Hemostatic factors in Australian Aboriginal and Torres Strait Islander populations

Abstract

Hemostatic processes are important in precipitating myocardial infarction and stroke. Elevated plasma fibrinogen is considered a risk factor for cardiovascular diseases (CVDs), but the results of previous studies on the association of plasma factor VIIc activity with CVD and diabetes have been inconsistent. The aim of the present study was to explore the association of plasma fibrinogen and factor VIIc to clinical characteristics and estimated coronary heart disease (CHD) risk in Aboriginal and Torres Strait Islander peoples. Cross-sectional surveys of Australian Aboriginal people (n = 852) and Torres Strait Islanders (n = 276) aged 15 years and older were conducted from 1993 to 1995. Anthropometric characteristics, blood pressure, fasting plasma fibrinogen, factor VIIc, total and high-density lipoprotein cholesterol, triglycerides, and glucose were measured. Levels of fibrinogen (mean, 95% confidence interval) for Aboriginal (3.52, 3.44-3.59 g/L) and Torres Strait Islander people (3.62, 3.49-3.75 g/L) were higher compared with previous reports from other populations. Factor VIIc (mean, 95% confidence interval) was especially high in Torres Strait Islanders (116%, 111%-122%) compared with Aboriginal people (99%, 97%-102%). Fibrinogen increased with age in both ethnic groups and sexes. Fibrinogen was independently associated with female sex, body mass index, renal dysfunction, low levels of high-density lipoprotein cholesterol and diabetes, whereas the independent predictors for factor VIIc were Torres Strait Islander ethnicity, female sex, body mass index, renal dysfunction, and total cholesterol. Average fibrinogen levels were high (>3.5 mg/dL) even for people considered “below average risk of coronary heart disease” according to conventional risk factor levels. For Aboriginal women, levels of fibrinogen and factor VIIc were significantly higher for persons at high risk than those at below average risk. The data suggest that plasma fibrinogen and factor VIIc might be important factors mediating the elevated CVD in Australian Indigenous Peoples. These data may have implications for prevention and treatment of CVD in Australian Indigenous communities.