Association Between the Initiation of Anti–Tumor Necrosis Factor Therapy and the Risk of Herpes Zoster

Abstract

Herpes zoster reactivation disproportionately affects patients with rheumatoid arthritis (RA). It is unclear whether anti-tumor necrosis factor (anti-TNF) therapy elevates herpes zoster risk. To ascertain whether initiation of anti-TNF therapy compared with nonbiologic comparators is associated with increased herpes zoster risk. We identified new users of anti-TNF therapy among cohorts of patients with RA, inflammatory bowel disease, and psoriasis, psoriatic arthritis, or ankylosing spondylitis from 1998 through 2007 within a large US multi-institutional collaboration combining data from Kaiser Permanente Northern California, Pharmaceutical Assistance Contract for the Elderly, Tennessee Medicaid, and national Medicaid/Medicare programs. We compared herpes zoster incidence between new anti-TNF users (n=33,324) and patients initiating nonbiologic disease-modifying antirheumatic drugs (DMARDs) (n=25,742) within each inflammatory disease cohort (last participant follow-up December 31, 2007). Within these cohorts, we used Cox regression models to compare propensity score-adjusted herpes zoster incidence between new anti-TNF and nonbiologic DMARD users while controlling for baseline corticosteroid use. Incidence of herpes zoster cases occurring after initiation of new anti-TNF or nonbiologic DMARD therapy. Among 33,324 new users of anti-TNF therapy, we identified 310 herpes zoster cases. Crude incidence rates among anti-TNF users were 12.1 per 1000 patient-years (95% CI, 10.7-13.6) for RA, 11.3 per 1000 patient-years (95% CI, 7.7-16.7) for inflammatory bowel disease, and 4.4 per 1000 patient-years (95% CI, 2.8-7.0) for psoriasis, psoriatic arthritis, or ankylosing spondylitis. Baseline use of corticosteroids of 10 mg/d or greater among all disease indications was associated with elevated risk (adjusted hazard ratio [HR], 2.13 [95% CI, 1.64-2.75]) compared with no baseline use. For patients with RA, adjusted incidence rates were similar between anti-TNF and nonbiologic DMARD initiators (adjusted HR, 1.00 [95% CI, 0.77-1.29]) and comparable between all 3 anti-TNF therapies studied. Across all disease indications, the adjusted HR was 1.09 (95% CI, 0.88-1.36). Among patients with RA and other inflammatory diseases, those who initiated anti-TNF therapies were not at higher risk of herpes zoster compared with patients who initiated nonbiologic treatment regimens.