The Food and Drugs Administration's (FDA's) approval of the heart drug BiDil® marks a new understanding of health disparities. These differing patterns of death and disease are seen in subpopulations defined by age, gender, race, ethnicity, geographic location, environment, education or income.
As a drug specifically for African Americans, its approval signals that the FDA at least recognizes that genetic differences make subpopulations more or less likely to succumb to specific diseases or to benefit from particular treatments.
The U.S. government has made the reduction of health disparities a priority. Yet, in the US the intransigence of these observed differences, given the amount of effort and resources expended to reduce them, would seem to be reason enough to question exactly what is really known about health disparities and the role of biology. BiDil represents a broader acceptance of a genetic approach to understanding health disparities.
The most recognized genetic-based health disparity is that women live longer than men. Certain ethnic, racial and related geographic biological differences are well known. Jews from specific geographic regions carry genes associated with Tay-Sachs disease and certain breast cancers. African Americans have a greater tendency to have the sickle cell trait. African American women have a lower risk of developing breast cancer than White women, yet are more likely to die from the disease.
The recognition of biological causes of health disparities associated with race and ethnicity raises fears that these differences will be used to discriminate against minorities rather than benefit them. Moreover, some consider the characterization of health disparities by race and ethnicity to be arbitrary, pejorative and scientifically indefensible because of the vast differences among persons that may be grouped by racial and ethnicity categories. Yet, ignoring biology can only limit the understanding of why certain people get sick and how best to treat them.
Genetics not only predispose specific subpopulations to particular diseases, but also affect the efficacy of treatments for subpopulations. The FDA noted in its 2003 Guidance for Industry Collection of Race and Ethnicity Data in Clinical Trials that racially and ethnically distinct subgroups of the U.S. population differ in response to medical products because of genetic factors. For example, Whites are more likely than persons of Asian and African heritage to have abnormally low levels of an important enzyme that metabolizes certain drugs, such as antidepressants, antipsychotics, and beta blockers. In 2001 FDA, approved a new glaucoma drug, Travatan®, which has greater effectiveness in African Americans.
The National Institutes of Health (NIH) funds the emerging field of pharmogenomics, the study of how genes affect the way subpopulations respond to medicines, including antidepressants, chemotherapy, drugs for asthma and heart disease, and many others. The ultimate goal of this research is to help tailor medicines to a patient's unique genetic make-up for greater efficacy and safety. The NIH's environmental health research also examines possible genetic contributions to certain health risks, such as cancer, in specific subpopulations.
Genetics may explain why the frequency of specific diseases in the U.S. varies by geographic region as well as race and gender. Genetics also may unravel some of the causes of disparities in health status from country to country. Why, for example, do Japanese women on average live almost 85 years, five more than American woman, and Japanese men on average 78 years, four more than American men? (Asian Americans also have death rates lower than White Americans.) Why do Korean men have a relatively very low rate of prostate cancer? And why do U.S. infant mortality rates exceed most Organization for Economic Cooperation and Development countries at 6.8 per 1,000 live births, far higher than Iceland, Japan, Finland, Norway, Sweden or Spain, whose rates are under 4.0?
Of course, health disparities result from multiple factors including differences in healthcare, environment, income, education and the like. Yet, the role of genetics can no longer be ignored. Maybe research on the reason women live longer than men will help achieve a better understanding of the aging process, help us live as long as our wives, and balance the gender ratio in retirement communities and nursing homes.
John J. Cohrssen is an attorney and executive director of the Public Health Policy Advisory Board; J. Donald Millar, M.D., is a distinguished fellow with the Public Health Policy Advisory Board, a consultant on occupational health, and former director of the National Institute of Occupational Safety Health.