Introduction: The opinions about the occurrence of the contact allergy and psoriasis differ.
Aims: To assess the frequency of contact allergy among patients with psoriasis.
Material and methods: Meta-analysis of clinical-epidemiological publications concerning the frequency of contact allergy among psoriasis patients. Pooled frequencies with confidence intervals (95%CI) were presented in comparison to estimates of frequencies of contact allergy in the general population (Schäfer et al. 2001).
Results: The pooled frequency of contact allergy among patients with psoriasis in all analyzed publications was 21.6% (95%CI 18.8-24.5%). Most patients were allergic to nickel (8.8%; 95%CI 6.6-10.8%; frequency in the general population according to Schafer: 9.9%). Other haptens that commonly sensitized psoriasis patients were: diaminodiphenylmethane (3.3%; 95%CI 1.3-5.3%; estimates for general population not available), fragrance mix (3.3%; 95%CI 1.5-3.9%; Schäfer: 11.4%), thiomersal (2.6%; 95%CI 1.0-4.0%; 3.2%), neomycin (2.4%; 95%CI 1.2-3.7%; 1.3%), paraphenylenediamine (2.5%; 95%CI 1.1-3.4%; 3.2%), chromium (2.6%; 95%CI 0.9-3.2%; 0.8%). Among patients with psoriasis, contact allergy to topical drugs used for treating this disease also occurs quite often: 4.7% of all patients with psoriasis were allergic to dithranol, 5.2% to coal tar and 11.8 to wood tar mix.
Conclusions: The frequency of contact allergy among psoriasis patients is similar to that in the general population. Rare allergy to fragrance mix among psoriasis patients is an exception, which could result from a more cautious use of perfumes in this group. The relatively high frequency of contact allergy to antipsoriatic drugs is of particular relevance taking into consideration the long-lasting topical treatment.
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Document created: 17 October 2008, last updated: 4 July 2010.