Incidence of herpes zoster in Japanese patients with rheumatoid arthritis from 2005 to 2010.

OBJECTIVE

To clarify the incidence and the risks of herpes zoster infection in Japanese patients with rheumatoid arthritis (RA).

METHODS

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.

RESULTS

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).

CONCLUSION

This study quantified the historical incidence and risk for herpes zoster in Japanese RA patients, and is a benchmark for future studies.