Young women with acute MI have higher rates of in-hospital mortality compared with young men, which may be due in part because young men with coronary heart disease (CHD) are more likely to die outside the hospital walls, according to study results published July 1 in the American Journal of Cardiology.
CHD is the leading cause of death for both men and women in the U.S. “Although women, on average, develop their first acute MI about 10 years later than men and, overall, are less likely to develop MI than are men, several studies have shown that young women have greater in-hospital mortality than young men,” the authors wrote.
To further expand on data, Yu-Hsuan Shao, PhD, from the University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School in New Brunswick, N.J., and colleagues analyzed a cohort of 423,067 patients (247,701 men and 175,366 women) treated at nonfederal N.J. hospitals to compare out-of-hospital CHD death rates for both men and women.
From 1990 to 2004, there were 355,569 CHD deaths in the state and data were obtained from the MI Data Acquisition System (MIDAS). During the study, authors set out to explore whether or not the reason women had increased rates of death after MI was due to the fact that more young men may die from CHD outside the hospital walls.
The researchers looked at four groups: patients aged 35 to 54, 55 to 64, 65 to 74 and 75 years or older. Researchers stratified by age and adjusted each group for gender, race, diabetes, hypertension, renal disease, anemia, cancer, cerebrovascular disease, complications, year of admission and site of MI to make the association between gender and mortality.
After stratification, results showed that patients aged 35 to 54 were more likely to have comorbitidies including diabetes, hypertension and anemia during their hospital stay. Women consisted of 21 percent of the patients admitted to the hospital for MI in the 35- to 54-year-old group and accounted for 45 percent of the patients in the 55 and older group.
These data also showed that younger women were more likely to undergo invasive cardiac procedures such as cardiac cath, PCI or CABG than young men. While in-hospital mortality rose as age did, women had a greater incidence of in-hospital mortality compared to men in all four groups.
Additionally, results showed that the odds ratio for in-hospital mortality for women was 1.64 in the 35- to 54-year age group and 1.09 for the 75 and older age group. The adjusted odds ratio rates for mortality at 28 days was 1.39 in the youngest age group compared to men in the same group.
Overall, woman had a lower rate of out-of-hospital CHD-related deaths compared to men, 11 per every 100,000 versus 55 per every 100,000. Younger women were four times less likely than men to be hospitalized for MI (78 versus 297 per 100,000) and half as likely to die from MI in hospital (seven versus 17 per 100,000).
“Women had greater adjusted odds ratios for in-hospital mortality but lower odds ratios for out-of-hospital CHD death than men,” the authors wrote.
During the 15-year period of the study, results showed that in-hospital death rates declined by 60 percent for men and 66 percent for women in the 35- to 54-year age group. During that time, out-of-hospital CHD deaths were higher for men compared to women, 28.4 percent versus 10 percent, respectively. Between 1990 and 2004, the risk of in-hospital death compared to out-of-hospital death decreased from 0.34 to 0.19 for men and 0.71 to 0.27 in young women.
“Gender difference with respect to in-hospital versus out-of-hospital death decreased with time,” the authors wrote. “This resulted from the more pronounced decrease of in-hospital case fatality among young women and the decrease in out-of-hospital death among young men.”
While the authors said that reasons for the worse outcomes of MI in younger women are still unknown, evidence suggests that it may be due to in-hospital complications and a greater incidence rate of comorbidities.
“In-hospital mortality improved more in young women than in young men, and out-of-hospital deaths decreased primarily in young men. These trends resulted in attenuation of the differences between young men and young women,” Shao and colleagues concluded.