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Temporal trends in cardiovascular disease risk factors among white, South Asian, Chinese and black groups in Ontario, Canada, 2001 to 2012: a population-based study Maria Chiu,1 Laura C Maclagan,1 Jack V Tu,2,3,4 Baiju R Shah1,5
To cite: Chiu M, Maclagan LC, Tu JV, et al. Temporal trends in cardiovascular disease risk factors among white, South Asian, Chinese and black groups in Ontario, Canada, 2001 to 2012: a population-based study. BMJ Open 2015;5:e007232. doi:10.1136/bmjopen-2014007232 ▸ Prepublication history and additional material is available. To view please visit the journal (http://dx.doi.org/ 10.1136/bmjopen-2014007232). Received 17 November 2014 Revised 22 May 2015 Accepted 13 June 2015
ABSTRACT Objectives: To determine ethnic-specific temporal trends in cardiovascular risk factors in Ontario between 2001 and 2012. Design: A population-based repeated cross-sectional study. Setting: Ontario, Canada. Participants: 219 276 participants of the Canadian Community Health Survey (205 326 white, 5620 South Asian, 4368 Chinese and 3962 black) during the period 2001 to 2012. Main outcome measures: Age-standardised ethnicsex-specific prevalence of cardiovascular risk factors for three time periods: 2001–2004, 2005–2008 and 2009–2012 among Canada’s four major ethnic groups: white, South Asian, Chinese and black. Results: During the study period, the prevalence of diabetes increased 2.3-fold ( p=0.0001) among South Asian males and 1.9-fold ( p=0.02) among black females. The prevalence of obesity (body mass index ≥30 kg/m2) increased over time across all ethnic groups, with the largest relative increases observed among males of Chinese (2.1-fold increase, p=0.04) and black (1.7-fold increase, p=0.06) descent. The prevalence of hypertension increased the most among black females. Smoking prevalence decreased by more than 20% among South Asian, Chinese and white females. Overall, South Asian males and black males and females showed the greatest declines in cardiovascular health over the study period. Conclusions: We observed important ethnic differences in the temporal trends in cardiovascular risk factor profiles in Ontario. Awareness of the direction and magnitude of these risk factor trends may be useful in informing targeted strategies for preventing cardiovascular diseases in multiethnic populations.
For numbered affiliations see end of article. Correspondence to Dr Maria Chiu;
[email protected]
INTRODUCTION Cardiovascular disease risk factors, such as tobacco use, high-blood pressure, obesity and
Strengths and limitations of this study ▪ This is the first study to examine temporal trends in the prevalence of cardiovascular risk factors across Canada’s four major ethnic groups. ▪ Comprehensive cardiovascular risk factor data were available for a large representative population-based sample over a 12-year period. ▪ Limitations of the study are the use of selfreported data and the lack of information on lipids and details on diet.
physical inactivity are among the leading causes of morbidity and mortality worldwide.1 Globally, the prevalence of most cardiovascular disease risk factors has been increasing in developing and developed regions of the world due in part to increasing urbanisation and the adoption of sedentary lifestyles.2 Large increases in the global prevalence of diabetes and mean body mass index have been found in two recent meta-analyses of epidemiological data.3 4 Earlier studies have shown that the prevalence of key cardiovascular risk factors, such as obesity, hypertension and diabetes are on the rise in Canada,5 while smoking rates have declined.6 Similar trends have been documented in population-based studies in the USA7 and the UK.8 Migration between countries is becoming increasingly common, with Europe, Asia and North America receiving the highest numbers of international migrants in 2013.9 As international migration continues to increase, so too do projections for ethnic diversity in many countries such as Canada, the US and the UK.10 Canada is one of the most ethnically diverse nations in the world, with over 6 million (20.6%) foreign-born individuals living in Canada in 2011, the
Chiu M, et al. BMJ Open 2015;5:e007232. doi:10.1136/bmjopen-2014-007232
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Open Access highest proportion among the G8 countries.11 Moreover, the three most populous ethnic minority populations in Canada, the Chinese, South Asian and black ethnic groups, also represent approximately 60% of the world’s population. Despite Canada’s ethnic diversity, there is little known about whether the prevalence of cardiovascular risk factors is changing differently over time across different ethnic groups. An understanding of ethnic disparities in temporal trends is important for predicting future burden of cardiovascular disease in Canada and other multiethnic nations; however, population-based risk factor data on individual ethnic groups especially over time have been limited, thus precluding previous analysis of trends by ethnicity. Ethnic differences in the overall prevalence of all major cardiovascular risk factors are well documented in the literature; including previous work published by our group, which found significant differences in the prevalence of cardiovascular risk factors across white, South Asian, Chinese and black ethnic groups in Ontario.12 Evidence suggests that South Asians generally have a higher prevalence of diabetes and hypertension12–14 and white populations have a higher prevalence of smoking and obesity15 16 compared to other ethnic groups. Ethnic differences in the temporal trends in the prevalence of cardiovascular risk factors have been reported among South Asian and Chinese individuals living in the UK8 17 and among white and black groups living in the USA.18 19 What is not known is whether cardiovascular risk factor prevalence is changing differently over time across the major ethnic groups living in Canada. The objective of this study was to examine temporal trends in the prevalence of key cardiovascular risk factors from 2001 to 2012 across Ontario’s four major ethnic groups: white, South Asian, Chinese and black.
METHODS Data sources and study population The study population included Ontario residents who responded to Statistics Canada’s Canadian Community Health Survey (CCHS) cycles 1.1 (2001), 2.1 (2003), 3.1 (2005), 2007, 2008, 2009, 2010, 2011, 2012. Data from multiple cross-sectional CCHS cycles with independent samples were combined so that temporal trends could be examined across three time periods: 2001–2004, 2005–2008 and 2009–2012 with adequate sample sizes in each of the four ethnic groups. The CCHS used a consistent multistage stratified cluster sampling strategy to collect self-reported data on sociodemographic characteristics and health-related information from a representative sample of persons aged 12 years or older living in private dwellings. The individual response rates for the surveys ranged from 75.1% to 94.4%. The surveys were conducted by highly-skilled interviewers in over 25 languages. Further details about the CCHS methodology are described elsewhere.20 2
In this study, we analysed Ontario residents who identified their racial-cultural group as white, Chinese, South Asian (ie, those of Indian, Pakistani, Bangladeshi or Sri Lankan origin) or black (ie, those of African or Caribbean origin). Study variables Sociodemographic characteristics included age, sex, marital status, highest level of education attained in the household and by the individual, household income in Canadian dollars, immigrant status and urban or rural dwelling. We analysed a total of eight cardiovascular risk factors, including four major risk factors (ie, diabetes, obesity (BMI≥30 kg/m2), current smoking and hypertension); and four other risk factors (ie, inadequate leisure physical activity, inadequate fruit and vegetable consumption, psychosocial stress and non-regular alcohol consumption). Inadequate leisure physical activity was defined as participating in ≤15 min of daily leisure physical activity (eg, walking for exercise, jogging, swimming, bicycling, etc); inadequate fruit and vegetable intake was defined as eating fruits or vegetables fewer than three times a day;21 psychosocial stress was defined as an individual feeling ‘extremely’ or ‘quite a bit’ versus ‘not at all’, ‘not very’ or ‘a bit’ stressed on most days. Non-regular alcohol consumption was defined as consuming fewer than three drinks per week.22 Diabetes and hypertension were self-reported physician-diagnosed and included both treated and untreated conditions. We also assessed trends in the mean BMI (kg/m2) and the prevalence of overweight/obesity (BMI ≥25 kg/m2) by ethnic group. Statistical analyses We calculated the age-standardised and sex-standardised prevalence of sociodemographic characteristics and the age-standardised sex-specific prevalence of cardiovascular risk factors for each of the three time periods across the four ethnic groups. We used direct standardisation with 5-year age bands and the 2001 Ontario census as the standard population. All analyses were weighted by Statistics Canada’s sample weights to account for the complex survey sampling design and to improve generalisability of the estimates. Per cent changes in the prevalence of risk factors between the 2009–2012 and 2001– 2004 periods were calculated; 95% CIs and p values were estimated using bootstrap methods.23 24 All tests were two-sided and p
