Multiyear Group and Medical Center Patch Test Frequency Data: Confounding Variables

Trends in the Prevalence of Methylchloroisothiazolinone/Methylisothiazolinone Contact Allergy in North America and Europe

Importance

The common use of isothiazolinones as preservatives is a global cause of allergic contact dermatitis. Differences in allowable concentrations of methylisothiazolinone (MI) exist in Europe, Canada, and the US.

Objective

To compare the prevalence of positive patch test reactions to the methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) combination and MI alone in North America and Europe from 2009 to 2018.

Design, Setting, and Participants

This retrospective analysis of North American Contact Dermatitis Group, European Surveillance System on Contact Allergies (ESSCA), and the Information Network of Departments of Dermatology (IVDK) databases included data from patients presenting for patch testing at referral patch test clinics in North America and Europe.

Exposures

Patch tests to MCI/MI and MI.

Main Outcomes and Measures

Prevalence of allergic contact dermatitis to MCI/MI and MI.

Results

From 2009 to 2018, participating sites in North America and Europe patch tested a total of 226 161 individuals to MCI/MI and 118 779 to MI. In Europe, positivity to MCI/MI peaked during 2013 and 2014 at 7.6% (ESSCA) and 5.4% (IVDK) before decreasing to 4.4% (ESSCA) and 3.2% (IVDK) during 2017 and 2018. Positive reactions to MI were 5.5% (ESSCA) and 3.4% (IVDK) during 2017 and 2018. In North America, the frequency of positivity to MCI/MI increased steadily through the study period, reaching 10.8% for MCI/MI during 2017 and 2018. Positive reactions to MI were 15.0% during 2017 and 2018.

Conclusions and Relevance

The study results suggest that in contrast to the continued increase in North America, isothiazolinone allergy is decreasing in Europe. This trend may coincide with earlier and more stringent government regulation of MI in Europe.

Long-Term North American Trend in Patch Test Reactions: A 32-Year Statistical Overview (1984-2016)

Background: Allergic contact dermatitis (ACD) remains a public health issue worldwide, despite regulations intended to minimize sensitization. With up-to-date knowledge about which chemicals continue to have high allergenicity, the government/industry can refocus their efforts to be most effective. Objective: We reviewed updated data showing common allergens that elicit ACD to determine the progress in reducing sensitization to inform public health policy, government regulation, and industry standards. Methods: We compiled data from the North American Contact Dermatitis Group showing patch test results from 1984 to 2016 for 153 compounds. Using these data, we analyzed the trends over time of positive test reactions to determine whether they are increasing or decreasing. Results: Of the 47 compounds with sufficient data to analyze, 23 had a decreasing proportion of positive patch test results over the whole period. An additional 5 had a decreasing proportion over a shorter period. Finally, 4 had an increasing proportion over any period: compositae mix, methylchloroisothiazolinone/methylisothiazolinone, nickel sulfate, and thimerosal mix. Conclusions: The data strongly indicate decreasing and increasing frequency trends and challenge us to seek explanations, which are not yet clear. It is hoped that these data can be valuable in informing public health policy, government, and industry.

Long-Term North American Trend in Patch Test Reactions: A 32-Year Statistical Overview (1984-2016)

BACKGROUND

Allergic contact dermatitis (ACD) remains a public health issue worldwide, despite regulations intended to minimize sensitization. With up-to-date knowledge about which chemicals continue to have high allergenicity, the government/industry can refocus their efforts to be most effective.

OBJECTIVE

We reviewed updated data showing common allergens that elicit ACD to determine the progress in reducing sensitization to inform public health policy, government regulation, and industry standards.

METHODS

We compiled data from the North American Contact Dermatitis Group showing patch test results from 1984 to 2016 for 153 compounds. Using these data, we analyzed the trends over time of positive test reactions to determine whether they are increasing or decreasing.

RESULTS

Of the 47 compounds with sufficient data to analyze, 23 had a decreasing proportion of positive patch test results over the whole period. An additional 5 had a decreasing proportion over a shorter period. Finally, 4 had an increasing proportion over any period: compositae mix, methylchloroisothiazolinone/methylisothiazolinone, nickel sulfate, and thimerosal mix.

CONCLUSIONS

The data strongly indicate decreasing and increasing frequency trends and challenge us to seek explanations, which are not yet clear. It is hoped that these data can be valuable in informing public health policy, government, and industry.