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.