Risk of herpes zoster among patients with psychiatric diseases: A population-based study

Background Psychiatric disorders have been shown to be associated with impaired immune response, including decreased cellular immunity to varicella-zoster virus. However, the risk of herpes zoster (HZ) in psychiatric patients is, to date, unknown. Objective The aim of this study was to determine the risk of herpes zoster (HZ) in psychiatric patients compared with the general population. Methods We used data from the Taiwan Longitudinal Health Insurance Database from 2004 to 2006. Our study cohort consisted of patients aged 18 years and older diagnosed with psychiatric disorders in 2004 (N = 42 340). The comparison cohort (N = 169 360) consisted of four age- and gender-matched controls randomly selected for every patient in the study cohort. All subjects were followed from the date of cohort entry until they developed HZ or the end of 2006, whichever was earliest. Stratified Cox proportional hazard regressions were performed to compute the 2-year HZ-free survival rates. Results After adjusting for potential confounders, we found patients with psychiatric disorders were more likely to have an episode of HZ than the control population [adjusted hazard ratio (HR), 1.29; 95% confidence interval (CI), 1.18-1.38]. When stratified by age and psychiatric diagnostic categories, in patients aged â60 years, the adjusted HRs for HZ were 1.34 (P = 0.026) for patients with affective psychoses, 1.42 (P <0.001) for those with neurotic illness or personality disorders and 1.53 (P <0.001) for patients with other mental disorders. However, in patients aged >60 years, only neurotic illness or personality disorders were significantly associated with an increased risk of HZ (adjusted HR, 1.26; P = 0.003). Conclusions Our analysis suggests that patients with psychiatric disorders are at increased risk of HZ, especially those aged a≤60 years. Further study is required to elucidate the nature of this association.