Obesity and migration factors are associated with asthma in ethnic populations

Introduction: Migrants have higher asthma prevalence than respective host populations. Obesity has been implicated, but comparative data between ethnicities are incomplete. We sought to determine the association between obesity, migration and asthma, and if these were modified by ethnicity. Methods: We investigated UK biobank study participants who self-identified as White, South-Asian, Black or Chinese. Asthma was defined as current (past 12 months) asthma symptoms, medication use or doctor diagnosis. Cross-sectional associations were determined using logistic regression, and effect modification using interaction analysis. Results: We analysed 472,612 White (W), 9,879 South-Asian (SA), 8,058 Black (B) and 1,573 Chinese (C) adults. Being born in the UK, compared to abroad, was differentially associated with asthma between ethnic populations (OR=1.19 (W), 1.18 (SA), 1.38 (B), 2.47 (C), p-int<0.05) as was each decade of UK residence (OR=1.04 (W), 1.09 (SA), 1.13 (B) 1.18 (C), p-int<0.05). Obesity was differentially associated with asthma between ethnicities (OR=1.84 (W), 1.72 (SA), 1.78 (B), 2.61 (C), respectively, p-int <0.05). A risk table based on clinico-demographic profile is shown below. Conclusion: Obesity and UK residence are associated with asthma and these are modified by ethnicity. Clinico-demographic profiles could help identify high-risk populations for intervention.