Rheumatoid arthritis, its treatments, and the risk of tuberculosis in Quebec, Canada.
OBJECTIVE
To determine the risk of tuberculosis (TB) among a cohort of patients with rheumatoid arthritis (RA) in Quebec and assess whether this risk is associated with exposure to nonbiologic disease-modifying antirheumatic drugs (DMARDs).


METHODS
We studied a cohort of patients with RA identified from the Quebec provincial physician billing and hospitalization databases for 1980-2003. TB incidence rates were determined for the period 1992-2003 and compared with the general population, standardized for age and sex using the standardized incidence ratio (SIR). Conditional logistic regression was used in a nested case-control analysis to estimate the rate ratio (RR) of TB related to nonbiologic DMARD exposure during the year before the index date.


RESULTS
Of the 24,282 patients with RA in the cohort, 50 cases of TB were identified. The standardized incidence rate was 45.8 cases per 100,000 person-years compared with 4.2 cases per 100,000 person-years in the general population of Quebec (SIR 10.9, 95% confidence interval [95% CI] 7.9-15.0). The adjusted RR of TB was 2.4 (95% CI 1.1-5.4) with corticosteroid use and 3.0 (95% CI 1.6-5.8) with nonbiologic DMARD use.


CONCLUSIONS
The age- and sex-standardized incidence rate of TB in RA patients is 10 times that of the general population. At least some of this risk may be related to nonbiologic DMARD and corticosteroid therapies. Our data support the role of TB screening before initiation of any immunosuppressive therapy.
Brassard
Paul
P
Division of Clinical Epidemiology, McGill University Health Center, Montreal, Quebec, Canada. paul.brassard@clinepi.mcgill.ca
Lowe
Anne-Marie
AM
Bernatsky
Sasha
S
Kezouh
Abbas
A
Suissa
Samy
S
D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012306:Risk; D014376:Tuberculosis / Q000453:epidemiology*
D018501:Antirheumatic Agents; D007166:Immunosuppressive Agents