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Although coronary artery disease (CAD) is the leading cause of death for women in the United States, treatment studies to date have primarily enrolled men and may not reflect the benefits and risks that women experience. Our systematic review of the medical literature assessed the comparative effectiveness of major treatment options for CAD specifically in women. The comparisons were (1) percutaneous coronary intervention (PCI) versus fibrinolysis/supportive pharmacologic therapy in ST elevation myocardial infarction (STEMI), (2) early invasive versus initial conservative management in non-ST elevation myocardial infarction (NSTEMI) or unstable angina, and (3) PCI versus coronary artery bypass surgery (CABG) versus optimal medical therapy in stable or unstable angina. The endpoints assessed were clinical outcomes, modifiers of effectiveness by demographic and clinical factors, and safety outcomes.
MEDLINE®, PubMed®, Embase®, and Cochrane Database of Systematic Reviews.
Randomized controlled trials published in English from January 1, 2001, to December 12, 2011, comparing the treatment options for CAD listed above and containing sex-specific outcomes. Clinical outcomes were classified as short term (≤30 days), intermediate term (1 year), or long term (>1 year). Random-effects meta-analysis was performed for studies with similar outcomes measured at similar time points.
Twenty-eight comparative studies contributed evidence about effectiveness, modifiers of effectiveness, or safety for the comparisons described above. For women with STEMI, five studies showed a reduction in composite outcomes (primarily death/MI/stroke) at 30 days for PCI over fibrinolysis (odds ratio [OR] 0.50; 95% CI, 0.36 to 0.72; high strength of evidence [SOE]); there was insufficient evidence for assessing outcomes at 1 year. For women with NSTEMI or unstable angina, the included studies, although not showing statistical significance, suggested a benefit of early invasive over initial conservative management for the composite outcome of primarily death/MI at 6 months and 1 year (2 studies, OR 0.77; CI, 0.28 to 2.12; low SOE; 5 studies, OR 0.78; CI, 0.54 to 1.12; low SOE). Evidence, however, suggested a small benefit of initial conservative management at 5 years (2 studies, OR 1.05; CI, 0.81 to 1.35). Given the small suggested benefit at 5 years, the wide confidence interval crossing 1, and the trend favoring early invasive therapy suggested at earlier time points and across time points in men--we cannot support firm conclusions (insufficient SOE). For women with stable angina randomized to revascularization (PCI or CABG) or medical therapy, three studies showed a reduction in the composite outcome of death/MI/repeat revascularization at 5 years for revascularization with either PCI (OR 0.64; CI, 0.47 to 0.89; moderate SOE) or CABG (OR 0.56; CI, 0.32 to 0.96; low SOE). For stable and unstable angina trials comparing PCI with CABG, two studies suggested a nonsignificant benefit of PCI in mortality at 30 days (low SOE). At 1 year and beyond, although suggestive of a benefit of CABG in for the composite outcomes of death/MI/stroke for women, this finding was not statistically significant and represented wide confidence intervals (low SOE at 1 year and at >2 years).
Five studies assessed modifiers of effectiveness in women due to demographic factors (≥65 or ≥80 years of age) or clinical factors (risk stratification or diabetes). Strength of evidence for modifiers of effectiveness for STEMI, NSTEMI, and stable/unstable angina was insufficient.
Four studies assessed safety outcomes in women: two STEMI studies (PCI versus fibrinolysis) and two NSTEMI studies (PCI versus CABG) assessed transfusion rates, incidence of intracranial hemorrhage, and bleeding rates. Strength of evidence for safety outcomes for all the CAD presentations was insufficient.
From a limited number of studies reporting results for women separately from the total study population, our findings confirm current practice and evidence for care in one of the three areas evaluated. For women with STEMI, we found that an invasive approach with immediate PCI is superior to fibrinolysis for reducing cardiovascular events, which is similar to findings in previous meta-analyses combining results for both women and men. For women with NSTEMI or unstable angina, evidence suggested that an early invasive approach reduces cardiovascular events; however, it was not statistically significant. Previous meta-analyses of studies comparing early invasive with initial conservative strategies on a combined population of men and women showed a significant benefit of early invasive therapy. We also found that the few trials reporting sex-specific data on revascularization compared with optimal medical therapy for stable angina showed a greater benefit with revascularization for women, while the men in the study fared equally well with either treatment. In contrast, previous meta-analyses that combined results for men and women found similar outcomes for either treatment.
Limitations include a small number of trials with data for women available for meta-analysis, varying definitions of composite outcomes, and variable timing of followup. Future studies should collect and report clinical outcomes and harms in women by treatment strategy and at each followup time point--including subgroup data on important demographic and clinical factors that may modify clinical effectiveness--so that firmer conclusions can be reached about the risk and benefit of these therapies in women.