Body mass index versus waist circumference as predictors of mortality in Canadian adults.

BACKGROUND: Elevated body mass index (BMI) and waist circumference (WC) are associated with increased mortality risk, but it is unclear which anthropometric measurement most highly relates to mortality. We examined single and combined associations between BMI, WC, waist-hip ratio (WHR) and all-cause, cardiovascular disease (CVD) and cancer mortality. METHODS: We used Cox proportional hazard regression models to estimate relative risks of all-cause, CVD and cancer mortality in 8061 adults (aged 18-74 years) in the Canadian Heart Health Follow-Up Study (1986-2004). Models controlled for age, sex, exam year, smoking, alcohol use and education. RESULTS: There were 887 deaths over a mean 13 (SD 3.1) years follow-up. Increased risk of death from all-causes, CVD and cancer were associated with elevated BMI, WC and WHR (P<0.05). Risk of death was consistently higher from elevated WC versus BMI or WHR. Ascending tertiles of each anthropometric measure predicted increased CVD mortality risk. In contrast, all-cause mortality risk was only predicted by ascending WC and WHR tertiles and cancer mortality risk by ascending WC tertiles. Higher risk of all-cause death was associated with WC in overweight and obese adults and with WHR in obese adults. Compared with non-obese adults with a low WC, adults with high WC had higher all-cause mortality risk regardless of BMI status. CONCLUSION: [corrected] BMI and WC predicted higher all-cause and cause-specific mortality, and WC predicted the highest risk for death overall and among overweight and obese adults. Elevated WC has clinical significance in predicting mortality risk beyond BMI.

Home versus center based physical activity programs in older adults.

BACKGROUND: Physical inactivity is a leading cause of preventable death and morbidity in developed countries. In addition physical activity can potentially be an effective treatment for various medical conditions (e.g. cardiovascular disease, osteoarthritis). Many types of physical activity programs exist ranging from simple home exercise programs to intense highly supervised hospital (center) based programs. OBJECTIVES: To assess the effectiveness of 'home based' versus 'center based' physical activity programs on the health of older adults. SEARCH STRATEGY: The reviewers searched the Cochrane Central Register of Controlled Trials (CENTRAL) (1991-present), MEDLINE (1966-Sept 2002), EMBASE (1988 to Sept 2002), CINAHL (1982-Sept 2002), Health Star (1975-Sept 2002), Dissertation Abstracts (1980 to Sept 2002), Sport Discus (1975-Sept 2002) and Science Citation Index (1975-Sept 2002), reference lists of relevant articles and contacted principal authors where possible. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials of different physical activity interventions in older adults (50 years or older) comparing a 'home based' to a 'center based' exercise program. Study participants had to have either a recognised cardiovascular risk factor, or existing cardiovascular disease, or chronic obstructive airways disease (COPD) or osteoarthritis. Cardiac and post-operative programs within one year of the event were excluded. DATA COLLECTION AND ANALYSIS: Three reviewers selected and appraised the identified studies independently. Data from studies that then met the inclusion/exclusion criteria were extracted by two additional reviewers. MAIN RESULTS: Six trials including 224 participants who received a 'home based' exercise program and 148 who received a 'center based' exercise program were included in this review. Five studies were of medium quality and one poor. A meta-analysis was not undertaken given the heterogeneity of these studies. CARDIOVASCULAR. The largest trial (accounting for approximately 60% of the participants) looked at sedentary older adults. Three trials looked at patients with peripheral vascular disease (intermittent claudication). In patients with peripheral vascular disease center based programs were superior to home at improving distance walked and time to claudication pain at up to 6 months. However the risk of a training effect may be high. There are no longer term studies in this population. Notably home based programs appeared to have a significantly higher adherence rate than center based programs. However this was based primarily on the one study (with the highest quality rating of the studies found) of sedentary older adults. This showed an adherence rate of 68% in the home based program at two year follow-up compared with a 36% adherence in the center based group. There was essentially no difference in terms of treadmill performance or cardiovascular risk factors between groups. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). Two trials looked at older adults with COPD. In patients with COPD the evidence is conflicting. One study showed similar changes in various physiological measures at 3 months that persisted in the home based group up to 18 months but not in the center based group. The other study showed significantly better improvements in physiological measures in the center based group after 8 weeks but again the possibility of a training effect is high. OSTEOARTHRITIS. No studies were found. None of the studies dealt with measures of cost, or health service utilization. AUTHORS' CONCLUSIONS: In the short-term, center based programs are superior to home based programs in patients with PVD. There is a high possibility of a training effect however as the center based groups were trained primarily on treadmills (and the home based were not) and the outcome measures were treadmill based. There is conflicting evidence which is better in patients with COPD. Home based programs appear to be superior to center based programs in terms of the adherence to exercise (especially in the long-term).

Trends in overweight and obesity among adults in Canada (1970-1992): evidence from national surveys using measured height and weight.

PURPOSE: To examine secular trends in obesity and overweight among Canadian adults between 1970 and 1992. The impact of education level and smoking on weight trends is explored. DATA: Adults aged 20-69 participating in three national health surveys which obtained measured height and weight: the Nutrition Canada Survey conducted between 1970 and 1972 (analysis sample n=5963); the Canada Health Survey of 1978-1979 (analysis sample n=3622); and the Canadian Heart Health Surveys conducted between 1986 and 1992 (analysis sample n=17 699). METHODS: Comparison of percentage overweight (age-standardized body mass index (BMI) 25.0-29.9) and obese (age-standardized BMI > or = 30.0) by sex, education level and smoking status across the three surveys. RESULTS: Among men, the proportion overweight and obese increased steadily from 1970-1972 to 1986-1992. Among women, there was a substantial increase in the proportion overweight and obese between 1970-1972 and 1978-1979, then an increase in proportion obese, but not overweight, between 1978-1979 and 1986-1992. Although the prevalence of obesity increased in all education levels, the sub-groups with the greatest relative increase are men in the primary education category, and women in the secondary and post-secondary between 1970-1972 and 1986-1992. An increase in the prevalence of obesity was greatest among current smokers and, to a lesser extent, among former smokers. CONCLUSION: While excess weight has become an increasing public health problem among Canadian adults, the rate of increase in prevalence of obesity since 1970 varied with sex, education level and smoking status. There is a need for new data on measured heights and weights of Canadian adults and children and youth to update trends.

The Saskatchewan dissemination story.

The Saskatchewan Heart Health Program (SHHP) Dissemination Phase "Building Health Promotion Capacity" is a five-year program funded by Health Canada, Saskatchewan Health and the Heart and Stroke Foundation of Saskatchewan. This phase began in July 1998 and builds on two previous SHHP phases: the provincial heart health survey (Saskatchewan Health, 1990), and the community demonstration projects (SHHP, 1998a, b, c, d). The evolution of the SHHP has occurred in a dynamic provincial context. Saskatchewan is a Canadian prairie province of one million people with most living in the southern and central parts of the province. The population is ageing and urbanizing, and the economy is shifting away from agricultural production toward a diversified service sector. In 1993, health reform created 30 Districts in southern and central Saskatchewan; the formation of three northern Districts followed five years later. All but two Districts are rural-based. Population served ranges from 2,261 to 237,274; total area ranges from 4,019 to 133,900 square kilometers.

Regional and rural-urban differences in obesity in Canada. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To describe regional and rural-urban differences in weight and weight loss patterns in Canadian adults. DESIGN: Population-based, cross-sectional surveys. SETTING: Nine Canadian provinces (excluding Nova Scotia) from 1986 to 1992. PARTICIPANTS: A probability sample of 27,120 men and women aged 18 to 74 years was selected using the health insurance registration files in each province. Anthropometry was performed on 18,043 participants (67%). OUTCOME MEASURES: Region of Canada (Atlantic, central, western); rural or urban residence (rural if participant resided in a community whose population was < 10,000, urban if population > or = 10,000); body mass index (BMI, kg/m2); percentage of participants trying to lose weight; reasons for trying to lose weight; level of leisure-time physical activity. RESULTS: Overall, mean BMI values in rural men (26.1 kg/m2) and women (25.3 kg/m2) were not significantly different from urban counterparts (25.7 kg/m2 and 24.8 kg/m2, respectively). Similarly, obesity (BMI > or = 27 kg/m2) was as prevalent in rural men (37%) and women (30%) as in urban participants (34% and 28%, respectively). However, a difference was observed in western Canada where 41% of rural and 34% of urban men were obese (odds ratio [OR], adjusted for age and education = 1.29; 95% confidence interval [CI] 1.06, 1.57), as were 35% of rural and 25% of urban women (OR, adjusted for age and education = 1.47; 95% CI 1.17, 1.84). Among men in western Canada, the rural-urban differences were greatest in the 25-64 year age group, whereas in women the differences were present at all ages. Overall, in Canada, urban men (26%) are more likely than rural men (23%) to be trying to lose weight; the reverse was true for women (39% and 42%, respectively). CONCLUSION: Considerable regional and rural-urban differences are seen in the patterns of weight and weight loss in Canada. A fuller understanding of the underlying behavioural determinants of these differences is needed. On the basis of such an understanding, effective programs to promote healthy weights for individuals and communities in these areas might be developed.

Obesity in Canada: a descriptive analysis. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To describe the distribution of body fat, prevalence of obesity, and knowledge of cardiovascular disease in Canadian adults. DESIGN: Population-based, cross-sectional surveys. SETTING: Ten Canadian provinces between 1986 and 1992. PARTICIPANTS: A probability sample of 29,855 men and women aged 18 to 74 years was selected using health insurance registration files in each province. Anthropometry was performed on 19,841 (66%) of these adults. OUTCOME MEASURES: Body mass index (BMI); waist circumference; ratio of waist to hip circumference; knowledge of causes of heart disease. RESULTS: The overall prevalence of obesity (BMI > or = 27 kg/m2) increased with age and was greater in men (35%) than in women (27%). Abdominal obesity was also higher in men and increased with both age and BMI. Canadians with lower levels of education had a higher prevalence of obesity, which appeared at a young age. Canadians in Atlantic Canada mentioned lack of exercise, poor diet and smoking as causes of heart disease less frequently than those living in central or western Canada. CONCLUSIONS: Obesity continues to be common among Canadian adults. Policy and programs to promote healthy body weights must be intensified and directed at specific sociodemographic groups.

Risk factor correlates of body mass index. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To examine the association of obesity, as reflected by body mass index, with other cardiovascular risk factors specifically blood pressure, smoking, physical inactivity, plasma lipid levels and diabetes mellitus. DESIGN: Population-based, cross-sectional surveys. SETTING: Ten Canadian provinces between 1986 and 1992. PARTICIPANTS: A probability sample of 29,855 men and women aged 18 to 74 years was selected from the health insurance registration files of each province and invited to participate. Anthropometry was performed on 19,841 (66%) of these adults. OUTCOME MEASURES: Body mass index (BMI, kg/m2), systolic and diastolic blood pressure, smoking status, level of leisure-time physical activity, self-reported diabetes, levels of plasma total cholesterol, high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL) and triglycerides (TRIG). RESULTS: The prevalence of high blood pressure increased with increasing BMI. The gradient of increase was steepest for younger (18-34 years) men and women compared with older (55-74 years) groups. The prevalence of physical inactivity in women tended to increase with increasing BMI except in the lowest BMI category. The J-shaped relationship, although weaker, was also seen in men. The prevalence of self-reported diabetes mellitus was greater with higher BMI categories at all ages and for both sexes except for the youngest group of men. The prevalence of dyslipidemia was related to BMI, as LDL and TRIG levels were higher and HDL levels lower in those with higher BMI. BMI was strongly related to blood pressure, diabetes mellitus and lipid abnormalities. CONCLUSION: These data suggest a central role for obesity in cardiovascular risk and the potential importance of intervention strategies aimed at reducing population obesity in the management of other cardiovascular risk factors.

A comparative analysis of weight to height and waist to hip circumference indices as indicators of the presence of cardiovascular disease risk factors. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To determine the mathematic formula for weight, height and waist and hip circumference that is most closely correlated to cardiovascular disease risk factors. DESIGN: Population-based, cross-sectional surveys. SETTING: Five Canadian provinces, between 1990 and 1992. PARTICIPANTS: A probability sample of 16,007 men and women aged 18 to 74 years was selected using health insurance registration files in each province. Anthropometry was performed on 10,054 (63%) of these adults. OUTCOME MEASURES: The power of height in the body mass index (BMI, kg/m2) and of hip circumference in the ratio of waist to hip circumference (WC/HC) was varied from 0 to 3. Simple linear regression analysis for each age-sex group was used to examine the relation of each index to systolic and diastolic blood pressure (SBP and DBP), levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL), triglycerides (TRIG) and the ratio of TC to HDL. Values for the coefficient of determination (r2) were used to compare the fits of the models. RESULTS: The r2 values were generally low (< 0.27), but were greatest in the younger age groups (18-24 and 35-54 years) and in women. Waist circumference alone (WC/HC0) showed the best fit with SBP and DBP, whereas WC/HC0.5 was most closely related to HDL, TC/HDL and TRIG. None of the indices was closely associated with TC or LDL. Whatever the power of height used, the weight-height ratios showed weaker associations with the risk factors than the waist-hip ratios. CONCLUSIONS: WC and BMI correlate most closely with blood pressure and plasma lipid and may be the best simple anthropometric indices to include in the routine clinical examination of adults.

The association of cardiovascular disease risk factors with abdominal obesity in Canada. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To assess the degree of association of abdominal obesity with blood pressure and plasma lipid levels and to determine which anthropometric measures of obesity are most closely associated with these cardiovascular risk factors. DESIGN: Population-based, cross-sectional surveys. SETTING: Five Canadian provinces (Alberta, Manitoba, Ontario, Quebec and Saskatchewan) between 1989 and 1992. PARTICIPANTS: A probability sample of 16,007 men and women aged 18 to 74 was selected using health insurance registration files in each province and invited to participate. A complete set of measurements was available for 8974 (56%) adults. OUTCOME MEASURES: Initially, simple correlation analyses by age and sex were performed between the anthropometric variables-body mass index, waist circumference (WC), hip circumference (HC), ratio of waist to hip circumference (WHR)- and cardiovascular disease risk variables-systolic blood pressure (SBP), diastolic blood pressure (DBP), levels of total cholesterol (TC), low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides (TRIG) and the TC/HDL ratio. Canonical correlation analyses were performed to determine the multivariate associations between the anthropometric and risk variables. RESULTS: The simple correlations between anthropometric variables and cardiovascular disease risk variables were highest for SBP; moderate for DBP, HDL, TRIG and TC/HDL; and lowest for LDL and TC. Of the anthropometric variables, WC demonstrated the greatest correlations with the risk variables. The first canonical correlations were significant (p < 0.0001) in men (0.58) and women (0.61) of all ages. Of the anthropometric variables, WC consistently demonstrated the highest loading values in the first canonical variable in men (0.56) and women (0.59). Of the risk variables in both sexes, the loadings of TRIG were generally the largest, those of HDL, SBP, DBP intermediate and those of LDL the smallest. In men, the strength of these associations generally decreased with age, whereas in women they peaked in the 35-54 year age group. CONCLUSION: Considerable association was seen between measures of abdominal obesity and blood pressure and plasma lipid levels. WC is the measure of abdominal obesity most highly correlated with these cardiovascular disease risk factors.

Correlation between cardiovascular disease risk factors and simple anthropometric measures. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To assess simple anthropometric measures as indicators of the concurrent presence of high blood pressure, dyslipidemia and diabetes mellitus in adults. DESIGN: Population-based, cross-sectional surveys. SETTING: Five Canadian provinces between 1990 and 1992. PARTICIPANTS: A probability sample of 16,007 men and women aged 18 to 74 years was selected using health insurance registration files in each province. This study is based on the 9826 adults (61%) for whom anthropometric measurements were obtained. OUTCOME MEASURES: Step-wise multiple logistic regression analysis was used to model the association between demographic, anthropometric and risk variables and the presence of high systolic and diastolic (DBP) blood pressure, elevated levels of total (TC), high-density lipoprotein (HDL) and low-density lipoprotein cholesterol, TC/HDL ratio, triglyceride levels (TRIG) and self-reported diabetes mellitus. RESULTS: Age group and sex are strongly associated with all three conditions. Sedentary lifestyle is significantly associated with high DBP, depressed HDL and elevated TC/HDL and TRIG. Anthropometric measures are moderately associated with all conditions. The measures of body fat (body mass index) as well as abdominal fat distribution (waist circumference and ratio of waist to hip circumference) play an approximately equal role. CONCLUSION: Patients' age, sex, level of physical activity, body fat and abdominal fat distribution can be used as indicators of the probability of high blood pressure, dyslipidemia and diabetes mellitus.

Heart health in rural Saskatchewan.

In Saskatchewan, as in the rest of Canada, cardiovascular disease (CVD) is the leading cause of death and hospitalization. Indeed, the rate of decline in mortality has been slower in Saskatchewan than in most other provinces. So when the federal-provincial Canadian Heart Health Initiative was established in 1986, the province set up the Saskatchewan Heart Health Program both to form part of the national initiative and to take advantage of the opportunities implicit in it.

Sociodemographic variation in the prevalence of cardiovascular disease.

OBJECTIVE: To estimate the prevalence and social correlates of cardiovascular disease. DESIGN: Population-based cross-sectional survey. Survey data were obtained through a standardized home interview and a clinic visit by trained nurses. The question sequence of the London School of Hygiene (the Rose Questionnaire) was used to identify the presence of definite angina, possible infarction, definite infarction, intermittent claudication and stroke. SETTING: Eight urban communities and rural areas in Saskatchewan in 1990. PARTICIPANTS: A probability sample of 2167 noninstitutionalized men and women aged 18 to 74 years who participated in the Saskatchewan Heart Health Survey. MAIN OUTCOME MEASURES: Prevalence of cardiovascular diseases. RESULTS: Among men, the prevalence of definite angina increased gradually with age from 1.7% (95% CI 0.6% to 2.7%) in the 18 to 34 year group, 3.8% (1.3% to 6.0%) in the 35 to 54 year group to 4.8% (2.8% to 8.3%) in the 55 to 74 year group, while the prevalence among women ranged from 2.5% (1.2 to 3.7%), 4.0% (1.6% to 6.5%) to 7.1% (5.1% to 11.6%) in these same age groups. The prevalence of possible angina, definite infarction, possible infarction and intermittent claudication increased with age as well, being higher in men than in women. Generally, the conditions were more prevalent among those with less education, lower income and those who were unemployed. CONCLUSIONS: These findings indicate that there is sociodemographic inequality in the prevalence of these manifestations of cardiovascular disease, and there is a need for in-depth qualitative research into causal factors in this relationship and for targeted programs of health promotion.

Selective screening for dyslipidemia in a Canadian population.

The study assesses the clinical features of individuals that best enable an effective selective screening of the adult population for dyslipidemia. The results of the population-based 1990 Saskatchewan Heart Health Survey were examined. Dyslipidemia was defined as a total cholesterol (TC) to high-density lipoprotein cholesterol (HDL) ratio of > or = 5. In total, 805 men and 782 women, 18-74 years of age, had their plasma cholesterol measured. Using TC screening of the entire population as recommended by the Canadian Consensus Conference on Cholesterol would correctly identify 79% of those with dyslipidemia (sensitivity) and 67% of those with a normal profile (specificity). However, if one performs lipoprotein analysis on only those with a high waist-to-hip circumference ratio (WHR), 44% of the population would need to be screened to correctly identify 71% of those with dyslipidemia (sensitivity) and 66% of those with a normal profile (specificity). A high WHR is an especially strong predictor of dyslipidemia in young adults. In conclusion, a high WHR may provide an effective means of selective screening of the adult population for dyslipidemia.

Age-related association between body mass index and blood pressure: the Humboldt Study.

OBJECTIVE: To investigate how age modifies the relation between body mass and blood pressure. DESIGN: Community based cross-sectional study. SUBJECTS: 2865 residents aged 6 to 74 years (85.6% of the target population) in the town of Humboldt, Saskatchewan, Canada. MEASUREMENTS: Body mass index [weight (kg)/height (meters)2], and diastolic and systolic blood pressures. RESULTS: Among the subjects, 99.6% were of Caucasian origin. With both sexes, there was a stronger relation between body mass index and diastolic blood pressure in younger age groups than older age groups. In males, the increase in mean blood pressure for a 1-unit increase in body mass index (kg/m2) was 0.72, 0.72, 0.41 and 0.47 mm Hg in the 6-14, 15-34, 35-54 and 55-74 year age groups respectively. In females, the correspondent increase was 0.95, 0.57, 0.46 and 0.43 mm Hg. In females, age also modified the relation between body mass index and the prevalence of high blood pressure. The odds ratios for high blood pressure for a 1-unit increase in body mass index in females was 1.33, 1.21, 1.12 and 1.10 in the 6-14, 15-34, 35-54 and 55-74 year age groups. CONCLUSION: Age significantly modifies the relations of body mass index with mean diastolic blood pressure in both sexes, and with the prevalence of high blood pressure in females. The relations are stronger in children and young adults than in older persons.

Risk factor awareness: a randomized telephone survey of public knowledge.

Health educators are often faced with the dilemma of developing materials or programs that begin at a level appropriate to the needs of individuals or the population as a whole. In 1992, a randomized telephone survey of the public's knowledge of risk factors relating to stroke was conducted in Saskatoon. The risk factors most frequently identified were poor diet (40%), hypertension (36%) and stress (36%). Respondents with a family history of stroke were significantly more likely to identify hypertension as a risk factor than those without such a history and significantly less likely to identify stress as a risk factor. In all, 24% reported a family history of acute myocardial infarction, and 28% reported a family history of stroke. Eighty percent were willing to learn more about the risk factors, and 88% were willing to make the appropriate lifestyle changes to reduce their risk of an event. Assessment of public knowledge can help in planning initiatives directed at prevention, early identification and appropriate referral.

Surveillance for stroke in Canada.

The goal of surveillance is to identify patterns of disease occurrence, detect disease outbreaks, develop clues about possible risk factors, find persons that need further investigation, and anticipate health service needs. Two sources of data are available for the purposes of surveillance: primary data, such as those arising from health surveys or local population-based registries; and secondary data, arising from large administrative databases. The effectiveness of any program to monitor the health of a community can be judged by the application of three "r's": right (accuracy), reasonable (cost) and rapid (speed). Programs using primary sources of data satisfy only one of the three "r's," that of accuracy. Programs using secondary sources sacrifice accuracy for speed and cost. The challenge for Canada in setting up surveillance for stroke is that there is a relatively small population unevenly distributed over a very large geographical area. To date, surveillance in Canada has consisted of a combination of individually initiated research projects and government sponsored programs. The main focus has been to tackle the issue of the accuracy of the large databases by validating the discharge codes listed in the provincial hospital discharge databases. Three provinces have carried out independent validation studies yielding remarkably similar results, and this lends confidence that hospital discharge databases will provide a means of carrying out surveillance for at least this one aspect of stroke. It is likely that any program for stroke surveillance in Canada will be multifaceted, involving the use of large computerized databases supplemented by hospital-based registries set up in a few highly motivated local centres. Stroke surveillance will best be accomplished by a joint effort between government and researchers to ensure that the end product is of high quality and will meet the needs of improving the health of Canadians.

Using pyridoxine to treat carpal tunnel syndrome. Randomized control trial.

In this study, we examined prospectively the effect of pyridoxine on idiopathic carpal tunnel syndrome. Thirty-two patients with the disease were randomized to receive treatment or placebo. No differences in outcome were found in electrophysiologic signs, clinical signs, or significant symptoms. Our findings do not support the use of pyridoxine for treating carpal tunnel syndrome.