Epidemiologic assessments of sufficiently large populations are required in order to obtain robust estimates of disease prevalence and incidence, particularly when exploring the influence of various factors (age, sex, calendar time). We undertook this study to describe the epidemiology of rheumatoid arthritis (RA) over the past 15 years.
We used the Ontario Rheumatoid Arthritis administrative Database (ORAD), a validated population-based research database of all Ontarians with RA. The ORAD records were linked with census data to calculate crude and age and sex-standardized prevalence and incidence rates from 1996 to 2010. Vital statistics were used to estimate annual all-cause mortality during the study period.
As of 2010, there were 97,499 Ontarians with RA, corresponding to a cumulative prevalence of 0.9%. Age and sex-standardized RA prevalence increased steadily over time from 473 (95% confidence interval [95% CI] 469-478) per 100,000 population (0.49%) in 1996 to 784 (95% CI 779-789) per 100,000 population (0.9%) in 2010. Age and sex-standardized incidence per 100,000 population ranged from 62 (95% CI 60-63) in 1996 to 54 (95% CI 52-55) in 2010. All-cause mortality decreased by a relative 21.4% since 1996.
Over a 15-year period, we observed an increase in RA prevalence over time. This rise may be attributed to the increasing time to ascertain cases (which may have been latent in the population during earlier years of the study), increasing survival, and/or an increase in the aging background population. Incidence appears to be stable.
To describe patterns of disease-modifying antirheumatic drug (DMARD) use during pregnancy in a population-based cohort, and to evaluate the association between autoimmune disease, DMARDs, corticosteroids, and nonsteroidal antiinflammatory drugs (NSAIDs) and preeclampsia.
Using health care utilization databases from British Columbia (1997-2006), we compared the risk for preeclampsia among 44,786 women with and without autoimmune disease with study drug dispensings before pregnancy (past users) and before and during the first 20 gestational weeks (continuous users). Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated.
Only 414 women (0.1%) had a DMARD dispensing during pregnancy. The incidence of preeclampsia was 2.3% for past DMARD users, 2.7% for past corticosteroid users, and 2.9% for past NSAID users. Compared to past users, the continuous DMARD user RR was 2.29 (95% CI 0.81-6.44), and was 0.89 (95% CI 0.51-1.56) for corticosteroid and 0.84 (95% CI 0.63-1.10) for NSAID users. Compared to women without autoimmune disease, the delivery year-adjusted RR was 2.02 (95% CI 1.11-3.64) for women with systemic lupus erythematosus (SLE). The DMARD results were attenuated when antimalarials were excluded, and the delivery year-adjusted RR was 0.95 (95% CI 0.25-3.55) when the DMARD analysis was restricted to women with autoimmune disease.
Few women were exposed to DMARDs during pregnancy. We observed a 2-fold increased risk of preeclampsia among women with SLE and a nonsignificant increase in risk in DMARD users. The DMARD and preeclampsia association was attenuated when antimalarials were excluded and null when restricted to women with autoimmune disease, which suggests the association is likely due to greater autoimmune disease severity in DMARD users.
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