The risk of herpes zoster in patients with ankylosing spondylitis: Analysis of the Korean National Health Insurance Service – Sample cohort database

OBJECTIVES: The aims of our study were to determine whether the use of conventional disease-modifying antirheumatic drugs (cDMARDs) or tumor necrosis factor α (TNFα) inhibitors increase the risk of herpes zoster (HZ) in patients with ankylosing spondylitis (AS). METHODS: We searched the South Korean National Health Insurance Service - National Sample Cohort Database for relevant patient records between 2002 and 2013. We evaluated the incidence of HZ by categorizing patients into in three treatment groups: disease-modifying antirheumatic drug (DMARD) nonusers, cDMARD users and TNFα inhibitor users. RESULTS: Incidence rates of HZ was 11.0 per 1000 person-years in patients with AS. The adjusted hazard ratio of HZ was higher in cDMARD and TNFα inhibitor users than in DMARD nonusers. In subgroup analyses, current treatment with a TNFα inhibitor increased the risk of HZ significantly both in female patients and in patients aged 50 years or older, but not in patients taking steroids, compared to DMARD nonusers. CONCLUSIONS: Treatment with either TNFα inhibitors or cDMARDs is associated with a higher risk of HZ, especially in female patients and older patients, and these two patient groups could therefore benefit from HZ vaccination.