Trends in social inequalities in obesity: Belgium, 1997 to 2004
Section snippets
Background
In the last two decades, an alarming increase in the prevalence of overweight and obesity has been reported in North America and Europe (Flegal et al., 2002, WHO, 2007). This epidemic together with the considerable effects of obesity on mortality and morbidity, and the recent accrued interest in health inequalities has provoked a surge in the literature investigating the association between socioeconomic status (SES) and obesity. In the majority of these studies, a consistent inverse
Study population
We used data from three successive waves of the cross-sectional Health Interview Survey (HIS) carried out in Belgium in the years 1997, 2001 and 2004. The participants were selected from the national register through a multistage stratified sample of the non-institutionalized Belgian population aged 15 years and above. The participation rate was 58.5% in 1997, 61.4% in 2001, and 61.4% in 2004 (Bayingana et al., 2006). The detailed methodology of the survey is described elsewhere (Scientific
Obesity
Body weights and heights were reported by study participants in response to the following two questions: “How much do you weight (in kg) without shoes and clothes” and “What is your height (in cm) without shoes”. Based on this information, body mass index was calculated for each individual (BMI = weight [kg]/height [m2]). In accordance with WHO criteria, subjects with BMI ≥ 30 were considered obese (WHO, 1995).
Educational attainment
Socioeconomic position was determined based on the highest level of education achieved.
Data analyses
To assess changes overtime in educational inequalities in obesity, we illustrate graphically the age adjusted prevalence rates of obesity by educational level and year. In addition, as suggested in the literature (Krokstad et al., 2002, Mackenbach and Kunst, 1997), we present four complementary summary measures. First, we measure the prevalence difference between the lowest and highest educational groups. This measure expresses inequalities in absolute terms, making it possible to show the
Results
The characteristics of the study population in 1997, 2001 and 2004 are presented in Table 1. We observe a comparable distribution by educational level and body weight in the three cohorts. For age, there was an oversampling of the 65+ in the 2004 survey. The same patterns are observed for males and females.
Fig. 1 shows the age adjusted prevalence rates of male obesity by educational level in the three surveys. The two lowest educational categories witness an increase in the prevalence rates,
Discussion
This study suggests a widening in the social patterning of obesity for Belgian males and a persistent steep SES gradient for Belgian females. For males, a clear SES gradient was observed between obesity and education. This gradient witnessed a large increase between the years 1997 and 2004. These results echo the findings of Stam-Moraga et al. (1998) that suggested a more pronounced rise in obesity of working Belgian men in the lower educated groups compared to the higher educated ones. Social
Conclusion
Using three comparable nation-wide population-based surveys, our study has shown that in Belgium from 1997 to 2004, the SES gradient in obesity has increased for males and persisted for females. As well, our results indicate that compared to women, men had initially low SES gradient in obesity but the trend is towards catching up with the very steep SES gradient in female obesity. Future studies should look at the reasons behind such an evolution in the effect of SES on body weight.
Conflict of interest statement
The authors declare that there are no conflicts of interest.
Acknowledgments
This work was funded through a grant to the Scientific Institute of Public Health, Belgium from the Service Public Fédéral de Programmation Politique Scientifique (Contract # TA/00/15). Rana Charafeddine holds a postdoctoral fellowship from the Canadian Health Services Research Foundation.
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