To clarify the incidence and the risks of herpes zoster infection in Japanese patients with rheumatoid arthritis (RA).
By using a self-report of occurrence of herpes zoster in patients with RA in a large observational cohort study from 2005 to 2010, the standardized incidence rate was calculated. A Cox model was used to analyze risk factors for occurrence of herpes zoster.
A total of 7,986 patients (female 83.1%) accumulated 30,140 patient-years of observation, and 366 events were confirmed. The standardized incidence rate per 1,000 patient-years was 9.1 (95% confidence interval (CI) 6.2-12.9) in total, 7.8 (3.6-14.8) in men, and 10.3 (6.8-15.0) in women. The risk factors for herpes zoster were age [/10 years: Hazard ratio (HR) 1.268, 95% CI 1.153-1.393, p < 0.0001), high disease activity compared with remission (HR 1.642, 95% CI 1.067-2.528, p < 0.05), prednisolone (< 5 mg/day compared with 0 mg/day: HR 1.531, 95% CI 1.211-1.936, p < 0.001; ≥ 5 mg/day compared with 0 mg/day: HR 1.471, 95% CI 1.034-2.093, p < 0.05), and methotrexate (HR 1.382, 95% CI 1.076-1.774, p < 0.05).
This study quantified the historical incidence and risk for herpes zoster in Japanese RA patients, and is a benchmark for future studies.