Rheumatoid arthritis prevalence in Quebec

BMC Research Notes, Dec 2014

Background To estimate rheumatoid arthritis (RA) prevalence in Quebec using administrative health data, comparing across regions. Methods Cases of RA were ascertained from physician billing and hospitalization data, 1992–2008. We used three case definitions: 1) ≥ 2 billing diagnoses, submitted by any physician, ≥ 2 months apart, but within 2 years; 2) ≥ 1 diagnosis, by a rheumatologist; 3) ≥1 hospitalization diagnosis (all based on ICD-9 code 714, and ICD-10 code M05). We combined data across these three case definitions, using Bayesian hierarchical latent class models to estimate RA prevalence, adjusting for the imperfect sensitivity and specificity of the data. We compared urban versus rural regions. Results Using our case definitions and no adjustment for error, we defined 75,760 cases for an over-all RA prevalence of 9.9 per thousand residents. After adjusting for the imperfect sensitivity and specificity of our case definition algorithms, we estimated Quebec RA prevalence at 5.6 per 1000 females and 4.1 per 1000 males. The adjusted RA prevalence estimates for older females were the highest for any demographic group (9.9 cases per 1,000), and were similar in rural and urban regions. In younger males and females, and in older males, RA prevalence estimates were lower in rural versus urban areas. Conclusions Without adjustment for error inherent in administrative databases, RA prevalence in Quebec was approximately 1%, while adjusted estimates are approximately half that. The lower prevalence in rural areas, seen for most demographic groups, may suggest either true regional variations in RA risk, or under-ascertainment of cases in rural Quebec.

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Rheumatoid arthritis prevalence in Quebec

BMC Research Notes Rheumatoid arthritis prevalence in Quebec Sasha Bernatsky 0 1 Alaa Dekis 0 Marie Hudson 2 Christian A Pineau 0 Gilles Boire 6 Paul R Fortin 5 Louis Bessette 4 5 Sonia Jean 3 Ann L Chetaille 5 Patrick Belisle 1 Louise Bergeron 8 Debbie Ehrmann Feldman 7 Lawrence Joseph 1 0 Division of Rheumatology, McGill University Health Centre , Montreal, Quebec , Canada 1 Division of Clinical Epidemiology, McGill University Health Centre , 687 Pine Avenue West, V-Building, V2.09, Montreal, QC H3A 1A1 , Canada 2 Jewish General Hospital and Lady David Research Institute , Montreal, Quebec , Canada 3 Chronic Disease Surveillance Division, National Institute of Public Health of Québec , Quebec City, Quebec , Canada 4 Rheumatology Department, Centre Hospitalier Universitaire de Québec (CHUQ) Research Centre , Quebec City, Quebec , Canada 5 Faculty of Medicine, Laval University , Quebec City, Quebec , Canada 6 Department of Medicine, University of Sherbrooke , Sherbrooke, Quebec , Canada 7 Université de Montréal, École de réadaptation , Montreal, Quebec , Canada 8 Canadian Arthritis Patient Alliance , Ile Perrot, Quebec , Canada Background: To estimate rheumatoid arthritis (RA) prevalence in Quebec using administrative health data, comparing across regions. Methods: Cases of RA were ascertained from physician billing and hospitalization data, 1992-2008. We used three case definitions: 1) ≥ 2 billing diagnoses, submitted by any physician, ≥ 2 months apart, but within 2 years; 2) ≥ 1 diagnosis, by a rheumatologist; 3) ≥1 hospitalization diagnosis (all based on ICD-9 code 714, and ICD-10 code M05). We combined data across these three case definitions, using Bayesian hierarchical latent class models to estimate RA prevalence, adjusting for the imperfect sensitivity and specificity of the data. We compared urban versus rural regions. Results: Using our case definitions and no adjustment for error, we defined 75,760 cases for an over-all RA prevalence of 9.9 per thousand residents. After adjusting for the imperfect sensitivity and specificity of our case definition algorithms, we estimated Quebec RA prevalence at 5.6 per 1000 females and 4.1 per 1000 males. The adjusted RA prevalence estimates for older females were the highest for any demographic group (9.9 cases per 1,000), and were similar in rural and urban regions. In younger males and females, and in older males, RA prevalence estimates were lower in rural versus urban areas. Conclusions: Without adjustment for error inherent in administrative databases, RA prevalence in Quebec was approximately 1%, while adjusted estimates are approximately half that. The lower prevalence in rural areas, seen for most demographic groups, may suggest either true regional variations in RA risk, or under-ascertainment of cases in rural Quebec. Arthritis; Epidemiology; Rheumatoid Arthritis Background There is growing interest in developing tools and methods for the surveillance of chronic rheumatic diseases, using existing resources such as administrative health databases. Comparing disease prevalence across certain regions might be of particular interest; for example, for historic and geographic reasons, individuals in some rural regions of Quebec have been somewhat isolated from other parts of the province. This has many potential effects; one may be differences in genetic make-up, and other may be variations in access to care. Differences in access to care might mean that the sensitivity and specificity of administrative data-based case definitions may vary across rural versus urban areas, and even within rural areas, from one sub-region to another. Our objective was to estimate the prevalence of rheumatoid arthritis (RA) in Quebec based on administrative health data, and to determine if RA prevalence estimates were any different in urban versus rural regions. We also performed exploratory sub-analyses in two regions which have been particularly isolated geographically. Since administrative data rely on medical contact in order to ascertain cases, the RA prevalence estimates in these very isolated areas (where access to care is presumably lower) might be different from the rest of rural Quebec. On the other hand, very isolated regions generally tend to have reduced genetic variation [ 1-3 ] which theoretically could alter RA risk (compared to the rest of Quebec), since genetic susceptibility is a risk factor (albeit a complex one) for RA [ 4 ]. We sought to provide new data regarding the estimates of RA prevalence across regions in Quebec, including these very isolated regions. The methodological approach chosen in this paper offers a means of dealing with the imperfect nature of administrative data, as will be seen. Methods We used hospitalization and physician billing data for all of Quebec (approximately 7.6 million residents), across 1992–2008, to estimate the prevalence of existing RA cases in 2008. The data include hospitalization discharge diagnoses (...truncated)


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Sasha Bernatsky, Alaa Dekis, Marie Hudson, Christian A Pineau, Gilles Boire, Paul R Fortin, Louis Bessette, Sonia Jean, Ann L Chetaille, Patrick Belisle, Louise Bergeron, Debbie Ehrmann Feldman, Lawrence Joseph. Rheumatoid arthritis prevalence in Quebec, BMC Research Notes, 2014, pp. 937, Volume 7, Issue 1, DOI: 10.1186/1756-0500-7-937