title: Clustering of biological risk factors for cardiovascular disease and the longitudinal relationship with lifestyle of an adolescent population: the Northern Ireland Young Hearts Project.
abstract: OBJECTIVE
  To determine whether clustering of biological cardiovascular disease (CVD) risk factors exists and to investigate the longitudinal relationship between lifestyle parameters (dietary intake, physical activity and smoking behaviour) and clustering of biological CVD risk factors, which was defined as belonging to one or more sex-specific 'high-risk' quartiles for the ratio between levels of total serum cholesterol and high-density lipoprotein cholesterol, diastolic blood pressure, body fatness (sum of four skinfolds) and cardiopulmonary fitness (number of laps accomplished on a 20 m shuttle-run test).
  
  
  METHODS
  The study was part of the Northern Ireland Young Hearts Project, a 3-year observational longitudinal study concerning adolescent boys (n=229) and girls (n=230) who were initially aged 12 years. The longitudinal relationships 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. Smoking was the only lifestyle parameter related to this clustering and was observed only among girls (rate ratio 1.5, P < 0.01); furthermore, none of the lifestyle parameters was significantly related to this clustering.
  
  
  CONCLUSIONS
  Because biological CVD risk factors tend to cluster, it is important 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.
authors.affiliation: Institute for Research in Extramural Medicine, Medical Faculty, Vrije Universiteit, Amsterdam, The Netherlands. jwr.twisk.emgo@med.vu.nl
authors.forename: J W
authors.initials: JW
authors.lastname: Twisk
authors.forename: C
authors.initials: C
authors.lastname: Boreham
authors.forename: G
authors.initials: G
authors.lastname: Cran
authors.forename: J M
authors.initials: JM
authors.lastname: Savage
authors.forename: J
authors.initials: J
authors.lastname: Strain
authors.forename: W
authors.initials: W
authors.lastname: van Mechelen
mesh_terms: D000293:Adolescent; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology*; D002648:Child; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D010807:Physical Endurance; D011237:Predictive Value of Tests; D015995:Prevalence; D012044:Regression Analysis; D012307:Risk Factors; D012885:Skinfold Thickness
chemical_list: D008076:Cholesterol, HDL; D002784:Cholesterol