Mapping geographical variation in obesity in Finland.

BACKGROUND

The prevalence of obesity varies across countries. However, less is known about the geographical, within-country variation. This study investigated and visualized the geographical differences in general obesity defined by body mass index (BMI) and in abdominal obesity defined by waist circumference and waist-to-hip ratio (WHR) in Finland.

SUBJECTS AND METHODS

Data for the study consisted of three large population surveys: Health 2000 Survey with a nationally representative sample together with the National FINRISK Study conducted in five areas in 1997 and six areas in 2002. Altogether, 17 816 men and women aged 30-64 years participated in the surveys. In each survey, subjects' weight, height and circumferences of waist and hip were measured. The geographical pattern of mean anthropometric values and obesity prevalence were studied applying a Bayesian hierarchical approach and Geographical Information Systems.

RESULTS

Both in men and women, the prevalence of obesity (BMI >/= 30 kg m(-2)) varied little across geographical areas, but it was smaller in cities compared with other areas across the country. In men, the prevalence of abdominal obesity defined both by waist circumference and WHR was higher in western Finland compared with southern and northern Finland. Also in women, the prevalence of abdominal obesity was highest in western Finland, especially as defined by waist circumference.

CONCLUSIONS

Geographical variation in BMI was different and less prominent than in waist circumference and WHR. Abdominal obesity was surprisingly high in western Finland, the area seldom investigated. Mapping obesity gives a useful tool for professionals working in the field of health promotion.