Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.


Prevalence of Systemic Autoimmune Rheumatic Diseases(SARDs): Regional Comparisons

Bernatsky1,  S., Lix2,  L. M., Hanly3,  J. G., Hudson4,  M., Peschken5,  CA, Clarke1,  A. E., Pineau1,  C. A.

MUHC, Montreal, QC
University of Saskatchewn, Saskatoon, SK
Dalhousie University, Halifax, NS
McGill University, Montreal, QC
University of Manitoba, Winnipeg

Purpose:

Decision-makers are looking to administrative databases as a means of chronic disease surveillance, to aid in planning. Our purpose was to determine the prevalence of systemic autoimmune rheumatic diseases (SARDs) using population-based administrative data, and to compare results in three provinces representing central Canada (Quebec), western Canada (Manitoba) and the Maritimes (Nova Scotia).

Method:

Cases of SARDs (including systemic lupus, scleroderma, Sjogren's syndrome, and polymyositis/dermatomyositis) were ascertained using physician billing and hospitalization data from these provinces. We based our case ascertainment approach on three different case definition algorithms, combining information from each definition by using hierarchical Bayesian latent class regression models that account for the imperfect sensitivity and specificity of each case definition. Our methods allow us to estimate SARD prevalence and assess differences across patient demographics.

Results:

Using methods that account for the imperfect nature of both billing & hospitalization databases, we estimated the prevalence of SARDs to be approximately 2–3 cases per 1,000 residents. Prevalence was marginally higher in Manitoba at 2.8 cases/1,000(95% credible interval, CrI 2.7, 3.0), compared to Quebec at 2.6 cases/1,000(95% CrI 2.5, 2.6). Stratified prevalence estimates suggested similar demographic trends across provinces (i.e. greater prevalence in females-versus-males, and in persons of older age). The prevalence in older females approached or exceeded 1 in 100, which may reflect the high burden of primary Sjogren's syndrome in this group. Though stratified estimates were somewhat imprecise, they suggested a somewhat higher female:male ratio in Manitoba (approximately 8:1) compared to Nova Scotia(4:1) or Quebec(5:1). Adjusting for demographics, there was a greater prevalence in urban-versus-rural settings(less evident in Manitoba).

Conclusion:

Our results suggest that surveillance of some rheumatic diseases using administrative data may indeed be feasible and useful. Our work highlights the usefulness of using multiple data sources, adjusting for the error in each. Using these methods, we estimate that SARDs are as common as inflammatory bowel disease (estimated prevalence of about 2–3 cases/1000) & more common than HIV-related disease(1.8 cases/1000).

To cite this abstract, please use the following information:
Bernatsky, S., Lix, L. M., Hanly, J. G., Hudson, M., Peschken, CA, Clarke, A. E., et al; Prevalence of Systemic Autoimmune Rheumatic Diseases(SARDs): Regional Comparisons [abstract]. Arthritis Rheum 2009;60 Suppl 10 :783
DOI: 10.1002/art.25863

Abstract Supplement

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