Birthplace predicts risk for prehospital sudden cardiac death in middle-aged men who migrated to metropolitan area: The Helsinki Sudden Death Study.

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 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.