Initiation of Tumor Necrosis Factor-alpha Antagonists and the Risk of Hospitalization for Infection in Patients With Autoimmune Diseases

CONTEXT: Although tumor necrosis factor (TNF)-alpha antagonists are increasingly used in place of nonbiologic comparator medications, their safety profile remains incomplete. OBJECTIVES: To determine whether initiation of TNF-alpha antagonists compared with nonbiologic comparators is associated with an increased risk of serious infections requiring hospitalization. DESIGN, SETTING, AND PATIENTS: Within a US multi-institutional collaboration, we assembled retrospective cohorts (1998-2007) of patients with rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and psoriasis, psoriatic arthritis, or ankylosing spondylitis (psoriasis and spondyloarthropathies) combining data from Kaiser Permanente Northern California, New Jersey and Pennsylvania Pharmaceutical Assistance programs, Tennessee Medicaid, and national Medicaid/Medicare. TNF-alpha antagonists and nonbiologic regimens were compared in disease-specific propensity score (PS)-matched cohorts using Cox regression models with nonbiologics as the reference. Baseline glucocorticoid use was evaluated as a separate covariate. MAIN OUTCOME MEASURE: Infections requiring hospitalization (serious infections) during the first 12 months after initiation of TNF-alpha antagonists or nonbiologic regimens. RESULTS: Study cohorts included 10,484 RA, 2323 IBD, and 3215 psoriasis and spondyloarthropathies matched pairs using TNF-alpha antagonists and comparator medications. Overall, we identified 1172 serious infections, most of which (53%) were pneumonia and skin and soft tissue infections. Among patients with RA, serious infection hospitalization rates were 8.16 (TNF-alpha antagonists) and 7.78 (comparator regimens) per 100 person-years (adjusted hazard ratio [aHR], 1.05 [95% CI, 0.91-1.21]). Among patients with IBD, rates were 10.91 (TNF-alpha antagonists) and 9.60 (comparator) per 100 person-years (aHR, 1.10 [95% CI, 0.83-1.46]). Among patients with psoriasis and spondyloarthropathies, rates were 5.41 (TNF-alpha antagonists) and 5.37 (comparator) per 100 person-years (aHR, 1.05 [95% CI, 0.76-1.45]). Among patients with RA, infliximab was associated with a significant increase in serious infections compared with etanercept (aHR, 1.26 [95% CI, 1.07-1.47]) and adalimumab (aHR, 1.23 [95% CI, 1.02-1.48]). Baseline glucocorticoid use was associated with a dose-dependent increase in infections. CONCLUSION: Among patients with autoimmune diseases, compared with treatment with nonbiologic regimens, initiation of TNF-alpha antagonists was not associated with an increased risk of hospitalizations for serious infections.

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