Sex differences in cardiac catheterization after acute myocardial infarction: The role of procedure appropriateness

Background: many studies have found that women are less likely than men to have cardiac catheterization after an acute myocardial infarction; however, it is unknown whether sex differences reflect inappropriate treatment. Objective: To ascertain whether cardiac catheterization use after acute myocardial infarction in men and women varied by sex and the appropriateness of the procedure, as determined by clinical guidelines. Design: Retrospective analysis of chart-abstracted data. Setting: U.S. acute-care hospitals. Patients: 143 444 Medicare patients who were hospitalized for acute myocardial infarction between 1994 and 1996. Measurements: Cardiac catheterization use within 60 days of hospitalization for acute myocardial infarction. Results: Women had lower crude rates of cardiac catheterization than men (35.7% for women vs. 46.5% for men [P < 0.001]; difference, 10.8 percentage points). Multivariable adjustment for demographic, clinical, and hospital characteristics reduced most of the sex differences in procedure use (risk-standardized rates, 40.3% for women vs. 41.9% for men [P < 0.001]; difference, 1.6 percentage points), Sex differences in cardiac catheterization use varied by the appropriateness of the procedure. Risk-standardized rates of cardiac catheterization were similar for men and women with strong indications for the procedure (44.1% for women vs. 44.6% for men [P > 0.2]; difference, 0.5 percentage point). Rates of cardiac catheterization use among patients with weak indications did not significantly differ between men and women (16.5% for women vs. 18.0% for men [P = 0.096]; difference, 1.5 percentage points). Sex differences in cardiac catheterization use were largest for patients with equivocal indications (39.4% for women vs. 42.5% for men [P < 0.001]; difference, 3.1 percentage points). Conclusions: Among elderly persons, women have lower rates of cardiac catheterization use after an acute myocardial infarction than men. However, this difference was attenuated after multivariable adjustment, and it occurred primarily in patients with equivocal indications. We found no sex variations in procedure use among patients who had strong indications for cardiac catheterization.