Geographical variations in plasma viscosity and relation to coronary event rates.

Plasma viscosity is reported to be predictive of coronary heart disease (CHD) and stroke. To find out whether regional differences in CHD event rates correlate with differences in plasma viscosity, we compared plasma viscosity in a high-risk area for CHD (Glasgow Multinational Monitoring of Trends and Determinants in Cardiovascular Disease [MONICA] and Scottish Heart Health Study population surveys, 1985/86; n = 1166) and in a lower-risk area (MONICA Augsburg survey, 1984/85; n = 3258) in men and women aged 25-64 years. Mean plasma viscosity (37 degrees C) was 1.261 (SD 0.067) mPa s in Augsburg and 1.327 (0.093) mPa s in the west of Scotland for men, and 1.248 (0.066) mPa s and 1.318 (0.087) mPa s, respectively, for women. The unadjusted difference of the means between the west of Scotland and Augsburg was 0.066 (95% CI from weighted regression 0.058-0.073) mPa s for men and 0.070 (0.062-0.078) mPa s for women. Adjustment for age, smoking behaviour, total and high-density-lipoprotein cholesterol, systolic and diastolic blood pressure, and body-mass index had no effect on these differences. Age-standardised coronary event rates in 1985-87 were at least two times higher among men, and four times higher among women, in MONICA Glasgow than in MONICA Augsburg. This large geographical difference in plasma viscosity might partly explain the differences in CHD event rates between these populations. Further studies are needed on the determinants of plasma viscosity, and on its potential roles in atherosclerosis, thrombosis, and ischaemia.