It's no revelation that men and women are different. But a growing body of medical research suggests that the sexes may be more dissimilar than previously thought.
For example, distinct biological differences have been noted in women's and men's organs and organ systems, including the heart, brain, bones, skin and saliva.
"By the next century, gender may be the most important factor affecting your health," said Dr. Mary Flack, director of endocrinology and diabetes for Parke-Davis, a pharmaceutical firm positioning itself as a leader in gender-specific research.
Gender-specific biology--the foundation for the emerging field of gender-based medicine--focuses on how gender and disease interrelate, how diseases affect men and women differently, and why certain diseases affect one sex but not the other.
Greater knowledge in these areas has potentially far-reaching implications for research, clinical practice, medical education and public health policy.
The term "gender-specific biology" was coined only about two years ago, and "it's amazing how this has taken off," said Dr. Florence Haseltine, founding president of the Society for the Advancement of Women's Health Research, a leading advocate of studying gender differences.
The change in focus contrasts sharply with the gender-blind approach of the past. For example, just a few years ago, two-thirds of clinical-trial participants were men, and it was assumed that the research findings would apply equally to women. In 1993, the National Institutes of Health required researchers receiving federal funds to include women in clinical trials unless there was a compelling reason to justify their exclusion.
The NIH is currently undertaking the most ambitious women's health study ever in the United States. The Women's Health Initiative is a $628-million, 15-year study that will include a randomized, controlled clinical trial examining strategies to prevent heart disease, osteoporosis, and breast and colorectal cancer in post-menopausal women.
The project has three components: an observational study, tracking the medical history and health habits of about 100,000 women over an eight- to 12-year span; the clinical trial, involving about 64,500 post-menopausal women 50 to 79; and a community prevention study to encourage healthful behaviors among women of all ages and socioeconomic backgrounds.
The AMA supports increased funding for women's health research and inclusion of both genders in medical studies.
Results of medical testing conducted exclusively on men should not be generalized to women without evidence that it applies equally to both genders, stated AMA policy adopted in 1990.
It's also important to ascertain to what extent gender disparities in medical care are a result of biological differences between the sexes, and "to what extent utilization practices and physician-patient interactions are influenced by cultural and social conceptions of gender," AMA policy states.
More is known about gender differences involving the heart than any other organ, said cardiovascular researcher Dr. Marianne J. Legato, director of the Partnership for Women's Health at Columbia University. The collaborative research and educational program, which began in February, is focusing on gender-specific research and educating physicians and the public about gender differences.
Research has found that treatment outcomes vary and are related to the gender of the patient. For example, women are more likely to die after using certain heart medications, such as anti-arrhythmia drugs. And while aspirin reduces the risk of stroke in men with high blood pressure, it doesn't do the same for women.
"We need to figure out what makes men and women different in their responses, and design therapies that are appropriate to the disease and the gender of the person," said Dr. Michael Rosen, an associate director of the Partnership for Women's Health.