High blood pressure in the Western Isles: a comparative study with Dundee

A screening programme for cardiovascular risk factors in men aged 50-59 was undertaken in North Uist, and the results compared with an age- and sex-matched control group from Dundee screened as part of the Scottish Heart Health Study. Blood pressure levels were higher in the Islanders than in controls (148 +/- 20/89 +/- 10 mmHg vs 134 +/- 19/84 +/- 11 mmHg (P less than 0.001). Analysis of standard twelve-lead electrocardiograms revealed a greater prevalence of left ventricular hypertrophy in the Islanders (51% vs 16%, P less than 0.005), suggesting that the recorded BP differences were real and not artefacts of measurement. The explanation for the higher BP on North Uist is less clear. Environmental factors that might influence BP including body mass index, the amount of exercise taken, alcohol consumption, dietary salt and potassium intake were similar in North Uist and Dundee. By contrast, an analysis of family names in the two centres indicated a greater degree of common ancestry in North Uist (28 surnames/84 islanders v 98 surnames/110 controls, P less than 0.001). These results suggest that known environmental causes of hypertension are not responsible for higher BP amongst men of North Uist, and this with the data on family names raises the possibility that genetic factors are more important.