Background Herpes zoster (HZ) infection occurs more commonly in patients with underlying autoimmune disease, partially due to immunosuppressive treatment. However, little is known about the incidence of HZ in patients with ankylosing spondylitis (AS), especially who were treated with conventional disease modifying anti-rheumatic drugs (cDMARDs) or TNF inhibitors.
Objectives The aims of our study were to investigate the incidence of HZ in AS patients and to determine whether use of cDMARDs or TNF inhibitors could increase the risk of HZ infection in AS patients.
Methods We used database of the Korean National Health Insurance Service–Cohort Sample (1,025,340 individuals) from 2002 to 2013, which was age-, gender-, district- and income stratified random sample. We evaluated HZ incidence among three groups (non-DMARD users, cDMARDs [sulfasalazine, methotrexate] users and TNF inhibitor users) based on drug exposure episodes. Cox proportional hazard analysis was performed to investigate the association between treatment group and HZ infection.
Results Among 1,079 patients with AS, we identified 54 HZ infections. Crude incidence rates were 11.0 per 1000 patient-years (95% CI, 8.2–14.3) in all AS patients; 9.1 (95% CI, 6.2–12.8) in non-DMARD users, 16.7 (95% CI, 9.1–28.0) in cDMARDs users and 14.1 (95% CI, 6.1–27.8) in TNF inhibitor users, respectively. Adjusted hazard ratio (HR) of HZ infection was higher in cDMARDs users and TNF inhibitor users than in non-DMARD users (Table). In subgroup analysis, TNF inhibitor increased the risk of HZ infection more significantly in female (adjusted HR =8.01; 95% CI, 1.97–32.54) and patients older than 50-yr (adjusted HR =7.29; 95% CI, 1.88–28.21), but not in patients exposed to baseline corticosteroid (95% CI, 0.53–32.84) compared to non-DMARD users.
Conclusions The incidence of HZ in AS patients was 11.0 per 1000 patient-years which is similar to the previously reported incidence in general Korean population. cDMARDs or TNF inhibitors increased the risk of HZ infection in AS patients, especially in female and older patients, which can be considered as target of HZ vaccination in AS population.
Disclosure of Interest None declared