Background: It has been suggested that early life exposures are important determinants of geographical variations in adult diseases. We examined inter-regional migrants in Britain to evaluate the relative importance of early and recent exposures for adult cardiorespiratory risk factors, mental ill-health and sensory function.
Methods: A total of 9023 persons born throughout England, Scotland and Wales during 1 week in 1958 were followed periodically through childhood into adulthood. At 44-45 years, height, body mass index (BMI), blood pressure (BP), glycosylated haemoglobin, total and high-density lipoprotein (HDL) cholesterol, triglycerides, fibrinogen, total immunoglobulin E (IgE), one-second forced expiratory volume (FEV1), hearing threshold at 4 kHz, visual impairment, symptoms of depression and anxiety, and chronic widespread pain were measured. Analysis of migration between 12 regions included 3125 cohort members who were examined in a region different to their birthplace.
Results: Height, BMI, diastolic BP (DBP), FEV1, log-transformed IgE and hearing threshold varied by region among non-migrants (each P < 0.05). Among inter-regional migrants, the spatial associations with current region, independent of birthplace, followed closely the geographical pattern shown among non-migrants for BMI, DBP and FEV1 (each P < 0.001). In contrast, of the 15 outcomes, only adult height was related to region of birth, after adjustment for region of examination (P = 0.002)
Conclusions: Although individual disease risk is predicted by early life factors, early exposures do not explain regional variations in cardiovascular and respiratory risk factors among middle-aged adults in Britain. Geographical inequalities in cardiorespiratory health are more strongly related to factors associated with region of examination that influence obesity, BP and ventilatory function.