Coagulation and clot-lysis studies in groups eating high and low fat diets: I. Comparison of East Africans with New Yorkers

Abstract

The occurrence rate of coronary thrombosis and myocardial infarction as well as venous thrombosis and pulmonary thromboembolic phenomena are extremely low in indigenous East Africans as compared with corresponding occurrence rates among Caucasians in the United States. Differences in occurrence rates could be due to differences in degrees of atherosclerosis (local factor) or to differences in the clotting properties of the blood (hematologic factor) or both. In the current study, in an attempt to obtain some insight into the mechanisms accounting for differences in the two population groups, we have investigated various factors related to coagulation and clot-lysis in plasma obtained from two groups of indigenous East African males, a medical student group with ages ranging from 20 to 30 years, and an outpatient group aged 30–60 years; and have compared these factors with corresponding factors in age-matched groups of New York males. Plasma fibrinogen and prothrombin levels of the two East African groups were significantly lower than those of the two age-matched corresponding New York groups. A definite increase in fibrinogen levels with age was noted in both East Africans and New Yorkers, and the binding power in the thrombelastograph was directly proportional to the fibrinogen levels. Euglobulin lysis times of the East African groups were significantly shorter than those of the age-matched corresponding New York groups. The thrombelastographic study was carried out only on the two medical student groups, and the clot-lysis times of the East African medical student group were significantly shorter that those of the New York medical student group. To what extent these significant differences in fibrinogen and prothrombin levels and clot-lysis times in the East African and New York groups account for the significant differences in the incidence of thromboembolic phenomena is difficult to determine. Higher values for various coagulation factors and prolonged lysis times do not necessarily mean a hypercoagulable state, and many more aspects of thrombogenesis must be assessed before causal mechanisms can be elucidated.