Gender bias in treatment of cardiovascular disease in Newfoundland and Labrador

Abstract

Rationale: Cardiovascular disease (CDV) is the leading cause of mortality and morbidity in Canada. Mortality from cardiovascular disease is higher in Newfoundland and Labrador (NL) than other Canadian provinces. Gender differences in the treatment of and assessment of CVD have been repeatedly demonstrated in clinical trials. -- Objective: 1) To determine the existence and impact of gender bias in the treatment of Acute Myocardial Infarction (AMI) in NL. 2) To determine if male gender is associated with inappropriate use of surgical revascularization in NL. -- Design: Two observational studies: 1) Prospective cohort study; 2) Cohort study with retrospective data collection. -- Setting: University based tertiary referral center in St. John's, NL. -- Participants: 1) AMI patients admitted between May 24, 1990 and June 30, 1993 and followed for 3 years. -- 2) Patients referred for Coronary Angiography (CA) between April!, 1994 and March 31, 1995 who subsequently underwent Coronary Artery Bypass Grafting (CABO). -- Measurements: 1) The gender rates of risk factors, post-MI complications, CA, pharmacologic interventions, CABO, Percutaneous Transluminal Coronary Angioplasty (PTCA), functional class assessment using Goldman scales and mortality for three years following AMI were compared. -- 2) CAD risk factors, angina severity, coronary anatomy, medical therapy, CABO indication, appropriateness and necessity of CABO and operative risk and post operative complications were compared by gender. -- Results: 1) During the AMI admission 9.4% of women compared to 3.9% of men had recurrent MI (p=0.04), 12.6% of women and 7.4% of men died (p=0.03). With the exception of heparin (67% male vs. 58% female p = 0.02), pharmacologic intervention was comparable in men and women. CA was performed in 31 % of women and 41.9% of men (p = 0.007). Men were more likely to be revascularized during the AMI admission (19.3 vs. 12.2, p= 0.02) but there was no gender difference in revascularization up to three years post-MI. Multiple logistic regression analysis (MLR), which included demographic and clinical characteristics, revealed that male sex was a strong predictor of CA and revascularization post-MI. During follow-up women consistently reported a statistically significant reduced functional capacity. Survival analysis revealed that women had significantly reduced likelihood of survival (p=0.004) independent of age and Angiotensin Converting Enzyme (ACE) inhibitor therapy. -- 2) Although there was no gender difference in angiographic findings of patients referred for CABG, 88.5% of women compared to 78.90,4, of men were referred for CA due to Class IV angina (p=0.006) and 49.9% of women versus 30.1% of men were at moderately to very high operative risk (p=0.000). CABO was deemed highly appropriate in 96.8% of women versus 99.5% of men (p=0.066) and highly necessary in 92.7% of women versus 94.2% of men (p=0.66). -- Conclusions: 1) In Newfoundland and Labrador, Canada, despite more complicated post-MI courses, women were as likely as men to receive standard pharmacologic intervention but significantly less likely to undergo CA and revascularization following AMI. -- 2) Furthermore women referred for CABO had more advanced and severe CHD than men. It is possible that gender bias in the utilization of coronary revascularization may contribute to excess CHD mortality observed in women. -- Caution must be exercised in generalizing the results of these studies of highly selected populations to the overall population of NL.