Plasma homocysteine levels in indigenous Australians

Objectives: To determine plasma homocysteine levels in indigenous Australians living in urban areas, and the relationship of these levels with other risk factors in this population. Design: Cross-sectional study. Subjects and setting: 365 urban indigenous Australian subjects, 153 men and 212 women, mean (SE) age 42 (1) years, ascertained without regard to history of atherosclerotic disease, in collaboration with community-based health centres in five indigenous communities in south-east Queensland, 1997-1998. Main outcome measures: Plasma homocysteine levels, age, sex, smoking history, metformin therapy, history of atherosclerotic vascular disease, serum creatinine level, red cell folate and serum vitamin B-12 levels. Results: 89 subjects (24%) had plasma homocysteine levels 15 mu mol/L or above. Homocysteine levels were higher in men than in women (men: 14.4 mu mol/L; 95% confidence interval [CI], 13.6-15.2; women: 11.9 mu mol/L; 95% CI, 11.4-12.5) (P<0.001); correlated with age (P<0.001); higher in current smokers (P=0.02); higher in subjects taking metformin therapy (P=0.007); and higher in subjects with a history of atherosclerotic vascular disease (P<0.001). Homocysteine levels were also correlated with serum levels of creatinine (P<0.001), red cell folate (P<0.001), and vitamin B-12 (P<0.001). Conclusions: These data indicate that the high plasma levels of homocysteine of Australian indigenous subjects are associated with a history of vascular disease, and correlated with, among other things, smoking, and folate and vitamin B-12 nutritional deficiency. These are potentially reversible risk factors, and our data suggest that focusing public health initiatives on these issues may reduce the high prevalence of cardiovascular disease in the Australian indigenous population.