title: The risk of hospitalized infection in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To determine whether patients with rheumatoid arthritis (RA) are at increased risk of hospitalized infection and whether the risk varies by RA treatment.
  
  
  METHODS
  A retrospective cohort study was conducted using data from a medical and pharmacy claims managed-care database from 1999 to 2006. A total of 24,530 patients were included in the RA cohort; a random sample of non-RA patients served as a comparison cohort (n = 500,000). Rates of hospitalized infection were compared between the cohorts. A nested case-control analysis was performed within the RA cohort to assess the effect of current RA medication use on hospitalized infection risk.
  
  
  RESULTS
  A total of 1,993 patients with RA and 11,977 non-RA patients experienced a hospitalized infection. The rate of first hospitalized infection was higher in the RA cohort [adjusted hazard ratio = 2.03; 95% confidence interval (CI) 1.93-2.13]. In the case-control analysis, the current use of biological disease modifying antirheumatic drugs (DMARD) was associated with slightly increased risk of hospitalized infection [rate ratio (RR) = 1.21; 95% CI 1.02-1.43]. Methotrexate and hydroxychloroquine were associated with decreased risk. Oral corticosteroid use increased risk (RR = 1.92; 95% CI 1.67-2.21), and there was a dose-related effect [< or = 5 mg/day: RR = 1.32 (95% CI 1.06-1.63), 6-10 mg/day: RR = 1.94 (95% CI 1.53-2.46), > 10 mg/day: RR = 2.98 (95% CI 2.41-3.69)].
  
  
  CONCLUSIONS
  These data confirm that individuals with RA are at increased risk of hospitalized infection compared to those without RA. Oral corticosteroid use was associated with a dose-related increase. Biological DMARD use was associated with slightly elevated risk; however, this may reflect confounding and channeling bias.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
authors.forename: Allison L
authors.initials: AL
authors.lastname: Smitten
authors.forename: Hyon K
authors.initials: HK
authors.lastname: Choi
authors.forename: Marc C
authors.initials: MC
authors.lastname: Hochberg
authors.forename: Samy
authors.initials: S
authors.lastname: Suissa
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Simon
authors.forename: Marcia A
authors.initials: MA
authors.lastname: Testa
authors.forename: K Arnold
authors.initials: KA
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000009:adverse effects*; D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects*; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000188:drug therapy*; D016022:Case-Control Studies; D015331:Cohort Studies; D003428:Cross Infection / Q000209:etiology* / Q000276:immunology; D016208:Databases, Factual; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012306:Risk
chemical_list: D000305:Adrenal Cortex Hormones; D018501:Antirheumatic Agents