Socio-economic position and coronary heart disease risk factors in youth - Findings from the Young Hearts Project in Northern Ireland

Background: This study investigates the existence of socioeconomic differentials in behavioural and biological risk factors for coronary heart disease in young people from Northern Ireland, taking into account differences in biological maturation. Methods: A school-based prospective study, with measurements in 1989/1990 and 1992/1993, Socio-economic position was based on occupational level of the main family breadwinner. Behavioural risk factors included were physical inactivity, the intake of total energy, dietary fat and a number of micronutrients. Biological risk factors included were blood pressure, body fatness, lipoproteins and cardio-pulmonary fitness. Biological maturation was based on Tanner's stages. Participants: 251 boys and 258 girls who were measured at the age of 12 years and re-examined at the age of 15 years. Results: Cross-sectional analyses showed that socio-economic differences in cholesterol intake tin boys) and physical inactivity and total energy intake tin girls) were present at 12 and 15 years of age, while differences in fat and fruit intake and smoking behaviour tin boys and girls) became established at the age of 15 years, with unfavourable levels in subjects in the manual group. Longitudinal analyses confirmed that differences in behavioural risk factors exist or develop during adolescence. No clear pattern of differences in biological risk factors was found by socio-economic position. Adjustment for biological maturation did not materially alter the results. Conclusion: Differences in lifestyle by socio-economic position seem to become established in adolescence. These differences however, are not (yet) reflected in differences in biological risk factors by socio-economic position.