title: Use of nonbiologic disease-modifying antirheumatic drugs and risk of infection in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  Rheumatoid arthritis (RA) is associated with increased frequency of and mortality from infections, which may be related to host factors, RA itself, inflammation, or medication side effects. This study was undertaken to determine the effect of nonbiologic disease-modifying antirheumatic drugs (DMARDs) on infection risk in RA.
  
  
  METHODS
  We performed a retrospective, longitudinal study of a population-based RA cohort in British Columbia, Canada, followed from January 1996 to March 2003 using administrative data. We evaluated mild infections (requiring a physician visit or antibiotics) and serious infections (requiring or complicating hospitalization). Adjusted risk of mild and serious infections associated with DMARD exposure was estimated using generalized estimating equation extension of multivariate Poisson regression models, after adjusting for baseline covariates (age, sex, RA duration, socioeconomic status) and time-dependent covariates (corticosteroids, comorbidity, prior infections).
  
  
  RESULTS
  A total of 27,710 individuals with RA provided 162,710 person-years of followup. Of these, 25,608 (92%) had at least 1 mild infection and 4,941 (18%) had at least 1 serious infection. Use of DMARDs without corticosteroids was associated with a small decrease in mild infection risk of statistical significance but unclear clinical significance (adjusted rate ratio [RR] 0.90, 95% confidence interval [95% CI] 0.88-0.93 relative to no corticosteroid or DMARD use). Use of DMARDs without corticosteroids was not associated with increased serious infection risk (adjusted RR 0.92, 95% CI 0.85-1.0). Use of corticosteroids increased the risk of mild and serious infections.
  
  
  CONCLUSIONS
  Our results indicate that use of nonbiologic DMARDs, including methotrexate, does not increase the risk of infection in RA, whereas use of corticosteroids does. This has important implications for counseling individuals with RA concerning risks and benefits of DMARDs.
authors.affiliation: University of British Columbia and Arthritis Research Centre of Canada, 895 West 10th Avenue, Vancouver, BC, Canada. dlacaille@arthritisresearch.ca
authors.forename: Diane
authors.initials: D
authors.lastname: Lacaille
authors.forename: Daphne P
authors.initials: DP
authors.lastname: Guh
authors.forename: Michal
authors.initials: M
authors.lastname: Abrahamowicz
authors.forename: Aslam H
authors.initials: AH
authors.lastname: Anis
authors.forename: John M
authors.initials: JM
authors.lastname: Esdaile
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000008:administration & dosage* / Q000009:adverse effects*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000453:epidemiology*; D001955:British Columbia / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007239:Infections / Q000188:drug therapy / Q000453:epidemiology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D000900:Anti-Bacterial Agents; D018501:Antirheumatic Agents