Autoimmune thyroid disease as a risk factor for angioedema in patients with chronic idiopathic urticaria: a case-control study

CONTEXT AND OBJECTIVE: An association between chronic idiopathic urticaria (CIU) and autoimmune thyroid disease (ATD) has been reported. However, there have not been any reports on whether ATD raises the risk of angioedema, which is a more severe clinical presentation of CIU. Thus, the aim of the present study was to evaluate whether the risk of angioedema is increased in patients with CIU and ATD. DESIGN AND SETTING: Case-control study including 115 patients with CIU at a tertiary public institution. METHODS: The patients were evaluated with regard to occurrence of angioedema and presence of ATD, hypothyroidism or hyperthyroidism. RESULTS: Angioedema was detected in 70 patients (60.9%). There were 22 cases (19.1%) of ATD, 19 (16.5%) of hypothyroidism and nine (7.8%) of hyperthyroidism. The risk among patients with ATD was 16.2 times greater than among those without this thyroid abnormality (confidence interval, CI = 2.07-126.86). The odds ratio for hypothyroidism was 4.6 (CI = 1.00-21.54) and, for hyperthyroidism, 3.3 (CI = 0.38-28.36). CONCLUSIONS: Patients with CIU and ATD presented greater risk of angioedema, which reinforces the idea that a relationship exists between this allergic condition and thyroid autoimmunity. This finding could imply that such patients require specifically directed therapy.