Incidence of Herpes Zoster in Patients With Rheumatoid Arthritis in the United States: A Retrospective Cohort Study.

Abstract

To estimate the incidence of herpes zoster (HZ) in patients with rheumatoid arthritis (RA) compared with the general population in the USA. This retrospective, longitudinal cohort study used data from an administrative claims database containing both commercial and Medicare Advantage Part D data, with a data period from October 2015 to February 2020. Patients were aged ≥ 18 years and divided into 2 cohorts: patients with RA and patients without RA. Diagnosis and procedure codes were used to identify HZ cases and calculate incidence rates (IRs) of HZ in the 2 cohorts. Data were stratified by age group (ie, 18-49, 18-29, 30-39, 40-49, 50-64, and ≥ 65 yrs) and RA therapy type. IR ratios (IRRs), adjusted by cohort baseline characteristics, were estimated using generalized linear models to compare the incidence of HZ between cohorts. The overall IR of HZ was higher in the RA cohort (21.5 per 1000 person-years [PY]; N = 67,650) than in the non-RA cohort (7.6 per 1000 PY; N = 11,401,743). The highest IRs in both cohorts were observed in the age group of ≥ 65 yrs (23.4 and 11.4 per 1000 PY in the RA cohort and non-RA cohort, respectively). The overall adjusted IRR of HZ was 1.93 (95% CI 1.87-1.99, P < 0.001) for the RA cohort compared with the non-RA cohort. In the RA cohort, the highest IRs by medication class were observed in patients using corticosteroids and those using Janus kinase inhibitors. These results highlight the increased incidence of HZ in patients with RA.