Overweight, obesity and high blood pressure in an ethnically diverse sample of adolescents in Britain: the Medical Research Council DASH study

Objectives: To examine the impact of overweight on mean, high normal and high blood pressure in early adolescence, and how this relates to ethnicity and socio-economic status. Design: Cross-sectional study with anthropometric and blood pressure measurements. Setting: A total of 51 secondary schools in London. Sample: A total of 6407 subjects, 11–13 years of age, including 1204 White UK, 698 Other Whites, 911 Black Caribbeans, 1065 black Africans, 477 Indians and 611 Pakistanis/Bangladeshis. Main outcome measures: Mean, high normal (gender, age and height-percentile-specific 90–94th percentile) and high (greater than or equal to95th percentile) blood pressure. Results: Based on the International Obesity Task Force age-specific thresholds, 19% of boys and 23% of girls were overweight, and 8% of each were obese. Overweight and obesity were associated with large increases in the prevalence of high normal and high blood pressures compared with those not overweight. The increases in the prevalence of high systolic pressure associated with overweight were as follows: boys, odds ratio 2.50 (95% confidence intervals 1.73–3.60) and girls 3.39 (2.36–4.85). Corresponding figures for obesity were: boys 4.31 (2.82–6.61) and girls 5.68 (3.61–8.95). Compared with their White British peers, obesity was associated with larger effects on blood pressure measures only among Indians, despite more overweight and obesity among black Caribbean girls and overweight among Black African girls. The effect of socio-economic status was inconsistent. Conclusions: The tendency to high blood pressure among adult Black African origin populations was not evident at these ages. These results suggest that the rise in obesity in adolescence portends a rise in early onset of cardiovascular disease across ethnic groups, with Indians appearing to be more vulnerable