Antecedents of Cardiovascular Disease in Six Solomon Islands Societies

Abstract

Cardiovascular risk factors have been analyzed as part of a combined ethnographic, anthropometric, and medical study of 1390 adult subjects in defined populations representing six Solomon Islands Societies. The six societies, all at low levels of acculturation, differed in habitat, way of life, and exposure to Western civilization. Criteria for ranking the societies in respect to acculturation were developed based on demographic changes within defined populations, secular increase in adult height, length and intensity of contact with Western cultural influences, religious belief, education, availability of medical care, economy, and diet. The six tribal groups were ranked by these criteria as follows: (1) Nasioi, (2) Nagovisi, (3) Lau, (4) Baegu, (5) Aita, (6) Kwaio. Physical health and nutrition were good in all six groups, and clinical evidence of coronary heart disease and atherosclerosis was absent. Serum cholesterol levels were higher at almost all ages and both sexes in the three more acculturated than in the three less acculturated groups. Serum uric acid levels were lower in the more acculturated than in the less acculturated groups. Among adult males in all groups, systolic blood pressure showed no age-related trend while diastolic blood pressure declined with age in the three less acculturated groups. Among adult females systolic blood pressure increased significantly with age in the three more acculturated groups but showed no age trend in the less acculturated. Weight declined with age in all groups. Analysis of electrocardiograms by the Blackburn method showed striking absence of codable abnormalities in all groups and a lower frequency of most abnormalities associated with coronary disease than in any population previously reported. The differences in serum cholesterol and uric acid levels, and in intrapopulation trends of blood pressure in relation to age between the more and less acculturated groups were found to correlate best with dietary differences, especially in intake of salt, and of tinned meat and fish. The biologic differences noted may represent the earliest antecedents of cardiovascular disease in these societies.