In a multicentre study of the German
Contact Dermatitis Research Group,
sodium lauryl sulfate (SLS) 0.25% and 0.5% aq. has been added to routine
allergen patch tests to assess its properties as a convenient diagnostic
indicator of individual susceptibility to irritation at the time of patch testing. Previous studies indicated that
irritant SLS reactivity may be related to individual factors such as age and sex. As these factors are, in turn, among the important predictors of contact
allergy to many
allergens, e.g. summarized in the 'MOAHLFA index', the impact of the MOAHLFA factors on
irritant SLS patch test reactivity, and thus a potential for confounding, was assessed in the 5971 participating patients. As a result of 2 logistic regression analyses with an
irritant reaction to 0.25% and 0.5% SLS, respectively, as outcome, male sex was identified as a relatively weak but significant risk factor (OR 1.38), while age 40 years or older was an even weaker risk factor (OR 1.22 and 1.15, respectively). Upon detailed analysis, no clear age gradient could, however, be identified. 1-day exposure time almost halved the odds of an
irritant SLS reaction. In conclusion, this type of SLS patch test can be regarded as robust, indicating individual irritability relatively independent from the individual factors analysed here.