Inter-relationships between haemostatic tests and the effects of some dietary determinants in the Caerphilly cohort of older men.

Inter-relationships between fibrinogen, platelets and other haemostatic factors were examined in 1030 men aged 55-99 years. Fasting blood was taken and used for cell counts, platelet counts and platelet parameters, aggregation of platelets to ADP by a whole blood method and a filter test of platelet activation. Plasma fibrinogen, von Willebrand factor, factor VII and plasma viscosity were measured by standard methods. A stressed bleeding time was conducted on the forearm of the arm not used for venepuncture. Variability within the laboratory and short-term intra-subject variation were examined and found to be acceptably small. The effect of age on the tests was modest, except for von Willebrand factor which increased by about 50% of a SD for every 10 years of age. Cholesterol and triglyceride levels had small effects on the platelet tests and a large effect on factor VII. A number of dietary and life-style determinants were examined: smokers had increased levels of fibrinogen, viscosity and white cell count and reduced bleeding times. Alcohol drinkers showed reduced platelet activity and have lower levels of fibrinogen, von Willebrand factor and white cell count. Men who took fish oil capsules had substantially increased bleeding times and lower levels of von Willebrand factor and men who took capsules containing an extract of garlic showed reduced platelet retention in the filter test.