Strip patch test vs. conventional patch test: investigation of dose-dependent test sensitivities in nickel- and chromium-sensitive subjects.

BACKGROUND

Tape stripping the skin prior to patch testing (strip patch test, SPT) may enhance percutaneous penetration of test substances and increase skin reactivity to test substances.

OBJECTIVE

To evaluate the test sensitivity of SPT in compliance with our recently presented practical method vs. conventional patch test (PT) in nickel- and dichromate-sensitive subjects.

METHODS

Thirty subjects participated in the prospective, randomized, controlled, investigator-blind study. Serial dilution tests of nickel sulphate (10,000-50 ppm aq.) and potassium dichromate (1000-5 ppm aq.) were used. Tests were applied in duplicate to both sides of the upper back of the subject, where one, randomly chosen side was tape stripped.

RESULTS

According to the estimated test sensitivities, SPT is more sensitive than PT in nickel- and dichromate-sensitive subjects, regardless of the interindividual different numbers of tape strips. The superiority of the SPT grows with diminishing concentrations of the allergens.

CONCLUSION

Test sensitivity of SPT vs. PT is increased. If no positive results are obtained by PT, the SPT could help to detect hidden allergens in case of weak sensitization or low concentration and poor percutaneous penetration of the test substances.