Objective: To determine why women have a higher mortality rate than men when undergoing coronary artery bypass grafting.
Design: Retrospective analysis of patients entered in a mandatory state database.
Participants: 19,224 patients who underwent coronary artery bypass grafting in New York State in 1995.
Method: The authors evaluated data pertaining to 27 variables. They conducted univariate analysis using the Student t test for continuous variables and the chi-square test or the Fisher exact test for discrete data. They conducted multivariate analysis using a logistic regression model.
Results: Analysis of body surface area revealed that smaller size was a risk factor for both women and men. Analysis of age demonstrated increased risk for mortality in women in both older and younger subpopulations. Other significant variables included a lesser degree of revascularization and less frequent use of the internal mammary artery in women.
Conclusion: Smaller size and advanced age alone do not explain why female gender is an independent risk factor for mortality from coronary artery bypass grafting. Increased mortality is probably due to the fact that women have more comorbid conditions than men at the time of referral, perhaps because they are not being evaluated aggressively enough.