Incidence of Herpes Zoster in Patients With Rheumatoid Arthritis: Comparison With Controls and Risk According to Different Treatments

OBJECTIVE: To compare the incidence of herpes zoster (HZ) between patients with rheumatoid arthritis (RA) and matched controls from a health plan in Buenos Aires, and to assess incidence under different immunosuppressive treatments. METHODS: Patients with newly diagnosed RA between 2000 and 2023 were matched 1:2 by age and sex with controls. Incidence densities per 100 patient-years (PY) were calculated. Cox regression and Kaplan-Meier analyses were performed to identify factors associated with HZ. RESULTS: A total of 460 RA patients and 920 controls (81.3% women, mean age: 62.2 y) were included, with a median follow-up of 9 years. The RA cohort contributed 4184 PY and controls 9783 PY. Forty-six HZ events occurred in RA and 29 in controls. HZ incidence was 1.08 (95% CI: 0.80-1.47) per 100 PY in RA versus 0.29 (95% CI: 0.19-0.44) in controls [incidence rate ratio (IRR) 3.63; 95% CI: 2.28-5.77; p