Trends In Incidence and Mortality In Rheumatoid Arthritis and Systemic Autoimmune Rheumatic Diseases In Quebec, Canada: A Population-Based Study

Sonia Jean¹, Philippe Gamache², Marie Hudson³, Louis Bessette⁴, Paul R. Fortin⁵, Gilles Boire⁶ and Sasha Bernatsky⁷, ¹Chronic disease surveillence division, National Institute of public health of Quebec, Quebec, QC, Canada, ²Chronic disease surveillance division, National institute of public health of Quebec, Quebec, QC, Canada, ³Rheumatology, Lady David Institute for Medical Research and Jewish General Hospital, Montreal, QC, Canada, ⁴Centre Hospitalier Universitaire de Québec, pavillon CHUL, Sainte-Foy, QC, Canada, ⁵Medicine, Centre de Recherche du Chu de Québec et Université Laval, Quebec City, QC, Canada, ⁶Rheumatology Division, Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC, Canada, ⁷Clinical Epidemiology, Research Institute of the McGill University Health Ctre, Montreal, QC, Canada

Meeting: 2013 ACR/ARHP Annual Meeting

Keywords: administrative databases, Epidemiologic methods, morbidity and mortality and rheumatic disease

Session Information

Session Title: ACR/ARHP Combined Epidemiology Abstract Session

Session Type: Combined Abstract Sessions

Background/Purpose:

Health administrative data (HAD) are a potentially efficient to conduct population-based research and are increasingly used to develop chronic disease surveillance indicators. Examining trends in incidence and mortality over time can assist in monitoring disease burden and evaluating the effectiveness of treatment. The aim of this study was to explore time trends in incidence and mortality for rheumatoid arthritis (RA) and selected systemic autoimmune rheumatic diseases (SARD).

Methods:

Using case definitions for HAD available in Quebec, Canada, 2 population-based cohorts for RA and SARD (1996-2010) were defined. To identify incident cases, a «run-in» period of 5 years (1996-2000) was used to exclude prevalent cases. Age and sex-specific incidence rates were calculated using the number of incident cases as the numerator and the counts of population eligible for health insurance registry as the denominator. Age-standardized incidence rates (SIR) were calculated using the 2001 age-structure of the Quebec population. Health insurance registry file was also used to identify deaths among 2 cohorts and, for each year, mortality rates in each cohort were compared with mortality rates in the general population using standardized mortality rate ratios (SRR). Joinpoint and negative binomial regression analyses were used to test for linear change in incidence rates and SRR.

Results:

Prevalence of RA and SARD in 2009 were estimated at 1100.7 and 529.8 per 100,000 persons, respectively. For RA, 69.2% of cases were females, while for SARD, this percentage was 73.5%. The linear trends in SIR did not show significant change over the study period (RA p-value=0.3613, SARD p-value 0.0510) (Fig. 1 and 2). The mortality rate in RA and SARD patients was significantly higher than the expected rate in general population (2009: RA SRR=1.32, SARD SRR=1.95), and no significant improvement was observed (Fig. 3).

Conclusion:

No secular trends in SIR of RA and SARD were observed over time. The mortality was substantially higher in RA and SARD compared to general population, and remained so over the study period. This suggests further efforts are needed to optimize long-term outcomes in these diseases.

FIGURE 1 SIR for RA, Quebec, 2001-2010

FIGURE 2 SIR for SARD, Quebec, 2001-2010

FIGURE 3 SRR, Quebec, 1998-2009

Disclosure:

S. Jean,
None;

P. Gamache,
None;

M. Hudson,
None;

L. Bessette,
None;

P. R. Fortin,
None;

G. Boire,
None;

S. Bernatsky,
None.

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