Blood pressure and migration: a study of Bengali immigrants in East London.

Abstract

SUMMARY The role of blood pressure in explaining the increased risk of ischaemic heart disease (IHD) in Bengali immigrants living in the East End of London was studied in a comparative population study. In addition the effect on blood pressure of age, body mass, and duration of stay in the UK was evaluated. The Bengalis had significantly lower mean systolic and diastolic blood pressures though these differences disappeared after adjustment for age and body mass. Both groups, however, showed similar rises of blood pressure with increasing age and body mass. The effect on blood pressure of duration of time spent in the UK by the Bengalis could not be separated from that due to age, given the association between them. It seems unlikely that increasing duration of stay in inner London per se has a hypertensive effect on Bengali immigrants coming from a rural community. Further, the increased IHD risk in this group is not explained, even in part, by an increase in blood pressure.Immigrants from Bangladesh living in the East End of London are reported as having a greater than expected incidence of myocardial infarction.' It is likely that high dietary fat and, in men, cigarette smoking explain part of the increased risk as compared to the indigenous population.2 A third possibility is that elevated blood pressure might be relevant. Thus the environmental change associated with migration from the rural region of Sylhet in Bangladesh to the urbanised and relatively multi-deprived area of inner London might result in a rise in blood pressure, and the latter could be related to duration of stay in the United Kingdom. The objectives of this study were, therefore:1 to compare the blood pressure in Bengali immigrants with that ofthe indigenous population; 2 to compare the effects of age and other possible predictors on blood pressure in the two populations; and 3 to determine the effect of duration of stay in the UK on blood pressure in the Bengalis. Methods SUBJECTSSubjects were drawn from the age-sex register of a local multi-ethnic general practice. All patients aged 35-64 were identified, and attempts were made during the course of a 12 month period to invite them to attend a special screening clinic in the surgery, or to have them screened at the health centre on attendance for another reason. The original population from the age-sex register was 2082, including 1086 Caucasians of UK origin and 655 Bengalis, but the high population mobility in this area resulted in considerable inaccuracy in the age-sex register. Using similar methods to those ofa previous study,3 the best estimate was that 989 European and 312 Bengali patients were available for screening, of whom 617 (63%) Europeans and 155 (50%) Bengalis were screened during the 12 month period. METHODSAll assessments were made by a single observer (EL). The Bengali patients were asked to bring, if necessary, an English speaker with them, though an interpreter was available. Information on age for the Bengalis was verified where possible using official documents thou...