Contact urticaria: Frequency, elicitors and cofactors in three cohorts (Information Network of Departments of Dermatology; Network of Anaphylaxis; and Department of Dermatology, University Hospital Erlangen, Germany).

Background: Contact urticaria (CU) is an infrequent, mostly occupational disease that may be life-threatening (CU syndrome stage 4).
Objectives: To identify the current frequency, elicitors and cofactors of CU.
Patients: Three cohorts were retrospectively analysed for CU: (a) patients from the Information Network of Departments of Dermatology (IVDK) database (2000-2014; n = 159 947); (b) patients from an allergy unit (Department of Dermatology, University Hospital Erlangen, 2000-2015; n = 4741); and (c) patients from the Anaphylaxis Registry (2007-2015: 6365 reported cases, including 2473 patients with Ring and Messmer grade III-IV reactions) for severe cases with skin/mucosal manifestations occurring at the workplace vs cases not occurring at the workplace (n = 68 vs n = 1821).
Results: Four hundred and forty-eight CU patients (0.28%) were diagnosed in the IVDK cohort, and 16 (0.34%) (10 of immunological aetiology, and 6 of non-immunological aetiology) in the Erlangen cohort. The most frequent elicitors in the IVDK cohort were cosmetics, creams, sun protection agents (although these were less frequent in CU patients than in controls without CU; 26.8% vs 35.6%, P < .0001), and gloves (significantly more frequent in CU patients than in controls; 18.1% vs 6.5%, P < .0001). The most frequent elicitors in the Erlangen cohort were natural rubber latex and sorbic acid. Among the MOAHLFA index characteristics, in both cohorts occupational disease was more common in CU patients than in patients without CU. CU was significantly associated with allergic rhinitis and allergic asthma. Wet work was a relevant cofactor. In the Anaphylaxis Registry, 19 cases (0.3%) were identified with severe reactions including skin symptoms at the workplace linked to common occupational elicitors.
Conclusions: CU is a rare occupational skin manifestation with a frequency of <0.4% in the examined patients; it may, however, progress to anaphylaxis. Preventive measures are important, and should take into account the identified elicitors and cofactors.
(© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)