The risk of hospitalized infection in patients with rheumatoid arthritis

To determine whether patients with rheumatoid arthritis (RA) are at increased risk of hospitalized infection and whether the risk varies by RA treatment.

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.

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)].

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.