Herpes Zoster Risk in Patients with Rheumatoid Arthritis and Its Association with Medications Used.

Rheumatoid arthritis (RA) was associated with the risk of incident herpes zoster (HZ), which might be influenced by medication use by RA patients. We aimed to investigate the association of RA with the risk of incident HZ and how the HZ risk effected by RA medications in CIC RA patients. We conducted an observational study including population-based representative insurance claims data of 19,673 patients with RA and 39,346 matched patients without RA during 1997-2010 from the Taiwan National Health Insurance Research Database; we identified 1651 patients with catastrophic illness-certified (CIC) RA and 11,557 matched patients with non-CIC RA. Exploratory analyses assessed the association between RA/CIC RA and risk of incident HZ and its complications. The association of prescribed medications with HZ risk in CIC RA patients was also estimated. The incidence rates of HZ were higher in CIC RA patients and non-CIC RA than in the matched people without RA (21.95 and 14.03 vs. 7.36 events per 1000 person-years, respectively). The adjusted incidence rate ratio (95% confidence interval (CI)) for HZ was 1.74 (1.65-1.84) in RA patients vs. matched non-RA and 1.65 (1.44-1.89) in CIC RA patients vs. non-CIC RA. For HZ complications, RA had a 2.85-fold higher risk than non-RA, and CIC RA had a 1.78-fold higher risk than non-CIC RA. Moreover, in CIC RA patients, prednisolone use was associated with incident HZ risk compared with prednisolone nonuse (adjusted odds ratio 1.48, 1.08-2.03); prolonged prednisolone use (approximately 5 years) increased the risk (adjusted odds ratio 2.16, 1.46-3.19). Our results suggested that RA was positively associated with HZ risk, particularly in RA patients with prednisolone use.