The risk of herpes zoster in patients with rheumatoid arthritis in the United States and the United Kingdom

Objective. To determine whether the incidence of herpes zoster is elevated in patients with rheumatoid arthritis (RA) and whether herpes zoster is associated with use of disease-modifying antirheumatic drugs (DMARDs) in patients with RA. Methods. Two retrospective cohort studies were conducted using data from a US integrated managed care database (PharMetrics claims database) from 1998-2002 and the UK General Practice Research Database (GPRD) between 1990-2001. Rates of herpes zoster among patients with RA and randomly sampled non-RA patients were compared. A nested case-control analysis was performed within each RA cohort to examine the effect of current treatment on herpes zoster risk. Results. A total of 122,272 patients with RA from the PharMetrics database and 38,621 from the GPRD were included. The adjusted hazard ratios of herpes zoster for patients with RA compared with non-RA patients were 1.91 (95% confidence interval [95% CI] 1.80-2.03) in the PharMetrics database and 1.65 (95% CI 1.57-1.75) in the GPRD. In the PharMetrics database, current use of biologic DMARDs alone was associated with herpes zoster (odds ratio [OR] 1.54, 95% CI 1.04-2.29), as was current use of traditional DMARDs alone (OR 1.37, 95% CI 1.18-1.59). In the GPRD, current use of traditional DMARDs was associated with herpes zoster (OR 1.27, 95% CI 1.10-1.48). In both data sources, use of oral corticosteroids was associated with herpes zoster regardless of concomitant therapies. Conclusion. Data from 2 large databases suggested that patients with RA are at increased risk of herpes zoster. Among patients with RA, DMARDs and/or use of oral corticosteroids appeared to be associated with herpes zoster.