use of FCA does not require any extra taping or use of separate filter papers, a change from FC to FCA chambers may be beneficial for both patients and patch test technicians.

OBJECTIVES

To investigate whether there are any differences regarding detection of contact allergy when simultaneous patch testing is performed with FC and FCA.

MATERIALS AND METHODS

Results from 434 dermatitis patients simultaneously tested with 10 allergens in both FC and FCA were evaluated.

RESULTS

There were no significant differences regarding detection of positive reactions between the two test systems. There were significantly more doubtful reactions to methylisothiazolinone, fragrance mix I and hydroperoxides of linalool when testing with FCA. We only observed significantly more doubtful reactions in FC regarding nickel(II)sulfate. Irritant reactions to formaldehyde were also significantly more common when using FCA.

CONCLUSION

The FC and FCA had good agreement in detection of positive reactions. However, the results including doubtful and irritant reactions justify further research regarding optimization of the dose.

Comparison of Nickel Sulfate 2.5% and Nickel Sulfate 5% for Detecting Nickel Contact Allergy

BACKGROUND

Nickel is among the most common contact allergens found on patch testing worldwide and, because of its ubiquitous nature in our environment, often has important implications for allergen avoidance strategies. In both North America and Europe, nickel positivity is found in approximately 20% of patients who undergo patch testing. Whereas in North America, nickel sulfate is typically tested at a concentration of 2.5%, in Europe, it is tested at a 5% concentration.

OBJECTIVE

The primary objective was to assess the differences in patch test positivity to nickel sulfate 2.5% and 5%.

METHODS

We investigated 205 consecutive patients between September 2017 and February 2018 who were tested to nickel sulfate at concentrations of both 2.5% and 5%.

RESULTS

Among the 205 patients tested, 33% were positive (+, ++, or +++) to at least 1 concentration of nickel sulfate, 20% were positive to nickel sulfate 2.5%, and 31% were positive to nickel sulfate 5% (χ1(N = 205) = 16.1, P = 0.0001). Patients were 6.5 times more likely to have a positive reaction to nickel sulfate 5% than 2.5% (odds ratio 95% confidence interval, 2.3-25.6).

CONCLUSIONS

Given our findings, we propose an additional evaluation of nickel sulfate 5% as a standard allergen for patch testing in North America.

Hand eczema and occupational contact allergies in healthcare workers with a focus on rubber additives

BACKGROUND

Hand eczema (HE) in healthcare workers (HCWs) is common. Besides wet work, healthcare work also implies exposure to contact allergens.

OBJECTIVES

To assess HE and contact allergy related to occupational exposures in HCWs.

METHODS

In a cross-sectional study, 311 HCWs with HE within the preceding 12 months and a control group of 114 HCWs without HE were investigated with the baseline series and a special patch test series based on substances found in the gloves, soaps, alcoholic hand disinfectants and hand creams provided at the hospitals.

RESULTS

Contact allergy to rubber additives was significantly more common in HCWs with HE (6%) than in HCWs without HE (1%, P = .02). The corresponding percentages for fragrances were 11% and 3%, respectively (P = .004). Occupational HE was found in 193 of 311 (62%) HCWs. Of these, 22 of 193 (11%) had occupational allergic contact dermatitis, including 17 with glove-related rubber contact allergy. Contact allergy to diphenylguanidine was as common as contact allergy to thiurams. Occupational contact allergy to rubber additives was significantly associated with sick-leave related to HE.

CONCLUSION

Contact allergy to rubber additives in medical gloves is the most common cause of occupational allergic contact dermatitis in HCWs. Aimed patch testing with relevant rubber additives is mandatory when HE in HCWs is investigated.

Diagnostic utility of skin autofluorescence when patch test results are doubtful

BACKGROUND

The standard diagnostic test for allergic contact dermatitis is the patch test, which can also be used to identify irritant contact dermatitis. Doubtful reactions (?+) can be often clinically relevant to individuals and can require additional tests.

OBJECTIVES

The purpose of this study was to examine whether autofluorescence (AF) measurements in patients with doubtful reactions are helpful in diagnosing contact dermatitis.

METHODS

Patients with a history of contact dermatitis were patch tested on the upper back for 48-hours of occlusion using aqueous solutions of 5% sodium lauryl sulfate. Reaction intensity was scored, and AF was measured on reactive lesions and non-lesions. Three dermatologists classified the results as positive or negative using the fluorescence photographs of patients with a doubtful reaction.

RESULTS

Among doubtful reactions, the R/G% values were significantly higher in the AF- based positive group than in the negative group (P = .0086). On the other hand, the heterogeneity values of R, G, and B (HR, HG, HB) were significantly lower in the AF-based positive group (P = .0026, .0046, .0004 respectively).

CONCLUSIONS

Measuring AF along with the clinical readings can help confirm doubtful patch test reactions.

Skincare products containing low concentrations of formaldehyde detected by the chromotropic acid method cannot be safely used in formaldehyde-allergic patients

BACKGROUND

Formaldehyde is a well-known contact sensitizer. Formaldehyde releasers are widely used preservatives in skincare products. It has been found that formaldehyde at concentrations allowed by the European Cosmetics Directive can cause allergic contact dermatitis. However, we still lack information on whether formaldehyde at low concentrations affects dermatitis in formaldehyde-allergic individuals.

OBJECTIVES

To study the effects of low concentrations of formaldehyde on irritant contact dermatitis in formaldehyde-allergic individuals.

METHODS

Fifteen formaldehyde-allergic individuals and a control group of 12 individuals without contact allergy to formaldehyde and formaldehyde releasers were included in the study. The individuals performed the repeated open application test (ROAT) during 4 weeks with four different moisturizers releasing formaldehyde in concentrations that had been determined as > 40, 20-40, 2·5-10 and 0 p.p.m. by the chromotropic acid (CA) spot test. Dimethyloldimethylhydantoin was used as a formaldehyde releaser in the moisturizers. The ROAT was performed on areas of experimentally induced sodium lauryl sulfate dermatitis. The study was double blind, controlled and randomized.

RESULTS

Nine of the 15 formaldehyde-allergic individuals had reappearance or worsening of dermatitis on the areas that were treated with moisturizers containing formaldehyde. No such reactions were observed in the control group (P < 0·001) or for the moisturizers without formaldehyde in the formaldehyde-allergic individuals (P < 0·001).

CONCLUSIONS

Our results demonstrate that the low concentrations of formaldehyde often found in skincare products by the CA method are sufficient to worsen an existing dermatitis in formaldehyde-allergic individuals.