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Open Access Highly Accessed Research article

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

Ritva Prättälä1*, Risto Sippola1, Marjaana Lahti-Koski2, Mikko T Laaksonen3, Tomi Mäkinen1 and Eva Roos34

Author Affiliations

1 National Institute for Health and Welfare, Helsinki, Finland

2 Finnish Heart Association, Helsinki, Finland

3 Hjelt Institute, Department of Public Health, University of Helsinki, Helsinki, Finland

4 Folkhälsan Research Center, Department of Public Health, University of Helsinki, Helsinki, Finland

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BMC Public Health 2012, 12:936  doi:10.1186/1471-2458-12-936

Published: 31 October 2012

Abstract

Background

The 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.

Methods

Data 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.

Results

An 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.

Conclusion

No 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.

Keywords:
Body mass index; 25-year time trends; Education; Income; Finnish men and women