The authors have declared that no competing interests exist.
Analyzed the data: DW. Wrote the paper: ASG SK. Contributed to study conception and design: ASG SK JK TT EJC LP JM DAH. Contributed to acquisition of data (MNO Citizenship Registry): YA SJR. Interpreted data: ASG SK DW. Contributed to revisions of manuscript: ASG SK JK DW TT EJC LP JM YA SJR DAH.
Chronic respiratory diseases cause a significant health and economic burden around the world. In Canada, Aboriginal populations are at increased risk of asthma and chronic obstructive pulmonary disease (COPD). There is little known, however, about these diseases in the Canadian Métis population, who have mixed Aboriginal and European ancestry. A population-based study was conducted to quantify asthma and COPD prevalence and health services use in the Métis population of Ontario, Canada’s largest province.
The Métis Nation of Ontario Citizenship Registry was linked to provincial health administrative databases to measure and compare burden of asthma and COPD between the Métis and non-Métis populations of Ontario between 2009 and 2012. Asthma and COPD prevalence, health services use (general physician and specialist visits, emergency department visits, hospitalizations), and mortality were measured.
Prevalences of asthma and COPD were 30% and 70% higher, respectively, in the Métis compared to the general Ontario population (p<0.001). General physician and specialist visits were significantly lower in Métis with asthma, while general physician visits for COPD were significantly higher. Emergency department visits and hospitalizations were generally higher for Métis compared to non-Métis with either disease. All-cause mortality in Métis with COPD was 1.3 times higher compared to non-Métis with COPD (p = 0.01).
There is a high burden of asthma and COPD in Ontario Métis, with significant prevalence and acute health services use related to these diseases. Lower rates of physician visits suggest barriers in access to primary care services.
Chronic respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD), are a leading cause of morbidity and mortality worldwide
Aboriginal peoples have been found to be at increased risk of chronic respiratory diseases in many countries, including Canada
The Métis are one of the founding Aboriginal Peoples of Canada, descended from unions between First Nations women and European men. In the 2011 Canadian National Household Survey, 451,795 people self-identified as Métis, accounting for 32% of the overall Aboriginal population in Canada
Studies based on the 2001 and 2006 cycles of the APS suggest that asthma is more prevalent among the Métis than other adults in Canada
To address this research gap, we used health administrative data to conduct a population-based study to quantify asthma and COPD burden in the Ontario Métis population, in terms of prevalence, health services use, and outcomes. To contextualize the results, we compared asthma and COPD in the Métis to the rest of the Ontario population.
The research described here was commissioned by the Métis Nation of Ontario (MNO) and conducted at the Institute for Clinical Evaluative Sciences (ICES). This study was approved by the Research Ethics Board of Sunnybrook Health Sciences Centre, Toronto, Ontario and was conducted under guidelines for research with Aboriginal communities that have been developed by Canada’s three principal research agencies
We conducted a population-based study from April 1, 2009 to March 31, 2012 by linking the Métis Nation of Ontario Citizenship Registry to health administrative data from Ontario
Our source population was identified in the Métis Nation of Ontario (MNO) Citizenship Registry, which contains information on all Métis citizens who are able to supply genealogical documentation and historical proof of Métis ancestry. Probabilistic linkage of this database to the health administrative data on an individual level was performed with 97% success. Residents of Ontario are insured under the Ontario Health Insurance Plan (OHIP). Personal health information is captured in provincial health administrative databases which can be linked together, using unique health insurance numbers, to give complete health services use profiles of all those living in the province. In this study, six health administrative databases were used. The Registered Persons Database is a central registry of all insured persons in Ontario which also records death information, where appropriate. The Ontario Health Insurance Program claims database contains all fee-for-service billing claims from physicians for consultations, visits and procedures. The National Ambulatory Care Reporting System contains diagnostic information related to all emergency department visits. The Discharge Abstracts Database contains information about all hospitalizations including diagnoses and procedures performed.
Finally, the Ontario Asthma Surveillance Information System and the Ontario Chronic Obstructive Pulmonary Disease Databases are validated databases of all people in Ontario with asthma and COPD
Disease | Health AdministrativeData Case Definition | International Classificationof Diseases-9 andOntario Health InsuranceProgram Codes forhospitalizations priorto 2002 andambulatory care visits | International Classificationof Diseases-10 Codesfor hospitalizationsafter 2002 | Sensitivity | Specificity |
Asthma |
1 asthma hospitalizationand/or 2 asthma ambulatorycare visits within 2 years | 493 | J45, J46 | 84% | 76% |
Chronicobstructivepulmonarydisease |
1 COPD hospitalizationand/or 1 COPD ambulatory inan adult aged 35 and older | 491, 492, 496 | J41, J43, J44 | 85% | 78% |
Gershon AS, Wang C, Vasilevska-Ristovska J, Guan J, Cicutto L, et al. (2009) Identifying patients with physician diagnosed asthma in health administrative databases. Can Respir J 16∶183–188.
Gershon AS, Wang C, Guan J, Vasilevska-Ristovska J, Cicutto L, et al. (2009) Identifying individuals with physician diagnosed COPD in health administrative databases. COPD 6∶388–394.
All individuals recorded in the Métis registry and successfully linked with health administrative data were included and hereafter are referred to as “the Métis”. All other Ontario residents were considered the general population. Both populations were further limited to people who were alive, living in Ontario and eligible for health insurance as of April 1, 2009. When considering asthma outcomes, we excluded individuals under the age of 20 as the Métis Registry underrepresents this age group. When considering COPD outcomes, we excluded individuals under the age of 35 as COPD is rare in younger individuals.
People with prevalent asthma and/or COPD were identified as of April 1, 2009 using the validated asthma and COPD databases described above. They were then followed for three years to determine if they died. Those who were still alive had their health services utilization measured during the follow-up period. We looked at disease-specific and all-cause ambulatory care visits (primary care practitioner and specialist visits), emergency department visits, and hospitalizations.
To account for differences between the Métis and the rest of the Ontario population, demographics such as age, sex, and geographic variables were obtained using the Registered Persons Database. Geographic variables, generated using the Statistics Canada Postal Code Conversion File
Characteristic | Métis | Ontario |
12,350 | 9,833,152 | |
45.9 (15.1) | 47.8 (17.3) | |
20–39 | 36.4 | 35.4 |
40–59 | 44.3 | 39.5 |
60 and older | 19.3 | 25.1 |
Male | 53.3 | 48.4 |
Female | 46.7 | 51.6 |
Southern Ontario | 53.3 | 93.6 |
Northern Ontario | 46.7 | 6.4 |
1 (poorest/lowest) | 22.1 | 19.3 |
2 | 20.9 | 19.9 |
3 | 20.3 | 19.9 |
4 | 18.8 | 20.5 |
5 (richest/highest) | 17.3 | 20.1 |
Urban | 69.3 | 88.3 |
Rural | 30.7 | 11.7 |
Métis and general population cohorts were limited to persons aged 20+, alive, living in Ontario and eligible for health insurance.
Neighbourhood income was calculated by Statistics Canada. Canadian neighbourhoods are classified into one of five approximately equal-sized groups (quintiles), ranked from poorest (quintile1) to wealthiest (quintile 5).
Based on the Statistics Canada definition of rurality, where Census Metropolitan Areas that have a population less than 10,000 are considered to be rural.
Counts and proportions were generated for all covariables in the Métis and Ontario populations. Asthma and COPD prevalence were generated overall and by age group, sex and urban/rural status for both the Métis and the general Ontario population. Chi-square tests were used to test for differences, with p-values less than 0.05 considered significant. Rates of ambulatory care visits, emergency department visits, hospitalizations and mortality were calculated per 1000 person-years. Due to the differences in demographic structure and geographic location of the two study populations, all rates were direct-standardized for age, sex, and urban/rural status to the 2006 Ontario Census population. 95% confidence intervals were calculated using the gamma method
A total of 12,350 Métis were included in this study. Compared to the general population cohort (N = 9,833,152), the Métis were slightly younger and a higher percentage were male and resided in Northern, rural, and lower-income areas of the province (
In the Métis, the overall crude prevalence of asthma was 15% (
ASTHMA | CHRONIC OBSTRUCTIVEPULMONARY DISEASE | |||||
Métis | Ontario | P-value | Métis | Ontario | P-value | |
1797 | 1,170,139 | 1309 | 696,242 | |||
14.6 (13.9–15.2) | 11.9 (11.9–11.9) | <0.001 | 16.7 (15.8–17.6) | 11.0 (10.9–11.0) | <0.001 | |
15.6 (14.8–16.4) | 11.8 (11.8–11.8) | <0.001 | 17.3 (16.1–18.5) | 10.2 (10.1–10.2) | <0.001 | |
20–29 | 23.7 | 24.1 | N/A | N/A | ||
30–39 | 20.1 | 16.5 | N/A | N/A | ||
40–49 | 21.3 | 18.6 | 15.8 | 12.1 | ||
50–59 | 17.5 | 16.0 | 29.6 | 22.8 | ||
60–69 | 11.7 | 11.5 | 30.1 | 24.2 | ||
70–79 | 4.3 | 8.0 | 18.3 | 22.7 | ||
80 and older | 1.5 | 5.2 | 6.2 | 18.2 | ||
Male | 42.3 | 41.0 | 53.0 | 48.9 | ||
Female | 57.7 | 59.0 | 47.0 | 51.1 | ||
Urban | 74.2 | 89.0 | 66.2 | 83.6 | ||
Rural | 25.8 | 11.0 | 33.8 | 16.4 |
N/A: Not applicable.
Crude rate per 100 people (95% confidence interval).
Direct-standardized rate by age, sex and urban/rural status to the 2006 Ontario Census population.
Crude COPD prevalence was 17% in the Métis and was highest in the 50 to 69 year age group, males, and urban dwellers. The standardized COPD prevalence was 1.7 times higher in the Métis than in the general Ontario population (17% vs. 10%, p<0.001).
Between 2009 and 2012, more than 90% of both Métis and non-Métis people in the province with asthma or COPD visited a primary care practitioner (
ASTHMA | CHRONIC OBSTRUCTIVEPULMONARY DISEASE | |||||
Métis | Ontario | P-value | Métis | Ontario | P-value | |
N (%) with visit | 613 (91.4) | 1,058,482 (92.5) | 1160 (94.5) | 603,657 (94.7) | ||
Standardized rate | 4984.6(4896.2–5074.1) | 5374.5(5371.3–5377.6) | <0.001 | 6171.5(6042.3–6302.7) | 6031.3(6025.9–6036.7) | 0.005 |
N (%) with visit | 319 (18.1) | 237,280 (20.7) | 243 (19.8) | 105,014 (16.5) | ||
Standardized rate | 178.2(162.7–194.7) | 224.8(224.2–225.5) | <0.001 | 201.8(181.2–224.1) | 175.0(174.2–175.8) | 0.002 |
N (%) with visit | 1143 (64.8) | 753,899 (65.9) | 923 (75.2) | 495,581 (77.7) | ||
Standardized rate | 2334.2(2273.6–2395.9) | 2433.4(2431.2–2435.5) | <0.001 | 2831.8(2746.2–2919.5) | 2931.5(2927.9–2935.1) | 0.004 |
N (%) with visit | 60 (3.4) | 65,880 (5.8) | 37 (3.0) | 40,491 (6.4) | ||
Standardized rate | 32.4 (26.4–29.4) | 69.3(68.9–69.7) | <0.001 | 20.7 (15.2–27.5) | 64.6(64.1–65.1) | <0.001 |
All rates per 1000 person-years, direct-standardized to the 2006 Ontario Census population by age, sex and urban/rural status (with 95% confidence intervals).
During the study period, about 60% of Métis with either asthma or COPD visited an emergency department, although only between 5 and 6% had an asthma- or COPD-specific visit (
ASTHMA | CHRONIC OBSTRUCTIVE PULMONARY DISEASE | |||||
Métis | Ontario | P-value | Métis | Ontario | P-value | |
N (%) with visit | 1031 (58.5) | 504,900 (44.1) | 731 (59.6) | 319,222 (50.1) | ||
Standardized rate | 761.7 (729.0–795.8) | 563.9 (562.9–565.0) | <0.001 | 910.7 (861.3–962.2) | 674.3 (672.5–676.2) | <0.001 |
N (%) with visit | 85 (4.8) | 33,768 (3.0) | 75 (6.1) | 32,266 (5.1) | ||
Standardized rate | 26.3 (21.2–32.3) | 21.5 (21.3–21.7) | 0.05 | 26.7 (20.4–34.3) | 32.2 (31.9–32.5) | 0.13 |
N (%) with visit | 280 (15.9) | 152,486 (13.3) | 293 (23.9) | 136,821 (21.5) | ||
Standardized rate | 118.9 (104.5–134.7) | 93.1 (92.6–93.5) | <0.001 | 176.3 (155.9–198.5) | 132.7 (132.0–133.4) | <0.001 |
N (%) with visit | 20 (1.1) | 9903 (0.9) | 0.31 | 66 (5.4) | 32,823 (5.2) | |
Standardized rate | 5.8 (3.2–9.8) | 4.7 (4.6–4.8) | 32.9 (25.1–42.3) | 25.0 (24.7–25.3)* | 0.01 |
All rates per 1000 person-years, direct-standardized to the 2006 Ontario Census population by age, sex and urban/rural status (with 95% confidence intervals).
Standardized all-cause mortality was 1.3 times higher for Métis compared to other Ontarians with COPD (39.0 vs. 29.0 deaths per 1000 people, p = 0.01). Standardized all-cause mortality was similar between Métis and non-Métis with asthma (68.0 vs. 65.0 deaths per 1000 people, p = 0.67).
We conducted a population-based cohort study of the Ontario population that confirmed that Métis people living in Ontario had a higher prevalence of physician-diagnosed asthma and COPD than the rest of the Ontario population. We also found generally lower rates of primary care practitioner and specialist visits for these diseases among the Métis, suggesting disparity in access to and/or utilization of ambulatory health care for this group of Ontarians. These results could be contributing the higher rates of emergency department visits and hospitalizations also observed for asthma and COPD among Métis populations.
To the best of our knowledge, this is the first large-scale, population study to quantify asthma and COPD in the Ontario Métis population in terms of health services use. Its results point to a disturbing gap in respiratory health between the Métis and non-Métis that requires further study.
Our findings are consistent with the self-reported asthma prevalence rates of the Métis who participated in the 2006 Aboriginal People’s Survey
A number of factors are likely contributing to the higher prevalence of asthma and COPD observed among the Ontario Métis. The prevalence of smoking, a known risk factor for COPD and a trigger for asthma, is 33% for the Métis population nationally, nearly twice that of the Canadian general population
We also found disparities in health services use, with generally lower rates of ambulatory care visits observed among the Métis, along with higher rates of acute care services. These results are similar to those found in an Alberta study, where specialist visit rates for asthma and COPD were lower in Aboriginal peoples than the general population, despite significantly higher disease rates
The strengths of our study were its population base, comprehensiveness and ability to capture and compare rates in the Métis to a general non-Métis population. It also has limitations which merit emphasis. First, while use of health administrative data has been widely advocated for use in chronic disease surveillance as an efficient, available and relatively inexpensive way to obtain population-based measures of disease burden
A second important limitation is that the Citizenship Registry of the MNO is voluntary and does not include all Métis in the province; as such, it may not be representative of the entire Métis population. However, it is the largest, most complete registry of Métis in Ontario and provides the best representation of Métis respiratory health currently available. Our results are also likely a conservative estimate of the differences between Métis and non- Métis, since any non-registered Métis people would have been included in the general population of this study, thereby minimizing any true differences between Métis and non-Métis populations. Furthermore, Métis citizens, by virtue of the fact that they had the capacity, energy and motivation to undertake the comprehensive process required to register and be recognized as citizens, are likely healthier than non-registered Métis residents, making our results even more likely to be conservative estimates of disease in this population.
Finally, the Métis registry has few people under the age of 18 and so we were unable to look at the burden of asthma in children. As asthma tends to have a higher burden among the younger age groups, this may be another reason why our results underestimate the total burden of asthma in the Métis. The MNO is currently working towards increasing the registration of children in their Citizenship Registry, and this additional data will be valuable in examining this issue.
In summary, we conducted a population-based cohort study and found that citizens of the Métis Nation of Ontario had higher rates of asthma and COPD and related acute health services use than the general Ontario population. These analyses suggest deficiencies in primary health care access for these diseases for the Métis that make this population more reliant on emergency services to address their health care needs. Future research should focus on confirming these findings in the entire Métis population, examining respiratory conditions in younger populations, identifying specific factors that are contributing to higher rates of asthma and COPD among the Métis compared to the rest of the Ontario population, and determining strategies to minimize the disease burden for this at-risk population.