TNF-α antagonist use and risk of hospitalization for infection in a national cohort of veterans with rheumatoid arthritis

Medications used to treat rheumatoid arthritis (RA) may confer an increased risk of infection. We conducted a retrospective cohort study of veterans with RA followed in the United States Department of Veterans Affairs health care system from October 1998 through September 2005. Risk of hospitalization for infection associated with tumor necrosis factor (TNF)-α antagonists therapy was measured using an extension of Cox proportional hazards regression, adjusting for demographic characteristics, comorbid illnesses, and other medications used to treat RA.A total of 20,814 patients met inclusion criteria, including 3796 patients who received infliximab, etanercept, or adalimumab. Among the study cohort, 1465 patients (7.0%) were hospitalized at least once for infection. There were 1889 hospitalizations for infection. The most common hospitalized infections were pneumonia, bronchitis, and cellulitis. Age and several comorbid medical conditions were associated with hospitalization for infection. Prednisone (hazard ratio [HR], 2.14; 95% confidence interval [CI], 1.88-2.43) and TNF-α antagonist use (HR, 1.24; 95% CI, 1.02-1.50) were associated with hospitalization for infection, while the use of disease-modifying antirheumatic drugs (DMARDs) other than TNF-α antagonists was not. Compared to etanercept, infliximab was associated with risk for hospitalization for infection (HR, 1.51; 95% CI, 1.14-2.00), while adalimumab use was not (HR, 0.95; 95% CI, 0.68-1.33). In all treatment groups, rate of hospitalization for infection was highest in the first 8 months of therapy.We conclude that patients with RA who are treated with TNF-α antagonists are at higher risk for hospitalization for infection than those treated with other DMARDs. Prednisone use is also a risk factor for hospitalization for infection.