Twenty-five year trends in body mass index by education and income in Finland

Ritva Prättälä,Eva Roos,Mikko T Laaksonen,Marjaana Lahti-Koski,Tomi Mäkinen,Risto Sippola

doi:10.1186/1471-2458-12-936

Abstract

BackgroundThe socioeconomic gradient in obesity and overweight is amply documented. However, the contribution of different socioeconomic indicators on trends of body mass index (BMI) over time is less well known. The aim of this study was to investigate the associations of education and income with (BMI) from the late 1970s to the early 2000s.MethodsData were derived from nationwide cross-sectional health behaviour surveys carried out among Finns annually since 1978. This study comprises data from a 25-year period (1978–2002) that included 25 339 men and 25 330 women aged 25–64 years. BMI was based on self-reported weight and height. Education in years was obtained from the questionnaire and household income from the national tax register. In order to improve the comparability of the socioeconomic position measures, education and income were divided into gender-specific tertiles separately for each study year. Linear regression analysis was applied.ResultsAn increase in BMI was observed among men and women in all educational and income groups. In women, education and income were inversely associated with BMI. The magnitudes of the associations fluctuated but stayed statistically significant over time. Among the Finnish men, socioeconomic differences were more complicated. Educational differences were weaker than among the women and income differences varied according to educational level. At the turn of the century, the high income men in the lowest educational group had the highest BMI whereas the income pattern in the highest educational group was the opposite.ConclusionNo overall change in the socio-economic differences of BMI was observed in Finland between 1978 and 2002. However, the trends of BMI diverged in sub-groups of the studied population: the most prominent increase in BMI took place in high income men with low education and in low income men with high education. The results encourage further research on the pathways between income, education, living conditions and the increasing BMI.

Highlights

The socioeconomic gradient in obesity and overweight is amply documented
Socioeconomic differences in body mass index (BMI) and their trends Mean BMI was consistently higher among men than women, with the mean increasing among both genders between the first period (1978–1982) and the last (1998–2002) (Table 1)
Among women education had an independent effect on BMI during each study period: women having the lowest educational level had the highest BMI even after adjusting for income

Summary

Introduction

The contribution of different socioeconomic indicators on trends of body mass index (BMI) over time is less well known. The aim of this study was to investigate the associations of education and income with (BMI) from the late 1970s to the early 2000s. Education and income are among the most common socio-economic indicators used in studies on obesity and overweight. European trend studies suggest that groups in 1986–2006 [11] and 1960–2008 [12] or did not find consistent changes in educational or income gradients (1970–2008) [13]. The previous trend studies do not give a consistent picture of educational and income-related gradients of BMI. The associations of education and income with BMI seem to change over time and vary by populations and their subgroups

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