Background: We examined age differences in levels of biological risk factors in the U.S. population by poverty status. It is not clear how socioeconomic status differentials in biological risk change with age because of mortality.
Methods: We used two nationally representative samples (National Health and Nutrition Examination Survey [NHANES] III, 1988-1994, and NHANES, 1999-2004) with data for more than 12,000 people aged 20 and older in each data set to examine biological risk for persons in families with incomes below and close to poverty level and those with higher income. We examined how mortality and life expectancy in the earlier sample are related to poverty status and biological risk. We examined life table survivorship to clarify how mortality differentially removes those who are poor and those with high biological risk from the population.
Results: Differences in biological risk by poverty status are larger before old age and become insignificant at older ages. Life expectancy at age 20 differs markedly by biological risk and poverty status.
Conclusions: Population differentials in health at older ages result from a lifetime of differences. Socioeconomic differences in health in old age disappear because of health and mortality differentials at earlier ages. Poorer people "age" earlier and this affects the age pattern of social differentials.