Elsevier

The Lancet

Volume 385, Issue 9982, 23–29 May 2015, Pages 2088-2095
The Lancet

Articles
Socioeconomic inequalities in adolescent health 2002–2010: a time-series analysis of 34 countries participating in the Health Behaviour in School-aged Children study

https://doi.org/10.1016/S0140-6736(14)61460-4Get rights and content

Summary

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.

Findings

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).

Interpretation

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.

Funding

Canadian Institutes of Health Research.

Introduction

Adolescence is a formative life stage for adult health, but is often neglected in health policy.1 Health and health behaviours track strongly from early adolescence to adulthood, and inequalities in health are typically established early in life.2 Socioeconomic status (SES) is a major determinant of these inequalities.2 To grow up in impoverished and marginalised socioeconomic conditions shortens the lifespan and contributes to poor mental and physical health.3, 4 Some research has suggested that socioeconomic differences in health emerge in early childhood and then diminish in early adolescence, only to re-emerge in adulthood.5 However, most of the evidence in this area shows social class gradients in health at every stage of the life course, including adolescence.4, 6, 7

An understanding of trends in health inequalities and their social determinants is crucial so that policy can be developed to redress them.2, 8 The available evidence in this area relies heavily on local and national samples of young children.6, 7, 9 International studies of social inequalities in adolescent health are scarce and, as a result, predictions about future inequalities in adult health are not based on robust information. Findings from the Health Behaviour in School-aged Children (HBSC) study,4, 8, 10 which surveys the health of adolescents in North America and Europe, have shown SES differences in health in most countries and health domains, including self-rated health, psychological and physical symptoms, and life satisfaction. However, this research has not focused on trends in health inequalities in adolescence, nor on structural determinants of adolescent health, such as national wealth or income inequality.1, 11, 12

Income inequality is rising13 and health inequalities are widening14, 15 in adults, suggesting that socioeconomic differences in adolescent health might have increased in recent years. Since the 1970s, real wages for the bottom half of the workforce have fallen in many countries, while incomes of the top 1% have quadrupled.12 Income inequality has risen steadily during the past four decades, thus increasing relative deprivation, depleting the social capacity of nations to support health, and contributing to poor health in terms of mental illness, obesity, mortality, and reduced child wellbeing.16 Thus, rising income inequality might have both worsened adolescent health in general and widened social inequality in adolescent health over time.12 In a Series on adolescent health, Viner and colleagues1 concluded that the strongest determinants of adolescent health worldwide are structural factors, such as national wealth, access to education, and income inequality.

We had two goals for this study. Our first objective was to examine secular trends in health inequalities in different domains of adolescent health: physical activity, bodyweight, psychological and physical symptoms, and life satisfaction. We chose these domains to broadly represent mental and physical health and wellbeing. Because adolescent health relates to SES, and SES differences might have widened because of increasing income inequality, we hypothesised that adolescent health inequalities in all health domains grew from 2002 to 2010. Our second objective was to explore whether national wealth and income inequality relate to international differences in adolescent health and health inequalities between SES groups.

Section snippets

Study design and participants

Data for SES and health used in this time-series analysis were collected in a series of cross-sectional surveys of adolescents in 34 North American and European countries or regions in the 2002, 2006, and 2010 cycles of the HBSC study: Austria, Belgium (French region), Belgium (Flanders region), Canada, Croatia, Czech Republic, Denmark, England, Estonia, Finland, France, Germany, Greece, Greenland, Hungary, Ireland, Israel, Italy, Latvia, Lithuania, Macedonia, Netherlands, Norway, Poland,

Results

Survey data were available for a pooled sample of 492 788 adolescents. School response rates varied by country (47–90%, but more than 70% for 21 of 34 countries). Student participant response rates varied by country, but were higher than 70% for almost all national surveys. In our sample, per person income ranged from US$730 (Ukraine, 2002) to $37 530 (Norway, 2010), and rose from an average of $17 165 in 2002 to $32 593 in 2010 (table 1). Income inequality ranged from 0·225 (Denmark, 2002) to

Discussion

From 2002 to 2010, average body-mass indices and physical symptoms slightly increased and became more unequal between socioeconomic groups. We also noted progressively larger SES differences over successive surveys of physical activity and psychological symptoms. These trends run in parallel to those previously reported in health inequalities in adult and child mortality,14, 29, 30, 31 and this study extends this evidence base to many health domains in an international sample of adolescents (

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