Supplementary Material for: Risk of Atopic Disorders in Patients with Chronic Urticaria: A Systematic Review and Meta-Analysis

Background: Chronic urticaria (CU) has been associated with several systemic and autoimmune disorders. The association with atopic disorders is however controversial. The objective of this study was to perform a systematic review and meta-analysis to assess the association between CU and the atopic disorders: atopic dermatitis (AD), asthma, and allergic rhinoconjunctivitis (ARC). Methods: Search hits from PubMed, Embase, Cochrane Library, and Web of Science were systematically reviewed. English papers from 2000 to present, containing original data of the association (prevalence, incidence, or risk) between CU and any atopic disorder(s), were included. Pooled point prevalence and OR with 95% confidence intervals were calculated with a random effects model. Results: A total of 8,108 search hits were screened and reviewed. Thirty-eight studies met all inclusion criteria. The estimated pooled point prevalence of AD, asthma, and ARC in CU was 7% (5–11%, I2 = 99%), 12% (9–15%, I2 = 100%), and 22% (16–29%, I2 = 100%), respectively. Pooled ORs were estimated to 2.75 (2.05–3.68, I2 = 94%) for AD, 1.87 (1.01–3.45, I2 = 100%) for asthma, and 2.94 (1.84–4.68, I2 = 100%) for ARC. Conclusion: Pooled point prevalences of atopic disorders in CU were comparable to the general population. However, studies that compared prevalences with controls from the same population all found a significantly increased risk of atopic disorders in CU. Results should however be interpreted with caution as high heterogeneity was found in all analyses.