Clustering of biological risk factors for cardiovascular disease and the longitudinal relationship with lifestyle of an adolescent population: The Northern Ireland Young Hearts Project

Objective To determine whether clustering of biological cardiovascular dise ase (CVD) risk factors exists and to investigate the longitudinal relations hip between lifestyle parameters (dietary intake, physical activity and smo king behaviour) and clustering of biological CVD risk factors, which was de fined as belonging to one or more sex-specific 'high-risk' quartiles for th e ratio between levels of total serum cholesterol and high-density lipoprot ein cholesterol, diastolic blood pressure, body fatness (sum of four skinfo lds) and cardiopulmonary fitness (number of laps accomplished on a 20 m shu ttle-run test). Methods The study was part of the Northern Ireland Young Hearts Project, a S-year observational longitudinal study concerning adolescent boys (n = 229 ) and girls (n = 230) who were initially aged 12 years. The longitudinal re lationships were analysed with generalized estimating equations. Results Significant clustering of biological CVD risk factors was observed both for boys and for girls, but the stability over time was rather low, Sm oking was the only lifestyle parameter related to this clustering and was o bserved only among girls (rate ratio 1.5, P < 0.01); furthermore none of th e lifestyle parameters was significantly related to this clustering. Conclusions Because biological CVD risk factors tend to cluster, it is impo rtant to investigate these risk factors together. However, for subjects in this age group, according to our analysis, lifestyle parameters were hardly related to this clustering. (C) 1999 Lippincott Williams & Wilkins.