Baseline findings from the circumpolar Inuit Health in Transition cohort study negate the belief that the Inuit are spared from CVD, and confirm that smoking, obesity and elevated BP are major, modifiable cardiovascular risk factors encountered in this population. However, the Nunavik Inuit still enjoy an exceptional plasma lipid profile (high HDL-C and low TAG), which influences their CVD risk.
Our study reveals that the prevalence of some CVDs among the Nunavik Inuit reached values recorded among other Canadians. For instance, in 2003, the prevalence of self-reported angina in Canadian men and women was 1.8% and 1.9%, respectively (42
). In our investigation, we obtained similar results – age-standardized rates were 2.3% and 1.9%, respectively, among men and women.
We also compared our results with hospitalization separation rates after IHD and CD recorded in 1999 (43
) in Canada (IHD 607.4/100,000 person-years, CD 221.9/100,000 person-years) and Quebec (IHD 646.4/100,000 person-years, CD 243.5/100,000 person-years). In Nunavik, the crude rate in 2004 was 883.3/100,000 person-years and 543.5/100,000 person-years for IHD and CD, respectively. The rates from Nunavik were higher, specifically for CD.
Even if previous comparisons are based on age-standardized rates or crude rates, it is noteworthy that they are not exactly comparable because the data came from different sources, such as self-reported questionnaires versus medical files in our study. These comparisons are, nevertheless, interesting to obtain an overview of CVD morbidity and an estimate of the phenomenon’s magnitude.
Moreover, the elevated prevalence of CVD found in our investigation corroborates a recent report (44
) from the Institut national de santé publique du Québec, which showed that the age-adjusted mortality rate from all CVDs was the highest (450/100,000 person-years) in Nunavik compared with other regions of the province. The mortality rate from all CVDs in the province of Quebec was reported to be 218/100,000 person-years (44
Based on the mortality data, IHD and CD have been represented as having different burdens in the Inuit population – the former being lower than in the non-native population, and the latter being higher (20
). With a similar prevalence (less than 3%), our data did not reveal any difference between both diseases. Furthermore, other comparisons of the crude rates of these diseases to non-native populations have challenged previous results. However, an ongoing study evaluating the accuracy of death certificates will adequately answer this question.
Another significant finding was that the Inuit population from Nunavik cumulated several major cardiovascular risk factors such as smoking, obesity and hypertension. Smoking is a common habit among the Inuit; more than 84% of individuals reported smoking, and this rate was alarmingly high among young people. Since the 1992 health survey, an increase of approximately 10% has been recorded, whereas a decline of tobacco consumption was recently noted in the rest of Canada (37
The prevalence of obesity and overweight in the Inuit also warrants urgent action – 28% of Inuit participants were obese. The proportion was higher than that recorded among the general Canadian population (23%) (48
). However, as clearly evoked recently by Young et al (49
), the impact of obesity needs to be explored in detail because associated metabolic parameters common among obese Caucasians are less disrupted among the Inuit. The low prevalence rate of the MetS found in the present study again supports previous observations. Nevertheless, the complex anthropometry of Arctic populations requires further exploration.
Interestingly, whereas no sex difference was seen in obesity levels measured by BMI, a clear distinction appeared when abdominal obesity was considered. Women had higher rates of abdominal obesity. This last point draws attention to Inuit women who cumulate most major cardiovascular determinants such as smoking, elevated BP and sedentary lifestyles. Poor health status among women has already been observed among Alaskan Inuit women (51
Hypertension, the leading disease reported in the medical files of participants (12%), was lower (27%) than in the adult Canadian population 35 to 64 years of age (52
) but similar to that in the adult population (aged 20 years and older) of the province of Quebec (13.8%) (37
). In parallel, among people without CVD, the prevalence of elevated BP also appeared to be increased. Altogether, HBP reached values of those recently recorded in this country (52
). Moreover, the prevalence of HBP among older Inuit (55 years of age or older) was higher in Nunavik than in Alaska (63% versus 34%) (51
). Notwithstanding previous rates in people without CVD, BP values always seemed to be lower than those reported among residents from the southern part of Quebec (25
In 1992, the results showed that the blood lipid profile of the Inuit from Nunavik was healthier than that of Quebecers (33
). However, with the expected increase in consumption of westernized foods, researchers have predicted a deterioration of their blood lipid profile. Twelve years later, mean HDL-C and TAG are still in the normal range. Furthermore, we observed a surprising increase of HDL-C concentration across age categories, particularly among women. This latest result is of great interest because 72% of Inuit women are abdominally obese, and Ghandehari et al (53
) reported a negative association between HDL-C and WC among American adults.
This encouraging blood profile, corroborated by the generally low Framingham risk score, suggests that the Inuit population has a weak propensity for developing CAD. Nevertheless, our recent finding of high trans-fat dietary intake (54
) and its deleterious interaction with blood lipid profile (55
) could raise the risk of CAD among the Inuit Nunavik population.
The prevalence of diabetes was estimated to be 4.7%. This rate is comparable with values in the rest of Canada (5.5%) (39
) and those recorded recently among Quebecers (3.7%) (37
). In the present analysis, diabetes was considered to be a risk factor for CVD. Its prevalence fell to less than 1% after excluding individuals with declared CVD. Thus, diabetes does not represent an important concern for the Inuit population without CVD.
Previous interpretations should be considered in light of the fact that the circulatory system diseases presented here are extracted from the medical files, and the diagnoses were not validated by another physician. This might trigger less precision in the description of the disease. Consequently, because of the small Nunavik population size, these impressions might have introduced an information bias that may have had a significant impact on the prevalence recorded. This limitation will be corrected in the follow-up of our cohort by rigorous evaluation of cardiovascular events. Moreover, comparisons with Canadian Community Health Survey data on risk factors are limited due to the nature of data that are self-reported by the patient in the survey and reported from medical files or directly measured in our study. Nevertheless, these comparisons are essential to complete the general portrait of CVD burden among the Inuit population. Finally, sedentary lifestyle was self-reported. Such an assessment of the absence of physical activity reduces the potential bias introduced by social desirability.
Our study aimed to provide an overview of prevalence rates of CVD and potentially associated risk factors among the Nunavik Inuit. Our main findings draw attention to risk factors among women who cumulate many CVD determinants and indicate the precarious health status of women from this Canadian Arctic population. The age/sex relationship with other factors such as obesity (general and visceral) and lipid profile is interesting, and a key to the evolution (increase or decrease) of CVD burden in this population. Despite the cross-sectional nature of the present analysis, sex-adapted public intervention is crucial to reduce their risk.