Cross-sectional differences in health status in US racial/ethnic minority groups: potential influence of temporal changes, disease, and life-style transitions.

Racial or ethnic comparisons reveal marked health differentials within the US population. However, attempts to interpret these differentials are fraught with both conceptual and methodological pitfalls and are politically charged. The interpretational issues vary according to whether minority groups have disproportionately higher or lower risk compared to whites and according to whether differences can be readily explained by adjusting for recognized risk factors. Particularly when existing models are not sufficient to explain racial or ethnic differences, or lack of differences where they might have been expected on the basis of risk factor profiles, attention to changes in risk factors and disease patterns over time may be an important aspect of the analysis. "Life-style" diseases emerge and increase over time with social change. Thus, a population in an early or middle stage of urbanization or modernization can be expected to have a different epidemiologic profile from another population for which these processes are well established. Judging from the available time-trend data, US minority groups are at varying stages of chronic disease emergence. Attention to temporal changes will be critical if the increased emphasis on analyses involving race or ethnicity is to serve, rather than inhibit, the public policy and scientific objectives of these comparisons.