To report the prevalence of lipid and nonlipid coronary artery disease risk factors in women classified by use of oral contraceptives or sex hormone replacement therapy.
A population-based cross-sectional survey in nine Canadian provinces (not including Nova Scotia) between 1988 and 1992 invited 13,506 women aged 18 to 74 years to participate. During a clinic visit after a home interview, a blood sample was obtained following a fast of 8 h or more from 8637 women.
Fasting plasma total cholesterol, triglycerides, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, blood pressure, smoking status, self-reported diabetes, and self-reported use of oral contraceptive or sex hormone replacement therapy pills.
The prevalence of oral contraceptive use was 41% for women 18 to 24 years old and 20% for women 25 to 34 years old. The prevalence of sex hormone replacement therapy was 4% for women 35 to 44 years old, 20% for women 45 to 64 years old and 11% for women 65 to 74 years old. Users of sex hormone replacement therapy aged 35 to 44 years had slightly higher mean LDL cholesterol than nonusers (3.04 versus 2.89 mmol/L). Users and nonusers aged 45 to 54 years had similar LDL cholesterol levels, and users aged 55 to 64 and 65 to 74 years had lower LDL cholesterol and higher HDL cholesterol levels, respectively, than nonusers. Triglyceride levels were higher in oral contraceptive users and in younger women on sex hormone replacement therapy than in nonusers. In the general population of Canada the use of oral contraceptives in women less than age 35 years had only a marginal effect on the prevalence of lipid and nonlipid risk factors. Women aged 18 to 24 years using oral contraceptives had a higher mean LDL cholesterol level of 2.73 versus 2.35 mmol/L for nonusers. The prevalence of lipid and nonlipid risk factors in women using sex hormone replacement therapy increased slightly for those aged 35 to 54 years and decreased in women aged 55 to 74 years. A lower percentage of women using sex hormone replacement therapy, aged 55 to 74 years, had high risk LDL cholesterol levels (21% versus 36% for nonusers). A larger percentage of women using sex hormone replacement therapy had low risk HDL cholesterol levels (54% versus 29% for nonusers). The nonlipid risk factor profile for women aged 35 to 54 years on sex hormone replacement therapy was less favourable than for nonusers: obesity was more common (36% versus 28%, respectively), hypertension was higher (22% versus 12%, respectively), and the proportion of women with one or more nonlipid risk factors was higher. The nonlipid risk factor profile for women 55 to 74 years of age who were using sex hormone replacement therapy was more favourable than for nonusers: obesity was lower (31% versus 47%, respectively), smoking was lower (7% versus 16%, respectively), sedentary behaviour was lower (28% versus 37%, respectively), and fewer women had two or more of these risk factors (31% versus 52%, respectively).
The findings suggest that women at higher risk for coronary artery disease tend to have a lower prevalence of use of sex hormone replacement therapy.