Chronic urticaria and osteoporosis: a longitudinal, community-based cohort study of 11 944 patients.

BACKGROUND: Chronic urticaria (CU) carries many risk factors for osteoporosis, but data on the relationships between CU and osteoporosis are lacking. OBJECTIVES: To evaluate the association between CU and osteoporosis in a large community-based study. METHODS: A nationwide observational longitudinal cohort study was conducted. CU was defined as four pairs of urticaria diagnoses; each pair was recorded within a period of 6 weeks and was registered by physicians in a primary-care setting. Patients with CU and their age- and sex- matched controls were followed for the incidence of osteoporosis and other laboratory data between 2002 and 2017. Data regarding systemic steroid exposure and other relevant risk factors for osteoporosis were obtained. Analyses of risk for osteoporosis were performed in Cox regression models adjusted for age, sex, exposure to systemic corticosteroids, obesity, smoking and hyper- and hypothyroid disease. RESULTS: The study included 11 944 patients with CU and 59 829 controls. During the study's observation period, 1035 (8·7%) patients with CU were diagnosed with osteoporosis, compared with 4046 (6·8%) controls. The adjusted multivariate analysis demonstrated that CU was significantly associated with a higher risk for osteoporosis (hazard ratio 1·23, 95% confidence interval 1·10-1·37, P < 0·001). CONCLUSIONS: CU may impose a risk for osteoporosis. Appropriate targeted screening should be considered.