Ethnic variations in the haemostatic system: comparison between Arabs, Westerners (Europeans and Americans), Asians and Africans.

A wide variety of haemostatic variables were measured in healthy male subjects predominantly blood donors residing in Riyadh, the capital city of Saudi Arabia. Subjects were divided according to ethnic origin: Saudi Arabs n = 487, Westerners (Europeans and Americans) n = 300, South East Asians (Koreans and Filipinos) n = 360, and West Africans n = 82. There were no significant differences in prothrombin time, partial thromboplastin time, thrombin time, reptilase time, plasma fibrinogen, antithrombin, plasminogen and platelet count between Saudis, Westerners and Asians. Africans exhibited significantly lower plasma levels of fibrinogen, platelet count and plasminogen than other ethnic groups. Arabs and Africans had higher levels of FVIII:C and vWF:ristocetin cofactor than Westerners. On the other hand, FX was significantly higher in Westerners than in other ethnic groups. Smokers had higher fibrinogen levels than non-smokers. These variations, which could not be related to blood group distribution, physical parameters of height and weight, may be due to genetic and/or dietary habits. In conclusion, this study established the existence of racially determined variations in haemostatic variables, with Black Africans showing changes consistent with a lesser tendency towards atherosclerosis and cardiovascular disease than other ethnic groups. These variations should be taken into account when investigating the haemostatic system in patients.