This listing provides a quick reference of some of the major research studies that have helped to advance what we know about women's health and health differences between men and women. There are a number of other studies, not listed on this page, that are also contributing to this knowledge. For a list of websites offering information on current research studies, click here.

Women's Health Initiative
The National Institutes of Health (NIH) established the Women's Health Initiative (WHI) in 1991 to address the most common causes of death, disability and impaired quality of life in postmenopausal women. The WHI is a long-term national health study that focuses on strategies for preventing heart disease, breast and colorectal cancer and osteoporosis in postmenopausal women. These diseases are the major causes of death and disability in older women of all races and socioeconomic backgrounds.

This 15-year project, sponsored by the National Institutes of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI), involves over 161,000 women aged 50-79. The WHI will attempt to address many of the inequities in women's health research and provide practical information to women and their physicians about hormone replacement therapy, dietary patterns and calcium/vitamin D supplements, and their effects on the prevention of heart disease, cancer and osteoporosis.

View the Women's Health Initiative Homepage.

Postmenopausal Estrogen/Progestin Interventions (PEPI)
The National Heart, Lung and Blood Institute (NHLBI), along with other units of the National Institutes of Health (NIH) launched the Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial in 1987. PEPI was conducted at seven research centers across the United States and followed 875 women for 3 years. At the start of the trial, the women were ages 45-64.

PEPI's main goal was to see what effects different types of hormone replacement therapy (the use of synthetic hormones estrogen and/or progestin) would have on increased cholesterol and high blood pressure, which are key risk factors for heart disease. The study looked at different forms of hormone replacement therapy including the use of estrogen alone and estrogen in combination with progestin or a placebo (sugar pill). PEPI also examined hormone replacement therapy's effects on bone mass (an indicator of osteoporosis risk) and quality of life.

Women's Ischemia Syndrome Evaluation (WISE)
Each year in the US 250,000 women die of ischemic heart disease, a condition characterized by decreased blood supply to the heart. Ischemia can be caused by atherosclerosis, a thickening and hardening of the walls of the blood vessels that supply the heart. Despite the fact that ischemic heart disease is the leading killer of women, it is diagnosed less often in women than men, and when it is diagnosed, it is usually at a later stage than men's and is treated less aggressively.

The Women's Ischemia Syndrome Evaluation (WISE) study, sponsored by the National Heart, Lung and Blood Institute, is a four-center study designed to address ischemia in women. Over 900 women will be enrolled in the study.

The WISE study is attempting to understand the best way to evaluate symptoms of ischemic heart disease in women and to optimize testing for the disease. The researchers will also try to understand why women have different symptoms then men and will look at the role of reproductive hormones (such as estrogen and progesterone) on symptoms and testing of the disease.

Nurses Health Study
In 1976, researchers at Harvard Medical School and Brigham and Women's Hospital mailed a two-page questionnaire to 175,000 registered nurses between the ages of 30 and 55. More than 120,000 were returned. This began the Nurses Health Study, one of the longest-running and largest studies of the risk factors for chronic diseases, such as cancer and diabetes, in women.

The researchers have resurveyed the group at 2-year intervals, each time asking new questions about the women's lifestyles and states of health. The answers have provided information on

• the role of diet and exercise in preventing disease
• the risks and benefits of hormone replacement therapy
• lifestyle behaviors (such as smoking and physical activity) that may put women at risk, or offer protection from adult-onset diabetes, heart disease, cancer and osteoporosis.

By now, the original members of the study are 55-75 years old. Researchers have recently recruited a second group of younger nurses to form the Nurses Health Study II to continue to study health questions that women face during their reproductive years.

HIV Viral Load Studies
A number of researchers have begun to study sex differences in HIV (Human Immunodeficiency Virus) and AIDS (Acquired Immune Deficiency Syndrome). HIV, the virus that causes AIDS, can exist in different amounts in the blood. The amount of the HIV in the blood is called the viral load. The level of the viral load is often used to determine when treatment should begin.

Recent studies have produced remarkable information on gender differences in the levels of HIV-1 (human immunodeficiency virus type 1) in infected individuals. One of the earliest and most important studies was from a team at Johns Hopkins University, School of Hygiene and Public Health. The study, released in 1998, showed differences in men and women in the HIV-1 viral load throughout the course of the disease. Although the length of time it took to progress from HIV to AIDS was similar for both men and women in the study, the women had lower HIV-1 viral loads throughout the course of progression.

Although the cause of this difference remains unclear, the information is important for the treatment of HIV. The guidelines for certain HIV treatments are set to begin when an infected individual reaches a certain viral load. Currently, the guidelines are the same for men and women. The results of this study suggest that women may need different treatment guidelines than men.

Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

The Prostate, Lung, Colorectal, and Ovarian Screening Trial is a large-scale study focusing on whether tests, that may detect cancers before symptoms develop, will reduce the number of deaths from these cancers. The study will involve 148,000 women and men aged 55 through 74 years at 11 medical facilities throughout the United States. The study includes the following tests for these diseases:

Ovarian Cancer

• physical examination of the ovaries
• blood tests for the tumor marker CA-125 ( a protein that is increased in the blood of many women with ovarian cancer
• transvaginal ultrasounds (an ultrasound test performed with a small instrument placed in the vagina)

Colorectal Cancer

• sigmoidoscopy (examination of the rectum and colon using a flexible lighted tube)

Lung Cancer

• chest x-rays

Prostate Cancer

• digital rectal exams

Visit the PLCO homepage for more in-depth information about the study.

Study of Tamoxifen and Raloxifene (STAR)
The Study of Tamoxifen and Raloxifene (STAR) is a clinical trial designed to see how the drug raloxifene (Evista®) compares with the drug tamoxifen (Nolvadex®) in reducing the rates of breast cancer in women who are at an increased risk of developing the disease. The study is primarily funded by the National Cancer Institute (NCI). The STAR trial is the first trial to compare a drug proven to reduce the chance of developing breast cancer with another drug that has the potential to reduce breast cancer risk. The study may help to give women more options for lowering their risk of breast cancer.

Researchers with the National Surgical Adjuvant Breast and Bowel Project (NSABP) are conducting the study at more than 400 centers across the United States, Puerto Rico, and Canada. The NSABP has a 40-year history of designing and conducting clinical trials. The results of their research has changed the way breast cancer is treated and, now, prevented.

Check out the National Cancer Institute's CancerTrials website for more information about the STAR trial.

Gender Differences in Response to Pain Relievers
Research supported by the National Institute of Dental and Craniofacial Research (NIDR) has revealed important differences in the way that men and women response to certain analgesics (pain relievers). The NIDR studies looked at men and women's responses to analgesics following wisdom tooth extractions. Investigators reported that kappa-opiods, a type of analgesic, produced significant pain relief following surgery in female patients but not in male patients.

Prior to these studies kappa-opiods were studied primarily in men. Because they provided little pain relief for men, they were thought to be ineffective at relieving pain. After women were included in studies on the drugs, researchers realized that the kappa-opiods did provide pain relief for women. The inclusion of women in these studies resulted in new pain relief options for women and highlighted the important role of gender in the body's response to certain medications.

The National Institute of Dental and Craniofacial Research website contains information on gender differences in pain and other conditions.

Fracture Intervention Trial (FIT)
Eight million American women have osteoporosis, a disease in which bones become fragile and more likely to break. In addition, 18 million Americans have low bone density, a risk factor for the disease. For this reason, studies on the prevention of osteoporosis and the related health problems are very important to our public's health. One such study, the Fracture Intervention Trial (FIT) is studying the effects of alendronate, a type of medication called an amino-bishphosphonate. Alendronate has been shown, in past studies, to increase bone density. This study examined alendronate's effect on the risk of fractures in women with low bone density.

Over 6000 women between the ages of 55-80 years participated in the Fracture Intervention Trial (FIT). All women in the study were diagnosed as having low bone density. The study found that the treatment increased bone density and reduced the risk of fractures. The study, sponsored by Merck Research Laboratories, is one of the largest intervention trials on osteoporosis. In conjunction with the FIT trial, additional studies are being conducted which will address a number of women's health issues.