Written by: Marlene Busko

OTTAWA, ON — Within a year, obesity will overtake smoking as the number-one modifiable cardiovascular disease (CVD) risk factor in Canada, researchers predict[1]. Moreover, the prevalence of diabetes is expected to increase over the next seven years, according to this study, which was published online May 20, 2014 in CMAJ Open.

The researchers developed a model that simulates changes in five CVD risk factors—diabetes, hypertension (systolic blood pressure > 140 mm Hg), high cholesterol (total cholesterol >6.22 mmol/L), current smoking, and obesity (body mass index [BMI] >30)—in the Canadian population from 2001 to 2021.

The good news, however, is that “we expect CVD incidence—adjusted for Canada’s larger, aging population—to decrease through to 2021,” the researchers write. The model projects a decrease in smoking, uncontrolled hypertension, and dyslipidemia, which each confer a two- to threefold increased risk of CVD.

“For the first time we have credible evidence that the rate of heart disease is set to decline in Canada as a result of progress in controlling high blood pressure and cholesterol levels and helping people to stop smoking,” lead author Dr Douglas G Manuel (Ottawa Hospital Research Institute, ON) said in a statement.

However, even though the rates of obesity and diabetes are expected to rise in the Canadian population, for individuals, smoking remains a worse health hazard, he stressed.

The researchers admit that even though they validated and adjusted the model using Canadian survey data from 2003 to 2009, the “actual future prevalence of risk factors beyond the validation period (ie, after 2009) will undoubtedly vary from our projections.

“The prevalence of risk factors could be lower than our projections if . . . physical and social conditions improve or if efforts to prevent hypertension and dyslipidemia are strengthened. Conversely, Canada’s physical and social environment may become more conducive to an increase in obesity.”

To examine how the incidence of CVD might change in the coming years, the researchers created a simulated Canadian population of 11 million men and 11.5 million women by using the 2001 Canadian Community Health Survey of 105 908 individuals age 20 and older. Then they projected how CVD risk factors of each individual would change over the next 20 years.

At baseline, 28.4% of men and 23% of women smoked and 15.9% of men and 14.4% of women were obese. About 16% of the population had uncontrolled hypertension; about 14% had high cholesterol; and about 5% had diabetes. The model predicted that in 2021, the prevalence of smoking would drop to 17.7%, and uncontrolled hypertension would decrease to 10.8%.

Despite inherent limitations, “projecting CVD risks using a microsimulation approach can inform decision making with the goal of continued reductions in CVD risk and incidence,” the researchers write.

What About Other CVD Risk Factors?

In an invited commentary in CMAJ [2], Dr Garry Egger (Southern Cross University, Lismore, Australia) and Dr John Dixon (Baker IDI Heart and Diabetes Institute, Melbourne, Australia) write that “Manuel and colleagues’ analysis describes the relative importance of some risk factors, but it seems that we have yet to fully elucidate all factors that contribute to what has recently been labeled a lifestyle-related disease.”

They point out that excessive alcohol consumption, a sedentary lifestyle, low intake of fruits and vegetables, and a high intake of saturated fat have been implicated in CVD. Social, political, environmental, and economic factors can affect whether people make healthy lifestyle choices.

“Reducing traditional risk factors for cardiovascular disease will have an important and relevant role in addressing the growing burden of chronic disease in our communities in the coming years, as shown by Manuel and colleagues,” they agree. “However, this role is likely to be limited if we do not address the underlying drivers of risks and anticipate and manage changing determinants,” they add.

References

1. Manuel D, Tuna M, Henessy D, et al. Projections of preventable risks for cardiovascular disease in Canada to 2021: A microsimulation modelling approach. CMAJ Open 2014; DOI:10.9778/cmajo.20120015. Article

2. Egger G, Dixon J. The risk of addressing only risks. CMAJ 2014; DOI:10.1503 /cmaj.140138. Editorial

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