Atopic Eczema-Associated Fracture Risk and Oral Corticosteroids: A Population-Based Cohort Study

BACKGROUND: Evidence suggests adults with atopic eczema have increased fracture risk. However, it is unclear whether oral corticosteroids explain the association. OBJECTIVE: To assess to what extent oral corticosteroids mediate the relationship between atopic eczema and fractures. METHODS: We conducted a cohort study using English primary care (Clinical Practice Research Datalink) and hospital admissions (Hospital Episode Statistics) records (1998-2016) including adults (18 years old and older) with atopic eczema matched (age, sex, and general practice) with up to 5 adults without atopic eczema. We used Cox regression to estimate hazard ratios (HRs) for specific major osteoporotic fractures (hip, spine, pelvis, or wrist) and for any-site fracture comparing individuals with atopic eczema with those without, adjusting for 6 different definitions of time-updated oral corticosteroid use (ever any prescription, ever high-dose, and recent, cumulative, current, or peak dose). RESULTS: We identified 526,808 individuals with atopic eczema and 2,569,030 without. We saw evidence of an association between atopic eczema and major osteoporotic fractures (eg, spine HR 1.15, 99% CI 1.08-1.22; hip HR 1.11, 99% CI 1.08-1.15) that remained after additionally adjusting for oral corticosteroids (eg, cumulative corticosteroid dose: spine HR 1.09, 99% CI 1.03-1.16; hip HR 1.09, 99% CI 1.06-1.12). Fracture rates were higher in people with severe atopic eczema than in people without even after adjusting for oral corticosteroids (eg, spine HR [99% CI]: confounder-adjusted 2.31 [1.91-2.81]; additionally adjusted for cumulative dose 1.71 [1.40-2.09]). CONCLUSIONS: Our findings suggest that little of the association between atopic eczema and major osteoporotic fractures is explained by oral corticosteroid use.