In one of the largest and most comprehensive studies to date of the care received by elderly patients suffering an acute myocardial infarction, University of Washington researchers have revealed gender-based differences in early, in-hospital management.
Women are less likely to receive early treatment following a heart attack and are more likely to be assigned a do-not-resuscitate order during their hospital stay. Overall, however, most of the treatment differences are small and there is no apparent effect on 30-day mortality rates.
The New England Journal of Medicine is publishing the findings of the Medicare Cooperative Cardiovascular Project in its July 6 issue. The project analyzed the care received by nearly 140,000 Medicare participants throughout the United States who suffered a heart attack from 1994 to 1995. Forty-nine percent of the participants were women. The study addressed limitations in smaller projects that have suggested women receive less aggressive post-acute myocardial infarction care then men.
Female patients were 26 percent more likely to receive a Do Not Resuscitate (DNR) order than their male counterparts. These women were, on average, older but less ill then men receiving a DNR order.
"This finding surprised us, and we found it quite concerning," said Dr. Leighton Chan, senior author of the study and assistant professor in the Department of Rehabilitation Medicine at the University of Washington School of Medicine. "Based on the data available to us, we were not sure if health care providers are more likely to recommend DNR status to women, or if women are simply more likely to request it. However, the assignment of DNR status is obviously critical to treatment decisions and patient outcome. Future work should really focus on this issue and ensure that women are being assigned DNR status appropriately after a heart attack."
Coronary artery disease is the leading cause of death in women 65 years of age and older, surpassing all forms of cancer combined. In 1992, two years prior to the study period, coronary artery disease accounted for 45 percent of deaths in this age group.
Statistically, women in this study group were significantly older, yet equal to men in the severity of their heart disease upon admission for treatment. Female patients in this study were more likely to have delayed seeking treatment for their symptoms and to have waited longer for medical attention—including 4 minutes longer for an initial electrocardiogram—after hospital arrival. The Medicare study revealed that women in all age groupings 65 years and older were less likely to undergo diagnostic cardiac catheterization and coronary arteriography. This gender discrepancy increased significantly with age. This finding is important because failure to employ cardiac catheterization as a diagnostic test has been previously associated with increased short-term mortality.
The research revealed other significant trends:
- Women were significantly less likely to receive aspirin, an effective and inexpensive treatment for acute myocardial infarction, at the time of discharge.
- Women were less likely to receive thrombolytic therapy and to receive it in an appropriately timely manner within the first hour after admission.
- Women were more likely than men to receive angiotensin converting enzyme (ACE) inhibitors; the significance of this finding, however, can not be determined from the current data set.
- Women were equally likely to receive beta-blocker therapy at the time of discharge.
Women in the study had a higher unadjusted 30 day mortality rate compared to men, 21 percent vs. 17 percent. However, after taking into account gender-differences in severity of illness, in-hospital treatments and other important prognostic indicators, the difference in 30-day mortality was not statistically significant.
The researchers emphasized the definition of "ideal candidates" for each intervention in their study. Most prior studies looking at gender differences in treatment after a heart attack failed to take into account whether the specific treatment was appropriate for the patient. This was a significant limitation. In the Medicare Cooperative Cardiovascular Project, however, each patient was defined as "ideal" for a particular treatment only if they met accepted criteria for an intervention and had no contraindications to its use. The researchers went on to calculate the percentage of male and female ideal candidates actually receiving a given intervention, then compared the adjusted male to female ratios.
Independent of gender differences, analysis of the treatment rates revealed several interventions that were significantly underutilized during the study period. Specifically, aspirin, an effective and inexpensive treatment for acute myocardial infarction, was prescribed for less than 80 percent of all ideal candidates (both men and women) at the time of discharge. It is estimated that full-utilization of aspirin therapy in appropriately selected individuals would prevent 3,000 deaths among Medicare patients annually.
"While this study highlights that women may be slightly less aggressively treated in the early stages of a heart attack," said Chan, "perhaps the more important story is the need for improvement in physicians' compliance with acute myocardial infarction practice guidelines. If we could get the "ideal" candidates for these interventions treated appropriately, both men and women would benefit."
The Division of Clinical Standards and Quality of the Health Care Financing Administration, Region 10, Seattle, performed the study in conjunction with the University of Washington. Three of the authors are affiliated with the University of Washington. Dr. Peter Houck and Richard MacLehose, MS, are on the clinical faculty of the Department of Epidemiology, part of the School of Public Health and Community Medicine.
Journal
New England Journal of Medicine