Background: Eastern-born male Finns, irrespective of their place of residence, have high mortality from coronary heart disease (CHD), and half of such deaths are sudden.
Aim: To study whether eastern birthplace alone or combined with life-style factors predicts risk for prehospital sudden cardiac death (SCD) in the new (west) low-mortality area of residence.
Method: Prospective case-control autopsy study of all (700) out-of-hospital deaths of men aged 35-69 years in metropolitan Helsinki during 1981-82 and 1991-92. Data on CHD risk factors were obtained for 405, of whom 149 died of SCD (cases) and 256 of other causes (controls).
Results: A birthplace-by-age interaction with SCD (P=0.024) and with myocardial infarction (P=0.005) appeared. Men < or =54 years born in the east were more often victims of SCD (odds ratio 2.99, 95% confidence interval 1.38-6.49, P=0.006) than were men born in the west, independently of CHD risk factors. SCD was predicted also by alcohol consumption, age, smoking, and hypertension. Amongst older (>54 years) men no association with birthplace was any longer evident, but alcohol and socio-economic status predicted SCD.
Conclusions: Birthplace-based risk for SCD suggests the contribution of early life environment or genetic east-west differences, reflecting Finns' two-phase settlement history.