Plain language summary
The term “urticaria” is widely used to define a skin manifestation characterised by the onset of itchy, fleeting wheals of variable size, shape, and distribution. Using a temporal criterion, urticaria can be classified into acute and chronic: in chronic urticaria (CU), manifestations occur daily or nearly daily and last for more than 6 weeks. The aim of this study was to assess the overall risk of thyroid autoimmunity in people with diagnosis of CU. This study is a systematic review and meta-analysis of nineteen case-control studies. The studies provided information on 14,351 patients with CU (cases) and 12,404 subjects without CU (controls). Results show that the diagnosis of CU was associated with an approximately fivefold higher risk of exhibiting positivity for anti-thyroperoxidase antibodies [a marker of chronic autoimmune thyroiditis]. Authors conclude that their findings point to the opportunity to perform a screening for thyroid autoimmunity in the presence of CU.
Abstract
PURPOSE Autoimmunity has been implicated in some patients with idiopathic chronic urticaria (CU). Because of the frequency of autoimmune thyroid diseases, their association with CU deserves special attention. We tested both the existence and the extent of an association between thyroid autoimmunity and CU. METHODS A thorough search of PubMed, Scopus, Web of Science, and Cochrane databases was performed. Studies reporting the positivity rate for anti-thyroperoxidase antibodies (TPOAbs) in people with (cases) and without CU (controls) were included. Quality of the studies was assessed by the Newcastle-Ottawa Scale. Between-study heterogeneity was assessed by Cochrane Q and I2 tests, and the odds ratio (OR) for TPOAbs positivity was combined using random-effects models. RESULTS Nineteen studies provided information about TPOAbs positivity on 14,351 patients with CU and 12,404 controls. The pooled estimate indicated a more than fivefold increased risk of exhibiting TPOAbs positivity in the group with CU (pooled OR 5.18, 95% CI 3.27, 8.22; P < 0.00001). Correction for publication bias had a negligible effect on the overall estimate (pooled adjusted OR: 4.42, 95% CI 2.84, 6.87, P < 0.0001). Between‑study heterogeneity was established (I2 = 62%, Pfor heterogeneity = 0.0002) and when, according to meta‑regression models, a sensitivity analysis was restricted to the 16 studies with the highest quality scores, the OR for TPOAbs positivity rose to 6.72 (95% CI 4.56, 9.89; P < 0.00001) with no significant heterogeneity (I2 = 31%, Pfor heterogeneity = 0.11). CONCLUSIONS Patients with CU have a five-to-nearly sevenfold higher risk of displaying TPOAbs positivity. All patients with CU may well be offered a screening for thyroid autoimmunity.
Methodological quality
Jadad score
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Not applicable
Allocation concealment
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Not applicable
