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J Rheumatol. 2014 Apr;41(4):673-9. doi: 10.3899/jrheum.130667. Epub 2014 Mar 1.

Systemic autoimmune rheumatic disease prevalence in Canada: updated analyses across 7 provinces.

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From the Division of Clinical Epidemiology, and Divisions of Rheumatology, and Clinical Immunology/Allergy, Research Institute of the McGill University Health Centre (MUHC), Montreal, Quebec; Division of Rheumatology, University of British Columbia, Vancouver, British Columbia; Department of Epidemiology and Biostatistics, and Division of Rheumatology, McGill University; Dalhousie University and Queen Elizabeth II Health Sciences Center, Halifax, Nova Scotia; Departments of Medicine and Community Health Sciences, University of Manitoba, and Repository, Manitoba Centre for Health Policy, Winnipeg, Manitoba; Centre for Chronic Disease Prevention, Public Health Agency of Canada, Ottawa, Ontario; Division of Rheumatology, University of Calgary, Calgary, Alberta; Centre de recherche du CHU de Québec, Faculté de médecine, Université Laval, Quebec City, Quebec; Chronic Disease Surveillance Division, National Institute of Public Health of Québec; Health Surveillance Branch, Public Health Division, Alberta Health and Wellness, Edmonton, Alberta; Divisions of Rheumatology, and Clinical Immunology/Allergy, Research Institute of the MUHC; Canadian Arthritis Patient Alliance; Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada.



To estimate systemic autoimmune rheumatic disease (SARD) prevalence across 7 Canadian provinces using population-based administrative data evaluating both regional variations and the effects of age and sex.


Using provincial physician billing and hospitalization data, cases of SARD (systemic lupus erythematosus, scleroderma, primary Sjögren syndrome, polymyositis/dermatomyositis) were ascertained. Three case definitions (rheumatology billing, 2-code physician billing, and hospital diagnosis) were combined to derive a SARD prevalence estimate for each province, categorized by age, sex, and rural/urban status. A hierarchical Bayesian latent class regression model was fit to account for the imperfect sensitivity and specificity of each case definition. The model also provided sensitivity estimates of different case definition approaches.


Prevalence estimates for overall SARD ranged between 2 and 5 cases per 1000 residents across provinces. Similar demographic trends were evident across provinces, with greater prevalence in women and in persons over 45 years old. SARD prevalence in women over 45 was close to 1%. Overall sensitivity was poor, but estimates for each of the 3 case definitions improved within older populations and were slightly higher for men compared to women.


Our results are consistent with previous estimates and other North American findings, and provide results from coast to coast, as well as useful information about the degree of regional and demographic variations that can be seen within a single country. Our work demonstrates the usefulness of using multiple data sources, adjusting for the error in each, and providing estimates of the sensitivity of different case definition approaches.



[Indexed for MEDLINE]

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