Assessment of Analysis by Gender in the Cochrane Reviews as Related to Treatment of Cardiovascular Disease

BACKGROUND: Cardiovascular disease (CVD) is the leading killer of women in the United States, yet medical care is often based on evidence from clinical trials performed predominantly with men. Numerous studies show that CVD risk factors, clinical presentation, treatment, and treatment outcomes can vary between men and women. METHODS: The Cochrane Library maintains a large database of critically appraised evidence including meta-analyses of clinical trials, called Systematic Reviews. There were 30 Systematic Reviews pertaining to the treatment of CVD published collectively by the Cochrane Heart Group, Hypertension Group, and Peripheral Vascular Diseases Groups at the time of our study. We examined these 30 Systematic Reviews and the great majority of the clinical trials used for their meta-analyses for inclusion of women and gender-based data analyses. Women comprised only 27% of the pooled population of 258 clinical trials. RESULTS: Of those trials that included both men and women (n = 196), only 33% examined outcomes by gender. In trials that performed a gender-based analysis, 20% reported significant (p < 0.05) differences in cardiovascular-related outcomes by gender. CONCLUSIONS: We conclude that (1) there are not enough large-scale clinical trials or meta-analyses concerning CVD in women to determine if their medical treatment should differ from that of men, (2) all clinical trials relating to CVD treatment should have significantly more female participants, and gender-based analyses should be performed, as currently recommended for National Institutes of Health (NIH)-sponsored research by the NIH Revitalization Act of 1993, and (3) the Cochrane Library would be a more useful tool for the evidence-based healthcare of women if the Systematic Reviews used all available gender-specific information in their analyses.