title: Prevalence of hypertension in 13-year-old adolescents in Porto, Portugal.
abstract: OBJECTIVE
  To describe the prevalence of hypertension and associated features in 13-year-old urban adolescents.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  We evaluated 2023 adolescents (1043 female and 980 male), born in 1990 and enrolled at public and private schools in Porto during the 2003/2004 school year.
  
  
  METHODS
  Data on behavioral, social and demographic characteristics and individual and family history of disease were collected using two standardized questionnaires (one completed at home and the other by the adolescents at school). After completion and return of the home questionnaires, our research team visited the schools and detailed physical examinations were carried out, including measurement of blood pressure, height and weight. Blood pressure was measured on a single occasion, and classified according to the American Academy of Pediatrics' recommendations: as hypertension if systolic (SBP) and/or diastolic blood pressure (DBP) were above the 95th percentile for gender, age and height; and as prehypertension if SBP and/or DBP levels were above the 90th percentile but both < the 95th percentile. Data were analyzed separately for males and females. Proportions were compared using the chi-square test, and quantitative variables were compared using the Kruskal-Wallis test.
  
  
  RESULTS
  The prevalence of hypertension was 22.0% and of prehypertension 13.3%. The prevalence of hypertension was higher in males (25.4% vs. 18.8%). For both genders blood pressure increased with body mass index. In females, the prevalence of hypertension was 14.7% for normal weight, 24.2% for overweight and 42.3% for obese (p < 0.001). In males, the prevalence was 20.4%, 35.5% and 41.3% respectively (p < 0.001).
  
  
  CONCLUSIONS
  This sample of 13-year-old adolescents presented high blood pressure levels. We found 22.0% with hypertension and 13.3% with prehypertension, with males presenting higher values. We also found that body mass index was related to blood pressure.
authors.affiliation: Serviço de Higiene e Epidemiologia, Faculdade de Medicina da Universidade do Porto, Porto, Portugal.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Ramos
authors.forename: Henrique
authors.initials: H
authors.lastname: Barros
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D008297:Male; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence