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More gender-specific research is needed to improve poorer outcomes for women
Cardiovascular disease (CVD) is the single most common cause of death in women and men. Despite widespread assumptions to the contrary, women have accounted for more than one-half of the almost 1 million deaths due to heart disease and stroke in the United States annually since 1984. Women, compared to men, especially those under the age of 50 years, experience higher rates of recurrent myocardial infarction, heart failure and mortality after a first myocardial infarction, and are more likely to be misdiagnosed or diagnosed late in the course of their illness.
Annual hospitalizations and mortality for heart failure and total CVD expenditures are greater for women than men. While mortality from cardiovascular diseases has significantly declined over the past three decades, women have not experienced the same reductions in death and disability as have men. This significant gender-related mortality gap persists due to a combination of low awareness, misconceptions by physicians and women, gender-based physiologic differences, and disparities in care.
LESS THERAPY FOR WOMEN
The underlying causes for these disparities are multifactorial and the solutions complex. Gender-based disparities in preventive, diagnostic and therapeutic interventions are present on multiple levels. Women receive fewer cardiac diagnostic evaluations and less intensive therapy, from preventive interventions, to revascularization procedures to aspirin prescriptions. Even after a diagnosis of heart disease, gender-based differences in provision of care are present.
Women hospitalized with myocardial infarction are more likely than men to be managed by generalists, rather than referred for cardiology consultation, and are less likely to be transferred from community hospitals to centers for advanced care-practices associated with poorer short-term outcomes.
There is also a growing body of literature documenting important biologic gender differences in CVD that may impact clinical care delivery. There are obvious differences due to the effects of gonadal hormones. However, differences in symptoms, accuracy of diagnostic tests, response to therapy, prevalence and relative risk of cardiovascular risk factors, as well as social and behavioral issues have all been identified. It is not always apparent whether or not these differences warrant a variation in established practice.
Many early cardiovascular clinical trials routinely exclude women or make no effort to enroll women in sufficient numbers to draw gender-based conclusions. With few exceptions, women currently make up only 20% to 30% of participants in cardiovascular clinical trials. Even when women are included as research subjects, it is often difficult to determine their outcomes from published reports. Only a quarter of recent cardiovascular trial results published in major U.S. internal medicine and cardiology journals reported gender-specific outcomes.
The lack of relevant research in women has resulted in a substantial and persistent gender-based knowledge gap about everything from the symptoms of heart attack in women, to the risks and benefits of commonly used cardiovascular diagnostic tests and therapies. Better evidence from properly designed research studies can better serve women with CVD.
An important example is the National Heart, Lung and Blood Institute (NHLBI)-funded multi-center Women's Ischemic Syndrome Evaluation (WISE) study of approximately 900 women who underwent coronary angiography for chest pain symptoms and a multitude of other investigations designed to better characterize ischemic heart disease in women. We have already learned a great deal from numerous WISE publications that have underscored the value of gender-specific research and fundamentally changed the understanding of chest pain, CVD risk factors, vascular function, hormone interactions and atherosclerosis in women.
Cardiovascular clinical trial design must include women in adequate numbers to provide gender-specific data, and that data must be analyzed and reported by gender.
Systemic contributions to differences in cardiovascular care for women also include physician practice and referral patterns. In the United States, many women receive all or most of their medical care from specialists in obstetrics and gynecology during their reproductive years and continue those relationships well past menopause, or until a significant non-gynecologic illness occurs. Traditionally, there has been a greater focus on reproductive and breast health than on other health risks, and less awareness and self efficacy among these specialists about early cardiovascular risk identification and treatment.
RISK FACTORS ON THE RISE
The rise in risk factor prevalence in younger women, especially smoking, obesity and diabetes, has led to a growing number of individuals at high risk who do not look like typical heart patients. Reducing women's future burden of CVD will depend heavily on improved preventive measures which currently fall short of recommendations. Simply taking what has been proven effective, and widely and appropriately applying it to women, can markedly improve care and outcomes.
Critical to this effort is continued education about women's cardiovascular risks, symptoms and the use of appropriate diagnostic tests and therapies.
The most recent guideline, published in 2007 by the American Heart Assn. and endorsed by multiple professional and patient organizations, has simplified the risk assessment and decision-making process for easier implementation in daily practice.
The guidelines encourage clinicians and patients to focus on reducing long-term, rather than 10-year CVD risk. With few exceptions, those therapies that have been shown efficacious in men also prevent CVD in women and should be recommended to women at risk.
Sharonne Hayes, MD, FACC, is the director of the Mayo Clinic Women's Heart Clinic and associate professor of medicine for the Mayo Clinic College of Medicine.