Clinical Factors Explain Differences in Frequency of Cardiac Procedures between Men and Women after Cardiac Catheterization

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The summary below is from the full report titled "Sex Differences in Access to Coronary Revascularization after Cardiac Catheterization: Importance of Detailed Clinical Data." It is in the 21 May 2002 issue of Annals of Internal Medicine (volume 136, pages 723-732). The authors are WA Ghali, PD Faris, PD Galbraith, CM Norris, MJ Curtis, LD Saunders, V Dzavik, LB Mitchell, and ML Knudtson, for the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) Investigators.

What is the problem and what is known about it so far?

Studies have shown that men get more tests and treatments for heart disease than do women. Possible explanations for these differences are that men may have more severe disease than women or that prejudice may lead doctors to offer more tests and treatments to men than to women. Cardiac catheterization is a test in which doctors inject dye into a patient's circulatory system to look for blockages in heart blood vessels and for poor heart function. Options for treating patients with blocked heart blood vessels include medication or revascularization procedures to open the vessels or bypass the blockages. Previous studies have not had enough information to determine whether differences between the sexes in the severity of heart disease explain the observed discrepancy in procedure rates between men and women.

Why did the researchers do this particular study?

To compare the frequency of revascularization procedures in men and women who had equally severe heart disease.

Who was studied?

21,816 patients who had cardiac catheterization in Alberta, Canada, during 1995 to 1998.

How was the study done?

The researchers collected information on the numbers of revascularization procedures done in the year after cardiac catheterization. Then, they compared the frequency with which this procedure was performed in men versus women. The researchers did this by using three different levels of statistical adjustment to equalize factors that might influence the decision to offer treatment. First, they did not account for any patient factors. Next, they accounted for general factors, such as age and previous heart disease. Finally, they accounted for the severity of disease seen on catheterization.

What did the researchers find?

Before patient factors were considered, women appeared much less likely than men to get revascularization procedures. Adjustment for general factors did not change this result. However, when the researchers accounted for the severity of heart disease, they found that men and women with similar severity of heart disease received procedures with similar frequency.

What were the limitations of the study?

These results may not apply to men and women in other geographic areas. Moreover, this study included only patients who had cardiac catheterization, so it does not tell us whether men and women who present with similar symptoms get cardiac catheterization at different rates.

What are the implications of the study?

After cardiac catheterization, men get revascularization procedures more often than women do; however, this difference apparently is explained by more severe heart disease in men rather than by bias of doctors against women. Studies comparing the use of cardiac procedures in different groups should adjust for severity of disease.