An inter-racial study into the pattern and prevalence of atherosclerotic peripheral vascular disease in the University-based vascular surgical service in Durban.
Maharaj, Rabindranath Ramsuk.
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This study investigates the clinical and major risk factor profiles in Whites, Indians and Blacks with atherosclerotic peripheral vascular disease at the Vascular Service in Durban; and compares them to that for coronary artery disease in the same race groups. The clinical profile for chronic peripheral vascular disease was established in a retrospective study of 2175 patients seen at the Vascular Service during 1981-1986. Atherosclerosis was confirmed in 1974 patients (92,3%) on the basis of clinical, doppler, angiographic and histological evidence. The disease predominantly affected the aorta and distal peripheral vessels. Extracranial cerebrovascular disease occurred less commonly in Blacks than in Whites and Indians. Occlusive disease was the most common pathological type in all race groups. Aneurysmal disease occurred mainly in the aorta with peripheral aneurysms being most common in Blacks. The disease manifested in Blacks at an . earlier age and more aggressively than in Whites and Indians. The risk factor profile for atherosclerotic peripheral vascular disease was established in a prospective study of 302 male patients consisting of 100 Whites, 97 Indians and 105 Blacks on the basis of historical, clinical and haematological data. The sample was randomly selected, and not strictly representative of the clinical pattern in the retrospective study. All patients were confirmed to have atherosclerosis on the basis of the previously mentioned criteria. Smoking was the single most common risk factor in all race groups. Hypertension occurred more commonly in Whites and Indians than in Blacks, while diabetes was commonest in Indians. Insulin resistance did not occur in Blacks, but was possibly present in Whites and Indians. Total cholesterol, LDL cholesterol and triglycerides were raised in Whites and Indians, but not in Blacks. HDL cholesterol was reduced in all 3 race groups. These findings suggest that contrary to the established view, atherosclerotic peripheral vascular disease is an established entity in Blacks seen at the Vascular Service in Durban without a concomitant increase in coronary and extracranial cerebrovascular disease. In Whites and Indians atherosclerosis occurred in all of the vascular beds. This could support the contention that in a socially developing society atherosclerosis affects the aorta and distal peripheral vessels before the coronary vascular bed. Since this occurs in the presence of normal levels of total cholesterol, LDL cholesterol and triglycerides, it does not support the contention that hypercholesterolaemic states are essential for atherosclerotic lesions to develop. On this basis it is postulated that with social transition there is a differential atherosclerotic involvement of the vascular beds due to a differential vascular susceptibility. Smoking is an important socio-environmental risk factor, while at the biochemical level a reduced HDL cholesterol and not a raised total cholesterol, LDL cholesterol or triglyceride could trigger the 'lipid pathway' in atherogenesis. It is further postulated that the differential vascular susceptibility does not exist in a fully developed society once lipid aberrations include a raised total cholesterol, LDL cholesterol and triglycerides. Insulin resistance/hyperinsulinaemia may play a role in the evolution of the disease within the coronary vascular bed.