title: Socioeconomic inequalities in adolescent health 2002-2010: a time-series analysis of 34 countries participating in the Health Behaviour in School-aged Children study.
abstract: BACKGROUND
  Information about trends in adolescent health inequalities is scarce, especially at an international level. We examined secular trends in socioeconomic inequality in five domains of adolescent health and the association of socioeconomic inequality with national wealth and income inequality.
  
  
  METHODS
  We undertook a time-series analysis of data from the Health Behaviour in School-aged Children study, in which cross-sectional surveys were done in 34 North American and European countries in 2002, 2006, and 2010 (pooled n 492,788). We used individual data for socioeconomic status (Health Behaviour in School-aged Children Family Affluence Scale) and health (days of physical activity per week, body-mass index Z score [zBMI], frequency of psychological and physical symptoms on 0-5 scale, and life satisfaction scored 0-10 on the Cantril ladder) to examine trends in health and socioeconomic inequalities in health. We also investigated whether international differences in health and health inequalities were associated with per person income and income inequality.
  
  
  RESULTS
  From 2002 to 2010, average levels of physical activity (3·90 to 4·08 days per week; p<0·0001), body mass (zBMI -0·08 to 0·03; p<0·0001), and physical symptoms (3·06 to 3·20, p<0·0001), and life satisfaction (7·58 to 7·61; p=0·0034) slightly increased. Inequalities between socioeconomic groups increased in physical activity (-0·79 to -0·83 days per week difference between most and least affluent groups; p=0·0008), zBMI (0·15 to 0·18; p<0·0001), and psychological (0·58 to 0·67; p=0·0360) and physical (0·21 to 0·26; p=0·0018) symptoms. Only in life satisfaction did health inequality fall during this period (-0·98 to -0·95; p=0·0198). Internationally, the higher the per person income, the better and more equal health was in terms of physical activity (0·06 days per SD increase in income; p<0·0001), psychological symptoms (-0·09; p<0·0001), and life satisfaction (0·08; p<0·0001). However, higher income inequality uniquely related to fewer days of physical activity (-0·05 days; p=0·0295), higher zBMI (0·06; p<0·0001), more psychological (0·18; p<0·0001) and physical (0·16; p<0·0001) symptoms, and larger health inequalities between socioeconomic groups in psychological (0·13; p=0·0080) and physical (0·07; p=0·0022) symptoms, and life satisfaction (-0·10; p=0·0092).
  
  
  CONCLUSIONS
  Socioeconomic inequality has increased in many domains of adolescent health. These trends coincide with unequal distribution of income between rich and poor people. Widening gaps in adolescent health could predict future inequalities in adult health and need urgent policy action.
  
  
  BACKGROUND
  Canadian Institutes of Health Research.
authors: Institute for Health and Social Policy, and Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada. Electronic address: frank.elgar@mcgill.ca.
authors: Frank J
authors: FJ
authors: Elgar
authors: Institute of Medical Sociology, Health Services Research and Rehabilitation Science, University of Cologne, Cologne, Germany.
authors: Timo-Kolja
authors: TK
authors: Pförtner
authors: Institute of Medical Sociology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
authors: Irene
authors: I
authors: Moor
authors: Department of Public Health, Ghent University, Ghent, Belgium.
authors: Bart
authors: B
authors: De Clercq
authors: Utrecht Centre for Child and Adolescent Studies, Utrecht University, Utrecht, Netherlands.
authors: Gonneke W J M
authors: GW
authors: Stevens
authors: Child and Adolescent Health Research Unit, School of Medicine, University of St Andrews, St Andrews, UK.
authors: Candace
authors: C
authors: Currie
mesh_terms: D000293:Adolescent; D016497:Adolescent Health Services / Q000592:standards / Q000706:statistics & numerical data; D001835:Body Weight; D002908:Chronic Disease / Q000453:epidemiology; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D014943:Global Health / Q000706:statistics & numerical data; D054624:Health Status Disparities; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006801:Humans; D007182:Income; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D010549:Personal Satisfaction; D012959:Socioeconomic Factors