Migration within Great Britain and cardiovascular disease: early life and adult environmental factors

Aim To examine the relative contributions of early life and adult life factors to risk of cardiovascular disease (CVD) in middle-aged men using migration within Great Britain (GB). Methods Prospective study of 7735 men (40-59 years) drawn from one group practice in each of 24 British towns. Zones of birth and/or examination: South of England and rest of GB (Midlands and Wales, North of England, and Scotland). Results There were 1392 coronary heart disease (CHD) events and 1154 cardiovascular deaths during 21.8 years mean follow-up. Regardless of birth zone, men examined in the South showed lower risk of CHD events and CVD mortality than those examined in the rest of GB. Migrants from South to rest of GB showed a small increase in cardiovascular risk. Men born and examined in the rest of GB showed the highest adjusted risk of CHD events (RR = 1.15, 95% CI: 0.96-1.38) and CVD mortality (RR = 1.28, 95% CI: 1.04-1.57). Men born in the rest of GB who moved to the South showed adjusted risks of CHD events and CVD mortality similar to those born and examined in the South. Zone of examination was more strongly associated with CHD events and CVD mortality than zone of birth (RR = 1.23 versus 0.95 for CHD; RR = 1.26 versus 1.04 for CVD mortality). Smokers, irrespective of zone of birth or examination, showed higher risk than non-smokers. Conclusion Factors in adult life appear to be dominant in determining cardiovascular risk in middle and older age although this does not exclude early life effects on cardiovascular risk.