We compared the mortality rate ratios, before and after adjustment for different risk factors, of black vs white adults in the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study. For persons 35 to 54 years old, the rate ratio of mortality for blacks vs whites decreased from 2.3 (unadjusted) to 1.9 when adjusted simultaneously for six well-established risk factors (smoking, systolic blood pressure, cholesterol level, body-mass index, alcohol intake, and diabetes) and decreased from 1.9 to 1.4 when adjusted for the six risk factors plus family income. Thus, approximately 31% of the excess mortality can be accounted for by six well-established risk factors and a further 38% by family income. This leaves 31% unexplained. Broader social and health system changes and research targeted at the causes of the mortality gap, coupled with increased efforts aimed at modifiable risk factors, may all be needed for egalitarian goals in health to be realized.
Mac W. Otten (1990) studied this question.