People, places and coronary heart disease risk factors: a multilevel analysis of the Scottish Heart Health Study archive.

The Scottish Heart Health Study (SHHS), which recruited 5123 men and 5236 women between 1984 and 1986, was set up in part to investigate geographical variation in coronary heart disease in Scotland. Multilevel models are particularly appropriate for such hierarchical data, in which the individuals in the study can be represented by the lower level and the districts in which they live by the higher level. Multilevel models are presented for four coronary heart disease risk factors-diastolic blood pressure, cholesterol, alcohol consumption (defined both as units of alcohol consumed per week and as being a non-drinker) and smoking, for men and women separately. Significant district level variance was found for three out of the four variables studied, after controlling for socioeconomic and other variables considered at the level of the individual. These were for diastolic blood pressure, cholesterol and alcohol. Although the large majority of the variance was present at the individual level, the existence of significant variance at the district level is evidence that places may have a role in the distribution of coronary heart disease risk. Health policy aimed at reducing coronary heart disease should therefore consider the characteristics of places as well as individuals.