International Journal of Epidemiology 2002;31:1054–1060

There is a well-established geographical gradient in cardio-vascular mortality in Great Britain (GB) with the highest rates in Scotland and the lowest rates in the south.1 Studies of migration within GB have been used to investigate the relative contribution of circumstances in childhood and adult life to cardiovascular disease risk.2 The logic in these studies is that if the risk of cardiovascular disease (CVD) among people migrating from a low incidence to a high incidence area increases with time, or the risk among people migrating from a high incidence area to one of low incidence decreases with time, it is likely that factors acting in later life are of key importance. If the migrants retain the risk of their area of origin, it is likely that genetic or early life factors exert the major influence. However, previous studies of migrants within GB have pro-duced conflicting results.2–4 In an earlier report from the British Regional Heart Study (BRHS) the geographical area of adult residence appeared to be of greater importance in determining the risk of coronary heart disease (CHD) incidence than place of birth,2 whereas a national study of proportional mortality ratios in England and Wales suggested a significant influence from birthplace for deaths from CHD and stroke.3 In a later study of migrants within England and Wales, mortality rates from CHD were found to be related in almost equal measures to region of origin and to region of residence in later life.4 The conclusion from the earlier BRHS report was based on 8 years follow-up and relatively few cardiovascular events, and none of these three internal migration studies assessed the role of social class or individual adult lifestyle factors on the findings observed. The purpose of this paper is to examine the role of early life environment and adult life factors in determining the risk of cardiovascular disease, a subject of current debate.5 We ai