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Asthma and COPD Among Aboriginals in Alberta, Canada^*

^* From the Department of Medicine, Pulmonary Division, (Drs. Sin and Man, and Ms. Wells), and Alberta Health and Wellness (Mr. Svenson), University of Alberta, Edmonton, Alberta, Canada.

Correspondence to: Don D. Sin, MD, MPH, 2E4.29 Walter C. Mackenzie Center, University of Alberta, Edmonton, AB., Canada. T6G 2B7; e-mail: don.sin{at}ualberta.ca

	Abstract

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Background: Aboriginals in Canada bear a disproportionately higher burden of some chronic illnesses than nonaboriginals. Although there is a greater prevalence of smoking, poor housing, and overcrowding in aboriginal than nonaboriginal communities, the rates of office and emergency visits for asthma and COPD among aboriginals are not well known.

Study objective: To determine whether aboriginals require higher rates of asthma and COPD emergency and office visits than nonaboriginals.

Setting: Population-based cohort of people residing in Alberta, Canada (population 2.8 million) between April 1, 1996, and March 31, 1997.

Design: Retrospective cohort study.

Results: We observed that aboriginals were 2.1 times (95% confidence interval [CI], 2.0 to 2.2) and 1.6 times (95% CI, 1.6 to 1.6) more likely to have an emergency and office visit for asthma or COPD, respectively, when compared to age-matched and sex-matched nonaboriginals. However, they were 55% (95% CI, 52 to 58%) less likely to see a specialist and 66% (95% CI, 63 to 70%) less likely to undergo spirometry than nonaboriginals.

Conclusions: These findings indicate that aboriginals bear a disproportionately higher burden of asthma and COPD than nonaboriginals. However, lower use of spirometry and specialist services suggests that there might be access barriers to quality health care for aboriginals in Canada.

Key Words: aboriginals • asthma • COPD • emergency

	Introduction

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The aboriginal peoples of Canada bear a disproportionately larger burden of disease and die a decade earlier than the average population.^{1 2} The infant mortality rate for aboriginals is double the national average, and aboriginal children have hospitalization rates that are five times higher than similar nonaboriginal children.³ Almost one third of aboriginal people 15 years old have a chronic health condition.¹ They experience higher rates of infections, diabetes, substance abuse, renal diseases, mental illnesses, and suicide.¹

In the past, chronic respiratory conditions such as asthma and COPD have been thought to be uncommon in the aboriginal community; however, more-recent findings suggest otherwise.⁴ According to a report from the Royal Commission on Aboriginal Peoples of Canada, > 19% of aboriginals 15 years old reported having chronic health problems of asthma, bronchitis, and emphysema.⁵ This rate is much higher than those that have been reported previously, indicating that asthma and COPD may be increasing at a faster rate in the aboriginal community compared to the rest of the population.⁶ However, the impact of asthma and COPD on health-service utilization among aboriginals remains unknown. Using population-based data, we sought: (1) to determine the rates of emergency and office visits for asthma and COPD among aboriginals, (2) to compare these rates with those of the nonaboriginal population, and (3) to determine the rates of referral to specialist services and spirometry to understand whether aboriginal patients with asthma or COPD face potential access barriers to quality care.

	Materials and Methods

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Sources of Data
Treaty Status: Alberta is the fourth-largest province in Canada, with an estimated population of 2.8 million people. Similar to other Canadian provinces, the Provincial Government of Alberta provides universal health-care coverage for all its residents through a publicly administered single-payer insurance plan. The Alberta Health Care Insurance Plan (AHCIP) maintains an updated electronic file that contains pertinent demographic information on all Alberta residents, including their age, sex, and area of residence. This database also contains information on "treaty" status of residents. In Canada, treaty status is given to those individuals of aboriginal heritage who have been registered as Indians with the federal government.⁶ In Alberta, this group comprises mostly of North American Indians (ie, "First Nations" members). "Treaty Indians" make up approximately 85 to 90% of the total aboriginal population. Treaty Indians receive free health care (physician, hospital, and emergency visits) and free prescribed medications. We use the term aboriginals synonymously with the term treaty Indians in this study.

Physician Encounters for Asthma or COPD: All physician encounters are electronically registered by the provincial government through the physicians’ claims database. This database is used for surveillance purposes and to reimburse physicians for all services rendered by them. Each claim in this database contains the most responsible diagnosis, the diagnostic fee code, and the specialty qualifications of the physician as well as the location where the service was rendered. Diagnoses are encoded using the International Classification of Diseases (ICD-9-CM) codes. We used ICD-9-CM code 493 for asthma, and codes 490, 491, 492, and 496 for COPD. These ICD-9-CM codes have been used previously to identify those with asthma and COPD.^{7 8 9 10} Different fee codes exist for different types of physician encounters, which allowed us to separate out emergency visits from office visits.

Specialist Visit and Use of Spirometry: Specialists were defined as those physicians not actively practicing primary care medicine, and they included general internists, respirologists, allergists, and pediatricians. We obtained "specialty" information for the physicians from the physicians’ claims database. In addition, since performance and interpretation of spirometric tests are reimbursed through the AHCIP, we were able to capture the use of spirometry for patients in the cohort using the same database.

Data Linkages
For this study, we evaluated the relationship between aboriginal status and use of health services for asthma and COPD from April 1, 1996, to March 31, 1997. To do this, we linked the AHCIP registry and physicians’ claims databases together using a common unique health-care number, which was encrypted to maintain patient confidentiality.

Statistical Analysis
Baseline characteristics were compared using a ² test for dichotomous variables and t tests for continuous variables. We used a Poisson regression analysis to determine the association between aboriginal status and the risk of emergency and office visits for asthma and COPD.¹¹ In this analysis, aboriginal status was the independent variable, while office or emergency visits for asthma and COPD was the dependent variable. To the baseline model that included only aboriginal status and risk for office or emergency visits, we added one by one patients’ age, sex, and area of residence. Person-years were log-transformed and included in the model as an offset.¹² The general Poisson (loglinear) regression used in this study was m_i = N_ie^ßX_i, where i = aboriginal or nonaboriginal status (ie, race); m_i = expected count for observed count n_i; n_i = observed count in each "race" group; N = the population at risk for each "race" group (x_i = individual covariates [eg, age, sex, metropolitan variables] and their effect on "race" variable).¹² The area of residence was divided into metropolitan (population of 500,000) and nonmetropolitan (population < 500,000) centers. We did this because differential health-service utilization might be present between those living in metropolitan and nonmetropolitan areas.¹³ For instance, specialists tend to cluster in urban areas, which may limit access to specialists for patients living in remote rural areas¹⁴ ; and since more aboriginals resided in nonmetropolitan areas than nonaboriginals,⁵ area of residence could be a potential confounding variable.

Because asthma and COPD may be difficult to separate clinically,¹⁵ we analyzed asthma and COPD data combined as well as separately. All p values were two sided; p values < 0.05 were considered statistically significant. Relative risks (RRs) and 95% confidence intervals (CIs) were constructed using standard methods. All analyses were conducted with SAS software (version 8.1; SAS Institute; Cary, NC) and SPSS software (version 9.0; SPSS; Chicago, IL).

	Results

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During the study period, there were 2,855,715 residents in Alberta. Of these, 100,580 residents (3.5%) were aboriginals. Aboriginals were younger than nonaboriginals. The mean (SD) age of aboriginals was 23.9 (19.1) years, and the mean age of nonaboriginals was 34.6 (27.1) years (p < 0.001). There were no gender differences in the two communities, as female subjects made up 50.1% of the total for each population. Aboriginals were much less likely to reside in metropolitan areas. Only 29.9% of aboriginals (n = 30,079) were living in metropolitan centers, whereas 59.5% of nonaboriginals (n = 1,638,910) resided in metropolitan centers (p < 0.001). During the study period, there were 31,763 emergency visits and 290,846 office visits for asthma and COPD. Of the emergency visits, 2,426 visits (7.6%) occurred among aboriginals and 29,337 visits (92.4%) occurred among nonaboriginals. Aboriginals had 15,712 office visits (5.4%), and nonaboriginals had 275,134 office visits (94.6%). Among aboriginals, 13.3% of all asthma-related and COPD-related physician encounters were emergency visits; in contrast, only 9.6% of all asthma-related and COPD-related physician encounters were emergency visits for nonaboriginals (p < 0.001)

Within all age groups, aboriginals had higher rates of emergency visits (Fig 1 ) and office visits (Fig 2 ) for asthma and COPD. Adjustments for age and sex made little difference to the overall results (Table 1 ). Even in metropolitan centers, aboriginals had a higher rate of emergency and office visits for asthma and COPD (Table 2 ). We also analyzed rates of emergency visits for asthma and COPD separately. We found that aboriginal status increased the risks of emergency and office visits for both asthma and COPD (Table 3 ).

View larger version (30K): [in this window] [in a new window] [Download PPT slide]   Figure 1.. An age-standardized comparison of emergency visits for asthma or COPD between aboriginals and nonaboriginals in Alberta.

View larger version (32K): [in this window] [in a new window] [Download PPT slide]   Figure 2.. An age-standardized comparison of office visits for asthma or COPD between aboriginals and nonaboriginals in Alberta.

Of those who had at least one office visit for asthma or COPD, 921.6 per 10,000 aboriginals saw a specialist (defined as internists, respirologists, allergists, or pediatricians), while 1,431.5 per 10,000 nonaboriginals saw a specialist during the same period of time (adjusted RR, 0.45; 95% CI, 0.42 to 0.48). In metropolitan centers, the rate was 1,703.2 per 10,000 for aboriginals and 1,856.4 for nonaboriginals (RR, 0.65; 95% CI, 0.58 to 0.71). When asthma and COPD were analyzed separately, in both conditions, aboriginals were less likely to see a specialist and to receive spirometric testing than nonaboriginals (Table 3) .

We performed a subgroup analysis comparing the rates of emergency visits for asthma and COPD in aboriginals to the very poor (nonaboriginals) in Alberta, whose annual taxable income was < $7,560. This low-income group also received health care and prescribed medications free of charge. In this comparison, aboriginals had higher rates of asthma (RR, 1.23; 95% CI, 1.16 to 1.31) and COPD emergency visits (RR, 1.32; 95% CI, 1.23 to 1.41) than low-income earners of nonaboriginal descent. Aboriginals were less likely to have had spirometry measurements (RR, 0.29; 95% CI, 0.26 to 0.33) and less likely to have seen a specialist than the very poor nonaboriginals (RR, 0.27; 95% CI, 0.22 to 0.32). These comparisons suggest that low income alone cannot fully account for the differential use of health services for asthma and COPD in the community.

To determine whether diagnostic misclassification could have led to an overestimation in the rates of asthma and COPD among aboriginals, we performed an additional analysis comparing rates of emergency visits for acute respiratory illnesses (ICD-9CM codes 460 to 466), which in clinical practice may be mistaken for asthma or COPD. In this comparison, we found that aboriginals had a higher rate of emergency visits for acute respiratory tract infections than nonaboriginals (RR, 2.17; 95% CI, 2.13 to 2.22), suggesting that aboriginals are at a higher risk for having acute as well as chronic respiratory illnesses develop. Diagnostic misclassification, therefore, would have led to an underestimation in the rates of asthma and COPD among aboriginals.

	Discussion

TOP Abstract Introduction Materials and Methods Results Discussion References

 
The main finding of this study was that aboriginal residents had higher rates of physician visits for asthma and COPD than nonaboriginals in Alberta. They were 2.1 times more likely to use emergency services and 1.6 times more likely to have had office visits for asthma and COPD when compared to nonaboriginals, suggesting a disproportionately higher rates of these chronic airway conditions in the aboriginal community than the rest of the population. These observations are similar to those reported in the literature. Hemmelgarn and Ernst¹⁶ found that 6% of school-aged Inuit children had exercise-induced bronchospasm and 8% had airflow obstruction. Senthilselvan and Habbick⁶ showed that the rates of hospitalization for asthma were up to three times higher in aboriginal than in nonaboriginal children. Interestingly, in the 1970s, the rates of asthma hospitalization in the aboriginal population were similar to those in the nonaboriginal communities, indicating a disproportionate rise in asthma-related hospitalization among aboriginals over the past 2 decades. Liu et al¹⁷ reported that aboriginal children in the first year of life have rates of hospitalization for asthma and bronchiolitis that were two to three times higher than those of nonaboriginal children. As with the study by Senthilselvan and Habbick,⁶ they observed a striking twofold increase in the rate of hospitalization for asthma and bronchiolitis in aboriginal children since the mid 1980s, whereas only a 50% increase was observed among nonaboriginal children during the same period of time. Our study demonstrates a similar twofold increase in the rate of emergency visits for asthma and COPD among aboriginals compared to nonaboriginals.

Our study also provides new insights concerning the epidemiology of chronic airway conditions in the aboriginal community. We showed that aboriginals had increased rates of asthma-related and COPD-related emergency and office visits across all age categories and across all areas of residence. Moreover, we found that aboriginals were at a greater risk for COPD morbidity than for asthma. This may be related to the higher prevalences of cigarette smoking in aboriginal communities, which are, on average, two to three times higher those of nonaboriginal communities.¹⁸

Another important observation of our study was that despite the increased burden of asthma and COPD in the aboriginal community, aboriginal patients with these disorders had lower rates of specialist visits and spirometric testing than nonaboriginal patients. Aboriginals with asthma or COPD were 55% less likely to have seen a specialist and 66% less likely to have had spirometric testing than nonaboriginal patients during the study period. Although our study was not designed to evaluate "appropriateness of care," this finding in the presence of increased utilization of emergency and office services for asthma and COPD raises important concerns about access to appropriate care for these disorders in the aboriginal community.

Numerous explanations for the increased respiratory burden in the aboriginal community have been offered. Many aboriginal communities suffer from overcrowding and inadequate water and sewage systems,² exposing residents to harmful environmental toxins and infectious agents. The problem is exacerbated by a higher than expected prevalence of smoking and poor nutrition.¹ Moreover, since many aboriginals live in reservations and enclaves where there may be fewer outpatient clinics, they may also face impediments in access and availability of primary care, which may contribute to increased emergency use. Low income is also more prevalent among aboriginals than nonaboriginals. According to the 1996 Canadian Census, 73.4% of aboriginals earned < $20,000 per year compared with only 55.0% of nonaboriginals.⁴ In 1996, the average annual income for nonaboriginals was $25,414, while that for aboriginals was $15,699 (Canadian dollars).⁴ Aboriginals are also less likely to have formal postsecondary education, with only 2.2% receiving a university degree compared to 10.8% of nonaboriginals.⁵ While we tried to adjust for the differences in the socioeconomic status (SES) between aboriginals and nonaboriginals, we were able to use only a crude marker of SES in our analysis (ie, income $7,560); hence, residual confounding by SES may have been present. Future studies are needed to explore these factors in more detail and to determine their relative contributions to the rise in asthma/COPD morbidity among aboriginals.

Our study findings should be placed in the context of the Canadian health-care system, which ensures "universal" access to physician and hospital services. Aboriginals have the added advantage of having prescription medications fully paid for by the federal government, a benefit that does not exist for nonaboriginal residents except in cases of extreme poverty. Based on our data, it appears that an egalitarian health-care system cannot ensure similar patterns of use of asthma-related and COPD-related services between aboriginals and the rest of the population. This indicates that factors other than financial access barriers must be important in accounting for these differences.¹⁹

A potential problem of this study was that we relied exclusively on physician diagnosis for case ascertainment of asthma and COPD patients, which may have resulted in a diagnostic misclassification. Inclusion of acute respiratory conditions, such as acute respiratory tract infections, to the present data set did not materially change the results of our findings, suggesting that the misclassification was at worst nondifferential and would have led to an underestimation of the differences between aboriginals and nonaboriginals. Moreover, aboriginals residing in remote reserves receive primary as well as urgent care from nurse practitioners working in those areas. Since we did not capture these encounters, our findings likely underestimated the actual rates of office and emergency visits for asthma and COPD among aboriginals.

Despite the increased respiratory health burden experienced by the aboriginals in Canada, there is a paucity of data exploring the respiratory health needs of this population. This study found that aboriginals in Alberta suffer disproportionately from asthma and COPD and receive fewer specialist referrals and pulmonary function testing than nonaboriginals even after controlling for geographic location. There is an obvious need to increase attention to the unique needs of this population. Future research should focus on ways to reduce the burden of asthma and COPD in the aboriginal community and to explore potential barriers to quality health care for aboriginals with these disorders.

	Acknowledgements

 
The authors thank Ms. Casandra Higgs-Carey for assistance in preparing this article.

	Footnotes

 
Abbreviations: AHCIP = Alberta Health Care Insurance Plan; CI = confidence interval; ICD-9-CM = International Classification of Diseases; RR = relative risk; SES = socioeconomic status

The results and conclusions are strictly those of the authors and should not be attributed to any of the sponsoring agencies.

This project was sponsored in part through an unrestricted research grant from the Alberta Lung Association.

Dr. Sin is supported by a New Investigator Award from the Canadian Institutes of Health Research.

Received for publication April 16, 2001. Accepted for publication January 22, 2002.

	References

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1. MacMillan, HL, MacMillan, AB, Offord, DR, et al (1996) Aboriginal health. Can Med Assoc J 155,1569-1578[Abstract]
2. Fraser-Lee, NJ, Hessel, PA (1994) Acute respiratory infections in the Canadian native Indian population: a review. Can J Public Health 85,197-200[Medline]
3. Houston, CS, Weiler, RL, Habbick, BF (1979) Severity of lung disease in Indian children. Can Med Assoc J 120,1116-1121
4. Report of the Royal Commission on Aboriginal Peoples. Gathering strength. Ottawa: Canada: Canada Communication Group-Publishing, 1996; catalogue No. Z1-1991/1-3E
5. Statistics Canada: aboriginal peoples survey. Ottawa, Canada: Canadian Government Publications, 1994; catalogue No. 89–535, 1991
6. Senthilselvan, A, Habbick, BF (1995) Increased asthma hospitalizations among registered Indian children and adults in Saskatchewan, 1970–1989. J Clin Epidemiol 48,1277-1283[CrossRef][ISI][Medline]
7. Cydulka, RK, McFadden, ER, Emerman, CL, et al (1997) Patterns of hospitalization in elderly patients with asthma and chronic obstructive pulmonary disease. Am J Respir Crit Care Med 156,1807-1812[Abstract/Free Full Text]
8. Donahue, JG, Weiss, ST, Livingston, JM, et al (1997) Inhaled steroids and the risk of hospitalization for asthma. JAMA 277,887-891[Abstract]
9. Rawson, NS, Malcolm, E (1995) Validity of the ischemic heart disease and chronic obstructive pulmonary disease in the Saskatchewan health care files. Stat Med 14,2627-2643[ISI][Medline]
10. Hospers, JJ, Postma, DS, Rijcken, B, et al (2000) Histamine airway hyper-responsiveness and mortality from chronic obstructive pulmonary disease: a cohort study. Lancet 356,1313-1317[CrossRef][ISI][Medline]
11. Rosner, B (1995) Fundamentals of biostatistics. Wadsworth Publishing Belmont, CA.
12. SPSS Advanced Statistics 7.5. 1997 SPSS Chicago, IL.
13. Dudley, RA, Johansen, KL, Brand, R, et al (2000) Selective referral to high-volume hospitals: estimating potentially avoidable deaths. JAMA 283,1159-1166[Abstract/Free Full Text]
14. Keleher, H, Ellis, J (1996) Rural people utilising city hospitals: issues for service provision. Aust J Rural Health 4,144-1450[Medline]
15. Griffiths, C, Feder, G, Wedzicha, J, et al (1999) Feasibility of spirometry and reversibility testing for the identification of patients with chronic obstructive pulmonary disease on asthma registers in general practice. Respir Med 93,903-908[CrossRef][ISI][Medline]
16. Hemmelgarn, B, Ernst, P (1997) Airway function among Inuit primary school children in far northern Quebec. Am J Respir Crit Care Med 156,1870-1875[Abstract/Free Full Text]
17. Liu, LL, Stout, JW, Sullivan, M, et al (2000) Asthma and bronchiolitis hospitalizations among American Indian children. Arch Pediatr Adolesc Med 154,991-996[Abstract/Free Full Text]
18. Millar, WJ (1992) Place of birth and ethnic status: factors associated with smoking prevalence among Canadians. Stat Can Health Rep 4,7-24
19. Schulman, KA, Berlin, JA, Harless, W, et al (1999) The effect of race and sex on physicians’ recommendations for cardiac catheterization. N Engl J Med 25(340),618-626

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