- Email: [email protected]
Relative prevalence of Aboriginal patients in a Canadian uveitic population
Relative prevalence of Aboriginal patients in a Canadian uveitic population Mili Roy, MD ABSTRACT ● RÉSUMÉ Objective: To determine whether the prevalence of Aboriginal patients in a consecutive series of patients with uveitis differs significantly from the prevalence of Aboriginal persons in the general population. Design: Retrospective chart review. Participants: 133 consecutive patients with uveitis. Methods: The proportion of Aboriginal patients in a series of 133 consecutive patients with uveitis was compared to the proportion of Aboriginal persons within the general population to determine whether Aboriginal patients were under- or overrepresented in the population with uveitis, relative to their numbers in the population in general. The main outcome measure was the self-reported race of patients. The mean age, sex, and prior disease duration were also compared between Aboriginal and non-Aboriginal patients in the consecutive series. Results: There was no significant difference (p ⫽ 0.84) between the proportion of Aboriginal persons in the uveitis population studied (22 of 133; 16.5%) compared to general population census data (15.5% Aboriginal). Mean age at presentation was 36.8 years in the Aboriginal population versus 47.3 years in the control non-Aboriginal group (p ⫽ 0.01). Mean prior disease duration was 20.3 months in the Aboriginal population versus 21.1 months in the control group (p ⫽ 0.79). The gender proportion was 68.2% female in the Aboriginal group versus 53.2% female in the non-Aboriginal group (p ⫽ 0.02). Conclusions: This study finds no statistically significant difference between the prevalence of Aboriginal versus non-Aboriginal persons occurring within a consecutive series of uveitis patients as compared to the general population. Mean age at presentation was significantly younger, and female preponderance was significantly greater in the Aboriginal than in the non-Aboriginal group. Prior disease duration was comparable in the 2 groups. Objet : Déterminer si la prévalence des patients aborigènes dans une série de cas de patients atteints d’uvéite diffère de façon significative de la prévalence des personnes aborigènes dans la population en général. Nature : Examen rétrospectif des dossiers. Participants : 133 patients consécutifs atteints d’uvéite. Méthode : Le pourcentage des patients aborigènes dans une série de 133 patients consécutifs atteints d’uvéite a été comparé à celui des personnes aborigènes dans la population en général, afin d’établir si les patients aborigènes étaient sur ou sous représentés dans la population atteinte d’uvéite en regard de la population transversale. La principale mesure des résultats a porté sur la race autodéclarée des patients. La moyenne d’âge, la proportion des genres et la durée préalable de la maladie furent aussi comparées entre les patients témoins aborigènes et non aborigènes dans les séries consécutives. Résultats : Il n’y avait pas de différence significative (p ⫽ 0,84) entre le pourcentage des personnes aborigènes dans la population atteinte d’uvéite (22 sur 133, 16,5%) comparativement aux données du recensement (15,5% d’aborigènes). La moyenne d’âge au moment de la présentation était de 36,8 ans chez les aborigènes par rapport à 47,3 ans dans le groupe témoin (p ⫽ 0,01). La moyenne de durée préalable de la maladie était de 20,3 mois chez les aborigènes contre 21,1 mois dans le groupe témoin (p ⫽ 0,79). Le pourcentage des genres s’élevait à 68,2% de femmes dans le groupe aborigène en regard de 53,2% de femmes dans le groupe non aborigène (p ⫽ 0,02). Conclusions : Cette étude n’a pas démontré d’écart significatif entre la prévalence des aborigènes ou des non aborigènes survenant dans une série de patients atteints d’uvéite, comparativement à la population en général. La moyenne d’âge à la présentation était significativement plus jeune et la prépondérance féminine, significativement plus grande dans le groupe aborigène que dans celui non aborigène. La durée préalable de la maladie était comparable dans les deux groupes.
It is well recognized in evaluating uveitis that racial ancestry is a highly relevant consideration. Some uveitides occur more commonly in certain racial groups. Sarcoidosis-associated uveitis is more common in the African-American population than in the white American population.1 Behçet’s disease is seen more commonly in populations originating along the old Silk Route extending between Europe and Asia and along the Mediterranean basin to the Middle and Far East, including countries such as Italy, Turkey, Iran, Israel, Saudi Arabia, Korea, and Japan.2 In North America, the Aboriginal population bears particular historic and cultural significance as a group while representing a
rapidly growing segment of the overall population, with a growth of 45% between 1996 and 2006 as compared to a growth of 8% in the non-Aboriginal population during that time.3 Aboriginal peoples face unique issues regarding access to care and linguistic, cultural, and geographic concerns. Multiple studies suggest that a distinct predisposition and basis for certain autoimmune conditions exists within the Aboriginal population as opposed to the non-Aboriginal population. To date this has been more widely documented in the rheumatologic literature than in the ophthalmologic literature. North American First Nations populations have one of the highest prevalence rates of rheumatoid arthritis in the
From the University of Manitoba, Faculty of Medicine, Winnipeg, Man., and Goeyecare, Mississauga, Ont.
Can J Ophthalmol 2012;47:185–188
Originally received Oct. 6, 2011. Final revision Nov. 29, 2011. Accepted Jan. 9, 2012 Correspondence to Mili Roy, 3200 Erin Mills Pkwy, Mississauga ON L5L 1W8; [email protected]
0008-4182/11/$-see front matter © 2012 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.jcjo.2012.01.026
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Uveitis prevalence in Aboriginal Canadians—Roy world.4 Juvenile rheumatoid arthritis, vasculitis, and reactive arthritis also occur significantly more often in the Aboriginal population than in the Caucasian population according to a Canadian study.5 The Haida First Nation of British Columbia has one of the highest prevalence rates globally of both human leukocyte antigen (HLA) B27 positivity and of ankylosing spondylitis.6 By contrast, there is a relative paucity of published literature regarding the spectrum of uveitis in the North American Aboriginal population. The author was unable to document any such Canadian studies. A single American study from 1972 comprised a simple tabulation of all eye disease by diagnosis encountered in a specific population of American Indians. That study documented 5% of all ocular presentations as uveitis, primarily traumatic in nature, with a few cases of presumed ocular tuberculosis.7 Thus, despite the known significantly high prevalence of multiple autoimmune and rheumatologic conditions in the Aboriginal population, very little work has been done to date in the field of uveitis in this distinct group, aside from a few articles focused on specific uveitis entities. The current study examines the relative prevalence of Aboriginal versus non-Aboriginal persons in an uveitic population versus the general population in a central Canadian setting.
METHODS The study was performed as a retrospective chart review. Institutional review board and ethics committee approval was formally obtained from the Health Research Ethics Board, University of Manitoba, in addition to approval from the local provincial Assembly of Chiefs. It was deemed that individual patient consent was not required for the study design used. Charts of 140 consecutive patients with uveitis referred to a single subspecialty uveitis practice between December 2005 and March 2008 from a single geographic catchment area were reviewed. Of the charts, 7 were excluded because of incomplete information. For the remaining charts included in the study, patients’ ages, sex, prior disease durations, and self-reported race were documented (Tables 1 and 2). Patients reporting mixed race, comprising both Aboriginal and non-Aboriginal ancestry, were included in the Aboriginal group. The calculated proportion of Aboriginal patients in the uveitis cohort was compared statistically to the expected proportion of Aboriginal patients in the general population in the same region using Canadian census figures, to determine whether Aboriginal patients were under- or overrepresented in the uveitis population relative to the general population. Mean age, gender proportion, and prior disease duration were also statistically compared in the Aboriginal and non-Aboriginal, or control, groups of uveitis patients. The non-Aboriginal control group was composed of all nonAboriginal patients identified in the series of uveitis patients, whereas the Aboriginal group was composed of all
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Table 1—Baseline characteristics of Aboriginal uveitis patients Patient Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Age at Presentation
Sex
Prior Duration (mos.)
Racial Ancestry
53 50 N/A 10 39 28 33 53 45 38 30 13 9 27 35 53 25 33 51 57 44 47
M F F F F F F M F M F F F F M M F F M F F M
1 2 348 2 0.25 5 1 216 0.5 72 3 0.75 3 12 2 0.25 N/A 9 0.25 3.5 24 N/A
FN (Saulteaux) FN (Cree) Inuit FN (Cree) FN (Saulteaux) FN FN (Oji-Cree) FN Metis-Belgian Inuit FN FN (Ojibway) FN (Oji-Cree) FN (Ojibway) FN (Ojibway) FN (Cree) FN (Oji-Cree) Metis-Norwegian FN (Oji-Cree) Metis Cree-Scottish FN (Ojibway)
FN, First Nation (specific FN when known); N/A, not available.
Aboriginal patients identified in the same series. Duration of prior disease was defined as the duration of disease for each individual patient from the initial onset of his or her first episode of uveitis to the time of the first presentation to the author or to an alternative ophthalmologist within the same clinic as the author, whichever occurred first, such that detailed clinical information was available. When a discrete and well-defined prior disease-duration range was specified by a given patient rather than an exact single figure, the median value of the range was used for statistical analyses. Patients who could not specify the duration of a prior disease were omitted from that particular analysis and are identified accordingly.
RESULTS After exclusion of charts incomplete in terms of information regarding racial ancestry, the charts of 133 patients with uveitis were reviewed for inclusion in the study. Patients’ ages at presentation ranged from 9 to 57 years old (mean, 36.8 years) in the Aboriginal group as compared to 5 to 96 years old (mean, 47.3 years) in the non-Aboriginal group. The mean age at presentation was significantly younger by 10.5 years in the Aboriginal group versus the control group (p ⫽ 0.01). The duration of prior uveitis before first presentation, when known, ranged from 0.25 to 216 months (mean 20.3 months) in the Aboriginal group. In the non-Aboriginal group the duration of prior disease ranged from 0 (1 day) to 480 months (mean 21.1 months). The mean duration of prior disease before presentation did not differ significantly between the 2 groups (p ⫽ 0.79). Data regarding the duration of prior disease was either unavailable or not reliably quantified in 9 control non-Aboriginal patients and in 2 Aboriginal patients.
Uveitis prevalence in Aboriginal Canadians—Roy Table 2—Baseline characteristics of non-Aboriginal uveitis patients No.
Age at Presentation
Sex
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69
40 71 18 39 13 51 49 66 43 38 5 40 66 67 51 60 42 48 55 10 34 23 43 62 74 25 55 71 48 53 88 22 45 28 36 53 35 32 23 38 60 44 43 39 59 50 13 55 73 54 51 57 51 51 29 34 53 69 58 64 56 58 25 56 26 48 60 59 47
F F M F M F F F F F F F F M F F F M F F M F M F M M F M M F F F F M M M M M F F F M F F F F F M F F M F F M M M M F M F M F M F F F F F M
Prior Duration (mos.) 120 24 0.25 5 6 24 4 N/A N/A 12 40 10 432 5 4 2 24 23 1 97 216 144 1.5 2 7 48 0 (1 day) 1.5 N/A 152 1 84 36 10 3 12 0.33 0.25 (5 days) 0.25 24 24 0.33 12 4 1.5 18-24 14 N/A 7 10 264 3 48 0.5 2 4 120-144 48 12 5 7 240 12 0.25 6 12-24 5 36 1
Table 2—(continued) No.
Age at Presentation
Sex
Prior Duration (mos.)
Racial Ancestry
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111
42 37 41 35 46 69 30 91 12 20 56 32 79 68 51 21 30 52 38 79 29 70 6 42 48 N/A 53 35 96 N/A 69 43 65 51 80 71 34 56 33 76 50 23
M M M M F M M F M M M M F M F F M M M M M F M F M F M M F F F M F F F M M M M M F F
0.125 (3-4 days) 4 0.25 24 2.5 6.5 6 N/A 3 1.5 0.25 N/A 10 10 5 216 0.125 (3-4 days) 30 48 0.75 240 20 7 480 0.75 N/A 120 9 10 N/A N/A 6.5 12 48 0.125 (3-4 days) 0.25 0.125 (3-4 days) 0.25 0.125 (3-4 days) 12 0.5 36
Asian Caucasian Caucasian European European European Asian European European Caucasian Caucasian Eurasian West Indian/European African Asian Caucasian Asian European African Caucasian European Caucasian Caucasian Caucasian European Caucasian European European/Latin American European African European Caucasian European European European European European European European European European European
Racial Ancestry European European European European European European European European West Indian/African European Caucasian Caucasian European European European European European Caucasian European South American/European Latin American/Caucasian European European European European African Asian European African Asian European African European European European Asian Caucasian European European European Asian European Asian Caucasian Caucasian European European Caucasian European European European Caucasian European Caucasian European Caucasian European European European European European European European Asian Asian European Caucasian European European
Calculations were made after these particular patients had been excluded from the analyses of the duration of prior disease. The gender proportions gender measured 68.2% female and 31.8% male in the Aboriginal group versus 53.2% female and 46.8% male in the non-Aboriginal group. The preponderance of females was significantly greater in the Aboriginal group (odds ratio, 1.88) than in the non-Aboriginal group (p ⫽ 0.02). Of the 133 patients reviewed in total, 22 (16.5%) patients were found to be Aboriginal and 111 (83.5%) were nonAboriginal. Census figures for the same region documented 15.5% of the general cross-sectional population to be Aboriginal and 84.5% non-Aboriginal.8 By 2 analysis, there was no statistically significant difference between the proportion of Aboriginal persons encountered in the uveitic population compared to the census-tabulated proportion of Aboriginal persons in the general population of the same region (p ⫽ 0.84). Aboriginal persons identified represented various ancestries, including Inuit, Metis, and multiple First Nations, including Cree, Ojibway, Oji-Cree, and Saulteaux. Of these CAN J OPHTHALMOL—VOL. 47, NO. 2, APRIL 2012
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Uveitis prevalence in Aboriginal Canadians—Roy patients, 3 self-reported as First Nation but did not further define a specific First Nation of origin.
DISCUSSION There is ample published evidence that the epidemiology of rheumatic disorders in the North American Aboriginal population is significantly different from that of the general North American cross-sectional population.9 The prevalence of some autoimmune conditions, such as rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, and HLAB27 positivity, have been found to be significantly higher in some North American Aboriginal populations than in other populations worldwide. It is also known that these and certain other rheumatologic and autoimmune diseases are associated with uveitis and other ocular inflammatory disorders. Despite numerous studies documented in the rheumatologic literature, corresponding studies analyzing the prevalence of uveitis in the North American Aboriginal population have been largely lacking to date. This study finds no statistically significant difference between the prevalence of Aboriginal versus non-Aboriginal persons occurring within a consecutive series of uveitis patients, as compared to the prevalence of Aboriginal versus non-Aboriginal persons occurring in the general population for the same catchment area using population census figures. Mean age at presentation was significantly younger and female preponderance was greater in the Aboriginal group than in the non-Aboriginal group. Despite unique issues facing some Aboriginal patients regarding access to health care due to considerations of geography, culture, language, or other factors, the duration of prior disease was comparable in both groups. This would suggest no significant difference in known duration of uveitis in Aboriginal versus non-Aboriginal patients at the time of initial referral and presentation to the main dedicated tertiary uveitis service in the region. On the basis of these data, conclusions cannot be drawn regarding the duration of prior disease when patients first presented to a primary ophthalmic care provider. This study was limited by numerous constraints, including a small sample size. Nevertheless, statistically significant comparisons can be drawn. Restrictions in the available data necessitated indirect inference of the relative prevalence of uveitis in the Aboriginal versus the non-Aboriginal population rather than allowing direct calculation of prevalence rates in each individual group so they could be compared. Furthermore, because the study population derived from a single tertiary–level, subspecialty uveitisfocused practice, a selection bias may have been introduced. For example, more complex cases might have been more highly represented than they would have been in a truly random sampling of all patients experiencing uveitis in the population in question. Longer duration of previous disease might also have occurred than might be documented in studying first contact with primary- or second-
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ary-level health care workers. However, this bias applies equally to both the Aboriginal and the non-Aboriginal groups, thus mitigating any skewing of results on this basis when comparing the 2 groups. It is also known from prior studies of some autoimmune diseases, particularly in the literature concerning rheumatologic disorders, that the prevalence of a single disease entity can vary greatly between different Aboriginal groups, including significant differences in rates between First Nation people and Inuit people or between different various First Nation groups. Given the significant paucity of literature addressing uveitis occurring in the North American Aboriginal population, it behooves the ophthalmologic community, in collaboration with the Aboriginal community, to engage in further studies in this field to better our understanding of this complex group of diseases in the context of this population and its subgroups. Particularly in light of findings emerging in the rheumatologic literature that address various rheumatologic conditions in the North American Aboriginal population and the interrelatedness of some noninfectious uveitides with certain of these autoimmune and rheumatologic disorders, the need for further study is highlighted.
Acknowledgements: I acknowledge my statistician M. L. Schmuck (affiliated with The Programme for Educational Research and Development, McMaster University, Hamilton, Ontario), who contributed significantly to the analyses performed. Disclosure: The author has no proprietary or commercial interest in the materials discussed in this article. REFERENCES 1. Siltzbach LE, James DG, Neville E, et al. Course and prognosis of sarcoidosis around the world. Am J Med. 1974;57:847-52. 2. Bonfioli AA, Orefice F. Behçet’s disease. Semin Ophthalmol. 2005;20: 199-206. 3. Statistics Canada 2006 Census. Aboriginal Peoples: Release No. 5. Jan. 15, 2008, updated May 25, 2011. Available online at www12.statcan.ca/ census-recensement/2006/rt-td/ap-pa-eng.cfm. Accessed Oct. 2, 2011. 4. El-Gabalawy HS, Robinson DB, Daha NA, et al. Non-HLA genes modulate the risk of rheumatoid arthritis associated with HLA-DRB1 in a susceptible North American Native population. Genes Immun. 2011;12: 568-74. 5. Barnabe C, Elias B, Bartlett J, et al. Arthritis in Aboriginal Manitobans: Evidence for a high burden of disease. J Rheumatol. 2008;35:1145-50. E-pub Apr. 15, 2008. 6. Gofton JP, Chalmers A, Price GE, et al. HL-A 27 and ankylosing spondylitis in B.C. Indians. J Rheumatol. 1984;11:572-3. 7. Bettman JW Jr. Eye disease among American Indians of the Southwest. I. Overall analysis. Arch Ophthal. 1972;88:263-8. 8. Statistics Canada 2006 Census. Aboriginal identity population by age groups, medial age and sex: 2006 counts for both sexes, for Canada, provinces and territories, and census metropolitan areas and census agglomerations: 20% sample data, Manitoba. Updated Oct. 6, 2010. Available online at www.12.statcan.ca/census-recensement/2006/dp-pd/hlt/ 97558/pages/page.cfm?Lang⫽E&Geo⫽CMA&Code⫽46&Table⫽1& Data⫽Count&Sex⫽1&Age⫽1&StartRec⫽1&Sort⫽2&Display⫽Page. Accessed Apr. 12, 2011. 9. Peschken CA, Esdaile JM. Rheumatic diseases in North America’s indigenous peoples. Semin Arthritis Rheum. 1999;28:368-91.
It is well recognized in evaluating uveitis that racial ancestry is a highly relevant consideration. Some uveitides occur more commonly in certain racial groups. Sarcoidosis-associated uveitis is more common in the African-American population than in the white American population.1 Behçet’s disease is seen more commonly in populations originating along the old Silk Route extending between Europe and Asia and along the Mediterranean basin to the Middle and Far East, including countries such as Italy, Turkey, Iran, Israel, Saudi Arabia, Korea, and Japan.2 In North America, the Aboriginal population bears particular historic and cultural significance as a group while representing a
rapidly growing segment of the overall population, with a growth of 45% between 1996 and 2006 as compared to a growth of 8% in the non-Aboriginal population during that time.3 Aboriginal peoples face unique issues regarding access to care and linguistic, cultural, and geographic concerns. Multiple studies suggest that a distinct predisposition and basis for certain autoimmune conditions exists within the Aboriginal population as opposed to the non-Aboriginal population. To date this has been more widely documented in the rheumatologic literature than in the ophthalmologic literature. North American First Nations populations have one of the highest prevalence rates of rheumatoid arthritis in the
From the University of Manitoba, Faculty of Medicine, Winnipeg, Man., and Goeyecare, Mississauga, Ont.
Can J Ophthalmol 2012;47:185–188
Originally received Oct. 6, 2011. Final revision Nov. 29, 2011. Accepted Jan. 9, 2012 Correspondence to Mili Roy, 3200 Erin Mills Pkwy, Mississauga ON L5L 1W8; [email protected]
0008-4182/11/$-see front matter © 2012 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.jcjo.2012.01.026
CAN J OPHTHALMOL—VOL. 47, NO. 2, APRIL 2012
185
Uveitis prevalence in Aboriginal Canadians—Roy world.4 Juvenile rheumatoid arthritis, vasculitis, and reactive arthritis also occur significantly more often in the Aboriginal population than in the Caucasian population according to a Canadian study.5 The Haida First Nation of British Columbia has one of the highest prevalence rates globally of both human leukocyte antigen (HLA) B27 positivity and of ankylosing spondylitis.6 By contrast, there is a relative paucity of published literature regarding the spectrum of uveitis in the North American Aboriginal population. The author was unable to document any such Canadian studies. A single American study from 1972 comprised a simple tabulation of all eye disease by diagnosis encountered in a specific population of American Indians. That study documented 5% of all ocular presentations as uveitis, primarily traumatic in nature, with a few cases of presumed ocular tuberculosis.7 Thus, despite the known significantly high prevalence of multiple autoimmune and rheumatologic conditions in the Aboriginal population, very little work has been done to date in the field of uveitis in this distinct group, aside from a few articles focused on specific uveitis entities. The current study examines the relative prevalence of Aboriginal versus non-Aboriginal persons in an uveitic population versus the general population in a central Canadian setting.
METHODS The study was performed as a retrospective chart review. Institutional review board and ethics committee approval was formally obtained from the Health Research Ethics Board, University of Manitoba, in addition to approval from the local provincial Assembly of Chiefs. It was deemed that individual patient consent was not required for the study design used. Charts of 140 consecutive patients with uveitis referred to a single subspecialty uveitis practice between December 2005 and March 2008 from a single geographic catchment area were reviewed. Of the charts, 7 were excluded because of incomplete information. For the remaining charts included in the study, patients’ ages, sex, prior disease durations, and self-reported race were documented (Tables 1 and 2). Patients reporting mixed race, comprising both Aboriginal and non-Aboriginal ancestry, were included in the Aboriginal group. The calculated proportion of Aboriginal patients in the uveitis cohort was compared statistically to the expected proportion of Aboriginal patients in the general population in the same region using Canadian census figures, to determine whether Aboriginal patients were under- or overrepresented in the uveitis population relative to the general population. Mean age, gender proportion, and prior disease duration were also statistically compared in the Aboriginal and non-Aboriginal, or control, groups of uveitis patients. The non-Aboriginal control group was composed of all nonAboriginal patients identified in the series of uveitis patients, whereas the Aboriginal group was composed of all
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Table 1—Baseline characteristics of Aboriginal uveitis patients Patient Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Age at Presentation
Sex
Prior Duration (mos.)
Racial Ancestry
53 50 N/A 10 39 28 33 53 45 38 30 13 9 27 35 53 25 33 51 57 44 47
M F F F F F F M F M F F F F M M F F M F F M
1 2 348 2 0.25 5 1 216 0.5 72 3 0.75 3 12 2 0.25 N/A 9 0.25 3.5 24 N/A
FN (Saulteaux) FN (Cree) Inuit FN (Cree) FN (Saulteaux) FN FN (Oji-Cree) FN Metis-Belgian Inuit FN FN (Ojibway) FN (Oji-Cree) FN (Ojibway) FN (Ojibway) FN (Cree) FN (Oji-Cree) Metis-Norwegian FN (Oji-Cree) Metis Cree-Scottish FN (Ojibway)
FN, First Nation (specific FN when known); N/A, not available.
Aboriginal patients identified in the same series. Duration of prior disease was defined as the duration of disease for each individual patient from the initial onset of his or her first episode of uveitis to the time of the first presentation to the author or to an alternative ophthalmologist within the same clinic as the author, whichever occurred first, such that detailed clinical information was available. When a discrete and well-defined prior disease-duration range was specified by a given patient rather than an exact single figure, the median value of the range was used for statistical analyses. Patients who could not specify the duration of a prior disease were omitted from that particular analysis and are identified accordingly.
RESULTS After exclusion of charts incomplete in terms of information regarding racial ancestry, the charts of 133 patients with uveitis were reviewed for inclusion in the study. Patients’ ages at presentation ranged from 9 to 57 years old (mean, 36.8 years) in the Aboriginal group as compared to 5 to 96 years old (mean, 47.3 years) in the non-Aboriginal group. The mean age at presentation was significantly younger by 10.5 years in the Aboriginal group versus the control group (p ⫽ 0.01). The duration of prior uveitis before first presentation, when known, ranged from 0.25 to 216 months (mean 20.3 months) in the Aboriginal group. In the non-Aboriginal group the duration of prior disease ranged from 0 (1 day) to 480 months (mean 21.1 months). The mean duration of prior disease before presentation did not differ significantly between the 2 groups (p ⫽ 0.79). Data regarding the duration of prior disease was either unavailable or not reliably quantified in 9 control non-Aboriginal patients and in 2 Aboriginal patients.
Uveitis prevalence in Aboriginal Canadians—Roy Table 2—Baseline characteristics of non-Aboriginal uveitis patients No.
Age at Presentation
Sex
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69
40 71 18 39 13 51 49 66 43 38 5 40 66 67 51 60 42 48 55 10 34 23 43 62 74 25 55 71 48 53 88 22 45 28 36 53 35 32 23 38 60 44 43 39 59 50 13 55 73 54 51 57 51 51 29 34 53 69 58 64 56 58 25 56 26 48 60 59 47
F F M F M F F F F F F F F M F F F M F F M F M F M M F M M F F F F M M M M M F F F M F F F F F M F F M F F M M M M F M F M F M F F F F F M
Prior Duration (mos.) 120 24 0.25 5 6 24 4 N/A N/A 12 40 10 432 5 4 2 24 23 1 97 216 144 1.5 2 7 48 0 (1 day) 1.5 N/A 152 1 84 36 10 3 12 0.33 0.25 (5 days) 0.25 24 24 0.33 12 4 1.5 18-24 14 N/A 7 10 264 3 48 0.5 2 4 120-144 48 12 5 7 240 12 0.25 6 12-24 5 36 1
Table 2—(continued) No.
Age at Presentation
Sex
Prior Duration (mos.)
Racial Ancestry
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111
42 37 41 35 46 69 30 91 12 20 56 32 79 68 51 21 30 52 38 79 29 70 6 42 48 N/A 53 35 96 N/A 69 43 65 51 80 71 34 56 33 76 50 23
M M M M F M M F M M M M F M F F M M M M M F M F M F M M F F F M F F F M M M M M F F
0.125 (3-4 days) 4 0.25 24 2.5 6.5 6 N/A 3 1.5 0.25 N/A 10 10 5 216 0.125 (3-4 days) 30 48 0.75 240 20 7 480 0.75 N/A 120 9 10 N/A N/A 6.5 12 48 0.125 (3-4 days) 0.25 0.125 (3-4 days) 0.25 0.125 (3-4 days) 12 0.5 36
Asian Caucasian Caucasian European European European Asian European European Caucasian Caucasian Eurasian West Indian/European African Asian Caucasian Asian European African Caucasian European Caucasian Caucasian Caucasian European Caucasian European European/Latin American European African European Caucasian European European European European European European European European European European
Racial Ancestry European European European European European European European European West Indian/African European Caucasian Caucasian European European European European European Caucasian European South American/European Latin American/Caucasian European European European European African Asian European African Asian European African European European European Asian Caucasian European European European Asian European Asian Caucasian Caucasian European European Caucasian European European European Caucasian European Caucasian European Caucasian European European European European European European European Asian Asian European Caucasian European European
Calculations were made after these particular patients had been excluded from the analyses of the duration of prior disease. The gender proportions gender measured 68.2% female and 31.8% male in the Aboriginal group versus 53.2% female and 46.8% male in the non-Aboriginal group. The preponderance of females was significantly greater in the Aboriginal group (odds ratio, 1.88) than in the non-Aboriginal group (p ⫽ 0.02). Of the 133 patients reviewed in total, 22 (16.5%) patients were found to be Aboriginal and 111 (83.5%) were nonAboriginal. Census figures for the same region documented 15.5% of the general cross-sectional population to be Aboriginal and 84.5% non-Aboriginal.8 By 2 analysis, there was no statistically significant difference between the proportion of Aboriginal persons encountered in the uveitic population compared to the census-tabulated proportion of Aboriginal persons in the general population of the same region (p ⫽ 0.84). Aboriginal persons identified represented various ancestries, including Inuit, Metis, and multiple First Nations, including Cree, Ojibway, Oji-Cree, and Saulteaux. Of these CAN J OPHTHALMOL—VOL. 47, NO. 2, APRIL 2012
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Uveitis prevalence in Aboriginal Canadians—Roy patients, 3 self-reported as First Nation but did not further define a specific First Nation of origin.
DISCUSSION There is ample published evidence that the epidemiology of rheumatic disorders in the North American Aboriginal population is significantly different from that of the general North American cross-sectional population.9 The prevalence of some autoimmune conditions, such as rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, and HLAB27 positivity, have been found to be significantly higher in some North American Aboriginal populations than in other populations worldwide. It is also known that these and certain other rheumatologic and autoimmune diseases are associated with uveitis and other ocular inflammatory disorders. Despite numerous studies documented in the rheumatologic literature, corresponding studies analyzing the prevalence of uveitis in the North American Aboriginal population have been largely lacking to date. This study finds no statistically significant difference between the prevalence of Aboriginal versus non-Aboriginal persons occurring within a consecutive series of uveitis patients, as compared to the prevalence of Aboriginal versus non-Aboriginal persons occurring in the general population for the same catchment area using population census figures. Mean age at presentation was significantly younger and female preponderance was greater in the Aboriginal group than in the non-Aboriginal group. Despite unique issues facing some Aboriginal patients regarding access to health care due to considerations of geography, culture, language, or other factors, the duration of prior disease was comparable in both groups. This would suggest no significant difference in known duration of uveitis in Aboriginal versus non-Aboriginal patients at the time of initial referral and presentation to the main dedicated tertiary uveitis service in the region. On the basis of these data, conclusions cannot be drawn regarding the duration of prior disease when patients first presented to a primary ophthalmic care provider. This study was limited by numerous constraints, including a small sample size. Nevertheless, statistically significant comparisons can be drawn. Restrictions in the available data necessitated indirect inference of the relative prevalence of uveitis in the Aboriginal versus the non-Aboriginal population rather than allowing direct calculation of prevalence rates in each individual group so they could be compared. Furthermore, because the study population derived from a single tertiary–level, subspecialty uveitisfocused practice, a selection bias may have been introduced. For example, more complex cases might have been more highly represented than they would have been in a truly random sampling of all patients experiencing uveitis in the population in question. Longer duration of previous disease might also have occurred than might be documented in studying first contact with primary- or second-
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ary-level health care workers. However, this bias applies equally to both the Aboriginal and the non-Aboriginal groups, thus mitigating any skewing of results on this basis when comparing the 2 groups. It is also known from prior studies of some autoimmune diseases, particularly in the literature concerning rheumatologic disorders, that the prevalence of a single disease entity can vary greatly between different Aboriginal groups, including significant differences in rates between First Nation people and Inuit people or between different various First Nation groups. Given the significant paucity of literature addressing uveitis occurring in the North American Aboriginal population, it behooves the ophthalmologic community, in collaboration with the Aboriginal community, to engage in further studies in this field to better our understanding of this complex group of diseases in the context of this population and its subgroups. Particularly in light of findings emerging in the rheumatologic literature that address various rheumatologic conditions in the North American Aboriginal population and the interrelatedness of some noninfectious uveitides with certain of these autoimmune and rheumatologic disorders, the need for further study is highlighted.
Acknowledgements: I acknowledge my statistician M. L. Schmuck (affiliated with The Programme for Educational Research and Development, McMaster University, Hamilton, Ontario), who contributed significantly to the analyses performed. Disclosure: The author has no proprietary or commercial interest in the materials discussed in this article. REFERENCES 1. Siltzbach LE, James DG, Neville E, et al. Course and prognosis of sarcoidosis around the world. Am J Med. 1974;57:847-52. 2. Bonfioli AA, Orefice F. Behçet’s disease. Semin Ophthalmol. 2005;20: 199-206. 3. Statistics Canada 2006 Census. Aboriginal Peoples: Release No. 5. Jan. 15, 2008, updated May 25, 2011. Available online at www12.statcan.ca/ census-recensement/2006/rt-td/ap-pa-eng.cfm. Accessed Oct. 2, 2011. 4. El-Gabalawy HS, Robinson DB, Daha NA, et al. Non-HLA genes modulate the risk of rheumatoid arthritis associated with HLA-DRB1 in a susceptible North American Native population. Genes Immun. 2011;12: 568-74. 5. Barnabe C, Elias B, Bartlett J, et al. Arthritis in Aboriginal Manitobans: Evidence for a high burden of disease. J Rheumatol. 2008;35:1145-50. E-pub Apr. 15, 2008. 6. Gofton JP, Chalmers A, Price GE, et al. HL-A 27 and ankylosing spondylitis in B.C. Indians. J Rheumatol. 1984;11:572-3. 7. Bettman JW Jr. Eye disease among American Indians of the Southwest. I. Overall analysis. Arch Ophthal. 1972;88:263-8. 8. Statistics Canada 2006 Census. Aboriginal identity population by age groups, medial age and sex: 2006 counts for both sexes, for Canada, provinces and territories, and census metropolitan areas and census agglomerations: 20% sample data, Manitoba. Updated Oct. 6, 2010. Available online at www.12.statcan.ca/census-recensement/2006/dp-pd/hlt/ 97558/pages/page.cfm?Lang⫽E&Geo⫽CMA&Code⫽46&Table⫽1& Data⫽Count&Sex⫽1&Age⫽1&StartRec⫽1&Sort⫽2&Display⫽Page. Accessed Apr. 12, 2011. 9. Peschken CA, Esdaile JM. Rheumatic diseases in North America’s indigenous peoples. Semin Arthritis Rheum. 1999;28:368-91.