How does ethnicity affect asthma prevalence?

Melissa Whitrow and Seeromanie Harding from the Social and Public Health Sciences Unit of the Medical Research Council, UK, used data taken from 51 London schools to investigate a random selection of 11-13 year old pupils. The final sample for analysis included 1219 children who identified themselves as 'White UK', 933 'Black Caribbean', 1095 'Black African', 459 'Indian', 215 'Pakistani', 392 'Bangladeshi' and 299 'Mixed White UK and Black Caribbean'.

According to Whitrow and Harding, "Social and environmental factors may influence risk of asthma through early life exposures regulating the allergic inflammatory response and/or later life exposures to allergens. A positive association between body mass index (BMI) and asthma has also been reported. We aimed to investigate the influence of these factors on ethnic differences in asthma prevalence."

The researchers found that a family history of asthma and psychological well-being were consistent correlates for asthma regardless of ethnicity. Less than six years of residence in the UK had an independent protective effect for Black Caribbeans and Black Africans, possibly reflecting continuing protection from early life exposures in their home countries. A gender difference was observed for Indians and Bangladeshis, with less asthma in girls than boys. Speaking about these results, the authors said, "These findings point to early protective influences which are not properly understood. International comparisons could provide useful insights into prevention of asthma, for ethnic minority children and for all children."