We found that visible minorities differed in terms of the prevalence of cardiovascular risk factors relative to white respondents. Within the combined visible minority group, the prevalence of these risk factors varied greatly across ethnicities. The prevalences of obesity and smoking were lower in the visible minorities than in the white population, but physical inactivity was more prevalent among the visible minorities. The South Asian, Filipino or South East Asian, and black ethnic groups had significantly higher prevalences of diabetes and hypertension than the white respondents, and the Korean, Japanese and Latin populations were as physically inactive as the white population.
Our findings of high prevalence of cardiovascular risk factors among black people in Canada support findings from the United States. In 2003–2004, black people in the United States had a high prevalence of hypertension, 39.1% of the population.29
Recent data from the Canadian province with the largest population (i.e., Ontario), based on physical measurements, demonstrated a 31.5% prevalence of hypertension in the black population,30
much higher than our finding of 14.2%. This difference indicates that the self-reported survey data used in our study were missing cases of undiagnosed hypertension. Another difference between research from the United States and our study is the prevalence of overweight in the black populations (69.6% in one US study31
v. 43.5% with BMI of 25 or higher in our Canadian study). There are historical differences between the United States and Canada in terms of the pathways of immigration for black people. Many US black people have ancestral roots in slavery, have less education and have social disadvantages that may lead to health inequalities. Although Canadian black people initially emigrated from the United States, many later immigrants have come from the Caribbean and Africa, reflecting Canadian immigration policies, which have tended to increase the number of educated immigrants.32,33
Nevertheless, inequalities in the prevalence of cardiovascular risk factors exist in Canada. The higher prevalences of hypertension and overweight among black respondents relative to other visible minorities may be attributable to different cultural norms regarding lifestyle and health behaviours.34
In our study, people from visible minorities, particularly South Asian respondents, reported high levels of physical inactivity, consistent with findings from similar studies in the United Kingdom and the United States.7,35,36
More interesting was the finding that Chinese respondents with chronic disease were as physically inactive as white respondents with chronic disease (adjusted OR 1.01, 95% CI 0.73–1.40), but Chinese respondents without chronic disease were more likely to be physically inactive than white respondents with chronic disease (adjusted OR 1.68, 95% CI 1.49–1.90). The low prevalence of physical inactivity among Chinese respondents with chronic disease has been reported from the United States37
and from China.38
Two possible reasons are that elderly Chinese people may value health maintenance and disease prevention through physical activity more and may have more time to do exercise than do their younger counterparts. In addition, beliefs about physical activity may play an important role. Kandula and Lauderdale,39
who analyzed data from the California Health Survey, found that physical activity among Asian Americans increased significantly with length of stay in the United States and with ability to speak English. Their findings suggest that acculturation promotes physical activity.
Compared with white respondents, levels of overweight and obesity were lower among Chinese, Japanese or Korean, South Asian, and Filipino or South East Asian respondents. At least one previous study has shown that South Asian people have a greater percentage of body fat than white people, even at low BMI, which results in an increased risk of diabetes, cardiovascular disease and other metabolic disorders.40
There is a need for a lower BMI cutoff to identify overweight Asian people and prevent premature cardiovascular disease in this population.41
Furthermore, with increased duration of residence in developed countries, immigrants tend to become overweight or obese as they become sedentary and adapt to high-calorie diets, which indicates an erosion of the initial healthy immigrant effect.42-45
Thus, although the proportion of people of visible minorities who are obese is currently relatively low, it is likely to increase over time, and the initiation of effective preventive measures is therefore warranted.
Our study had some limitations. First, the reliability and validity of the survey were not assessed. Because the survey responses were self-reported, the level of recall bias and the underreporting of risk factors across ethnic populations were unknown. Physical measurement of hypertension and BMI would provide more accurate data than self-reported values. Leung and colleagues46
conducted a cross-sectional telephone survey of Chinese and white residents in Calgary, Canada, to assess health status in terms of a 5-point Likert-type scale, a health index scale (0–100) and number of chronic conditions. They reported that health status across these 3 measures was inconsistent among the Chinese respondents. In addition, the Chinese respondents were more likely than the white respondents to report values close to the midpoint of the 2 rating scales. However, it is unknown, from that study or others, whether different ethnic groups report health data differently. Second, although the CCHS was conducted in several languages, people with language barriers and sicker people were less likely to be surveyed. Third, our exclusion of individuals with missing values for the variables might have resulted in slight selection bias. However, we excluded only a small number of respondents with missing values, which likely had minimal impact on our large sample. Fourth, we estimated obesity using BMI but lacked important information about waist and hip circumference. Fifth, caution should be exercised in generalizing our findings to ethnic populations outside Canada, because ethnic groups vary across geographic regions for certain risk factors. These differences could result in underestimation of the prevalence of cardiovascular risk factors.
In conclusion, the prevalence of cardiovascular risk factors varied across ethnic groups in Canada. Further research is needed to understand the protective and restrictive factors underlying these variations in prevalence within visible minorities, the Aboriginal population and the white population. The unique risk factor profiles of each ethnic group need to be considered during health promotion activities. Promoting physical activity to specific visible minorities, such as Chinese and South Asian people, should be prioritized in population health programs. In addition, aggressive programs for the prevention, early detection and control of diabetes and hypertension may need to target South Asian, Filipino and black people.