To report on the impact of different blood lipid evaluation and treatment guidelines on the proportion of Canadians identified and treated for high blood cholesterol.
The Canadian Heart Health Surveys were carried out in Canada between 1986 and 1991. The data used in this study were from cross-sectional probability samples of adults aged 18 to 74 years, gathered in four provincial health surveys (Quebec, Alberta, Manitoba and Ontario) between 1989 and 1992, which obtained information on family history of heart disease. Data reported are for 7238 subjects fasting 8 h or more and providing a blood sample. All blood lipid analysis were done at the J Alick Little Lipid Research Laboratory, University of Toronto, which is standardized according to the National Heart, Lung, and Blood Institute, Centers for Disease Control (Atlanta) Lipid Standardization Program.
With respect to the four guidelines examined--the Canadian Consensus Conference on Cholesterol (CCCC), 1987; the Toronto Working Group on Cholesterol Policy (TWG), 1990; the Canadian Task Force on the Periodic Health Examination (PHE), 1993; and the National Cholesterol Education Program (NCEP), 1993, in the United States--a comparison of the proportion of individuals in the population for whom a lipid profile was constructed, and who were prescribed a diet and drug therapy under different assumptions of success with dietary therapy for each guideline.
Major differences were observed in the impact of the various guidelines with respect to the percentage of subjects who were tested, provided with a lipid profile, and eligible for diet and/or drug therapy. In general the percentages in each group were higher for the CCCC and the NCEP guidelines than for the PHE and TWG guidelines.
The divergent results obtained from the application of the various guidelines are cause for concern and explain in part the confusion that surrounds the topic of blood cholesterol in public health and clinical contexts. Public health policy in the area of cardiovascular disease prevention would benefit from explicit consideration of various types of criteria for formulation of identification and treatment guidelines.
Comment In: Can J Cardiol. 1999 Apr;15(4):407-810322249
Fasting plasma cholesterol and triglyceride concentrations were determined for 6407 working Canadian adults aged 20 to 69 years in Toronto and Hamilton. Means, medians and 5th and 95th percentiles were ascertained from the data for men, women taking oral contraceptives or estrogen preparations, and women not taking such medication. Mean plasma cholesterol values (mg/dL) ranged in men from 168.3 at ages 20 to 24 years to 211.5 at ages 45 to 49 years, and in women using hormone preparations from 180.3 at ages 20 to 24 years to 224.2 at ages 50 to 54 years; corresponding values in women not using these preparations were 164.9 and 220.6. Plasma triglyceride means (mg/dL) ranged in men from 108.7 at ages 20 to 24 years to 166.7 at ages 40 to 44 years, in women using hormone preparations from 115.4 at ages 20 to 24 years to 145.3 at ages 45 to 59 years, and in women not using these preparations from 77.5 at ages 20 to 24 years to 112.4 at ages 50 to 54 years.
To report reference values for plasma lipids and lipoproteins in Canadian adults and the prevalence in the population of various levels of risk for coronary artery disease from dyslipoproteinemia.
Population- based provincial heart health cross-sectional surveys in 10 provinces between 1986 and 1992 invited 29,855 men and 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 18,555 people. Plasma lipid levels were determined at the J Alick Little Lipid Research Laboratory, Toronto, with standardization of the Centers for Disease Control Lipid Standardization Program, Atlanta.
Fasting plasma total cholesterol, triglyceride, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and non-HDL-C levels.
Mean plasma total cholesterol, LDL-C, non-HDL-C and triglyceride levels increased with age in men to a peak at around age 54 years, while in women the increases were more gradual at a lower level until age 54 years, after which they increased appreciably eventually exceeding values for men. A high percentage of adults were at increased risk for coronary artery disease: 44% had elevated total cholesterol levels above 5.2 mmol/L; 14% had LDL-C levels above 4.1 mmol/L; 8% had HDL-C values below 0.9 mmol/L; and 14% had triglyceride levels above 2.3 mmol/L. Eleven per cent of adults had both total cholesterol level above 6.2 mmol/L and LDL-C level above 4.1 mmol/L.
The high prevalence of Canadian adults at risk because of elevated plasma lipid levels strongly indicates the need for comprehensive public health programs to reduce plasma lipid levels in the population and the need to encourage physicians to treat those at high risk.
Comment In: Can J Cardiol. 1999 Apr;15(4):407-810322249
To report population reference values for blood lipids, to determine the prevalence of lipid risk factors and to assess their association with other risk factors.
Population-based cross-sectional surveys. Survey participants were interviewed at home and provided a blood sample at a clinic. All blood lipid analyses were done in the Lipid Research Laboratory, University of Toronto. The laboratory is standardized in the National Heart, Lung Blood Institute-Centres for Disease Control Standardization Program.
Nine Canadian provinces, from 1986 to 1990.
A probability sample of 26,293 men and women aged 18 to 74 was selected from the health insurance registers for each province. Blood samples were obtained from 16,924 participants who had fasted 8 hours or more.
Concentration of total plasma cholesterol, triglycerides and high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol in blood samples from fasting participants.
Of the study population, 46% had total plasma cholesterol levels above 5.2 mmol/L, 15% had LDL-cholesterol levels above 4.1 mmol/L, 15% had triglyceride levels above 2.3 mmol/L and 8% had HDL-cholesterol levels below 0.9 mmol/L. Total plasma cholesterol, LDL-cholesterol and triglyceride levels rose with age in men to a maximum in the 45-54 age group; in women there was little change with age up to ages 45 to 54, at which time the level of each of these lipids increased appreciably. The age-standardized prevalence of obesity was positively associated with elevation of total plasma cholesterol.
The results suggest the need for a multifactorial approach in health promotion efforts to lower blood cholesterol levels and reduce other risk factors in the population. A considerable number of adults were found to be at risk at all ages in both sexes. In the short term, men aged 34 and older and women aged 45 and older might benefit most from prevention programs.
The lipids and lipoproteins - cholesterol (C), triglyceride (TG) and high-density, low-density, very-low-density and sinking pre-beta-lipoprotein cholesterol (HDL-C, LDL-C, VLDL-C and SPB-C) - in plasma samples from 1620 fasting white adults and children from the Toronto-Hamilton area were analysed. The mean concentration of HDL-C was about 45 mg/dl in men and about 60 mg/dl in women, and the levels were constant throughout adult life in both sexes. Boys had higher mean HDL-C levels than men, but girls had lower mean HDL-C levels than women. Mean LDL-C levels, like total C levels, increased with age, from about 87 mg/dl in boys to 136 mg/dl in men, and from about 91 mg/dl in girls to 145 mg/dl in women. The mean levels of VLDL-C followed the TG patterns for age and sex, rising from about 7 mg/dl in boys to 26 mg/dl in men, and from about 11 mg/dl in girls to 19 mg/dl in women. SPB-C was detectable visually in 39% of the population and with the aid of densitometry in 54%; the levels were not related to age, sex or oral contraceptive use, and the median level was 3 mg/dl.Prevalence estimates of hyperlipoproteinemia showed that type IV was the most common, and it was found more than three times as often in men as in women. This was in part due to the customary use of plasma TG cut-off points that do not reflect the large difference in TG levels between males and females. Type IIA hyperlipoproteinemia was found in about 2% of the adults and type IIb in a further 1%. Types I, III and V were all rare. The prevalence of types II and IV hyperlipoproteinemia was four times greater in women using oral contraceptives than in nonusers in the same age range.
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Prevalence of high plasma triglyceride combined with low HDL-C levels and its association with smoking, hypertension, obesity, diabetes, sedentariness and LDL-C levels in the Canadian population. Canadian Heart Health Surveys Research Group.
To report the associations of plasma triglyceride, high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) with nonlipid coronary artery disease risk factors. In particular, the associations for persons with high triglyceride and low HDL-C levels were examined.
A stratified random probability sample of 29,855 men and women aged 18 to 74 years from the Canadian Heart Health Surveys (1986 to 1992) in 10 provinces. Blood samples were obtained from 18,555 participants who had fasted for 8 h or more. Plasma lipids were determined at the J Alick Little Lipid Research Laboratory, Toronto, Ontario, with standardization of the Centers for Disease Control Lipid Standardization Program, Atlanta.
Fasting plasma total cholesterol, triglyceride, LDL-C and HDL-C levels.
The prevalence of men with triglyceride levels above 1.7 mmol/L and HDL-C levels below 0.9 mmol/L was 10%, compared with 3% for men with triglyceride levels below 1.7 mmol/L and HDL-C levels below 0.9 mmol/L. The prevalence of women with triglyceride levels above 1.7 mmol/L and HDL-C levels below 0.9 mmol/L was 3% compared with a prevalence of less than 1% for women with triglyceride levels below 1.7 mmol/L and HDL-C levels below 0.9 mmol/L. Even when plasma LDL-C was low at less than 3.4 mmol/L, there was an age trend for increasing prevalences of the combination of triglyceride levels 2.3 mmol/L or greater and HDL-C levels less than 0.9 mmol/L in both sexes. The prevalence of a triglyceride levels 2.3 mmol/L or greater combined with an HDL-C level below 0.9 mmol/L was increased in groups who were cigarette smokers, diabetic, hypertensive, obese or sedentary, or who had higher LDL-C levels in both sexes, and the increase was even greater in the presence of two or more of these other risk factors.
Among men or women with low HDL-C and high triglyceride levels, smoking, diabetes, sedentariness, hypertension and obesity were much more prevalent than among those at low risk with high HDL-C and low triglyceride levels.
The prevalence of hyperlipidemia in women and its association with use of oral contraceptives, sex hormone replacement therapy and nonlipid coronary artery disease risk factors. Canadian Heart Health Surveys Research Group.
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.