Heart risks vary by ethnicity: Ont. study

Chinese, South Asians, whites and blacks living in Ontario show striking differences in their cardiovascular risk factors and disease, a large new study shows.

In the study, published in Monday's issue of the Canadian Medical Association Journal, researchers compared cardiovascular risk factors such as smoking, obesity, diabetes, hypertension, and physical activity across 163,797 people representing all four ethnic groups from 1996 to 2007.

"Despite universal access to health care, ethnic groups living in Ontario differed markedly in their cardiovascular risk profiles," wrote study authors Maria Chiu and Dr. Jack Tu, of Toronto's Institute for Clinical Evaluative Sciences, and their co-authors.

"Awareness of these differences will become increasingly important as ethnic minority groups come to represent a larger proportion of the Canadian population."

The researchers found that the Chinese population had the lowest overall prevalence of heart disease (3.2 per cent) and stroke (0.6 per cent), while South Asians of Indian, Pakistani, Bangladeshi or Sri Lankan origin had the highest prevalence (5.2 per cent and 1.7 per cent).

Common factors

Smoking and obesity were more common in the white population, while the South Asian and black populations of African or Caribbean descent  had the highest levels of diabetes and hypertension, the researchers found.

Other findings included:

• Rates of diabetes among the South Asian (8.1 per cent) and black (8.5 per cent) groups were twice as high as among white (4.2 per cent) and Chinese (4.3 per cent).
• Obesity was five times more prevalent among white (14.8 per cent) and blacks (14.1 per cent) than Chinese (2.5 per cent). The prevalence of obesity among South Asians was 8.1 per cent.
• Black women were more likely to be physically inactive and obese than the overall population.
• South Asian and Chinese women were also less likely to participate in daily physical activity than the overall population.

The evidence suggests that ethnic groups do not have same needs in terms of health care, Chiu said.

Earlier screening

"We should target our prevention and screening strategies accordingly so they can reduce the burden of cardiovascular disease," she said in an interview.

There is no reason the results would not apply to the Canadian population as a whole, Chiu said.

Smoking rates in Chinese (8.7 per cent) and South Asian (8.6 per cent residents in Ontario were significantly lower than in China (28.9 per cent) and India (15.6 per cent),

The researchers conclude that there may be a need to develop ethnically tailored strategies for preventing cardiovascular risk factors in Canada.

"The good news for this story is that these are modifiable risk factors," Chiu said. "We can certainly take measures and make lifestyle changes that could prevent a large proportion of cardiovascular diseases."

Dr. Chi-Ming Chow of St . Michael's Hospital in Toronto agreed with the study's authors about the implications for screening and prevention.  

"It's really a wake-up call for us to actually pay attention and ask about their ethnic background, their lifestyles and then be vigilant, especially among certain populations, especially among the black population and also South Asian population," Chow said. 

"So as opposed to standard recommending recommending risk-factor screening once a year — using the standards that we use in the white population — I think we should actually start screening the patients from South Asia as well as patients from the black population … earlier, to start looking for blood pressure problems, cholesterol problems, and diabetes, as well is paying a lot of attention about their weight and to whether or not they live a healthy lifestyle or not."

If these problems are recognized and mitigated earlier, starting in the late 30s, then doctors and patients can try to delay the onset of heart disease and stroke, he said.

Paradoxically, despite their poor risk profile, black people in the study had a relatively low prevalence of heart disease.

This may have something to do with other risk factors such as lower levels of stress and likelihood of smoking, Chiu said. Other studies have also found mortality differences, where blacks don't live as long after they are diagnosed with heart disease.  

Chow advised regular checkups, including blood pressure, cholesterol and blood sugar monitoring.

The study was funded by the Heart and Stroke Foundation of Ontario.