General epidemiological data regarding herpes zoster (HZ) are necessary for treatment and prevention of this disease. In addition, epidemiological data can play an important role in evaluating the efficacy and impact of vaccination. Though several epidemiological studies of HZ in Korea have been conducted, they usually depend on hospital-based data and may not be representative of HZ characteristics all over Korea. The purpose of this study was to evaluate the incidence and other epidemiological features of HZ in the general Korean population. We used population-based medical records from the Health Insurance Review & Assessment Service, which includes 50,908,646 medical insurance subscribers, to calculate the incidence of HZ. Also, we analyzed an age-stratified random sample of 1,375,842 individuals to study descriptive epidemiologic characteristics of HZ in Korea in 2011. We observed that the incidence of HZ was 10.4 per 1,000 person-years and was strongly correlated with age. Sex had a major influence on HZ incidence; overall, there were 12.6 cases per 1,000 person years in women and 8.3 cases per 1,000 person years in men. There was no difference in incidence according to the locality and season.Graphical Abstract

BackgroundHerpes zoster (HZ) is generally thought to occur once in a lifetime and recurrence is considered to be limited to immunocompromised individuals. Although HZ recurrence rates seem to be increasing, there have been few studies exploring these rates in the general population. We investigated the recurrence rate and associated risk factors in the general population.MethodsWe used the population-based samples of the National Health Insurance Service database to identify cases of initial HZ episodes from January 1, 2002 to December 31, 2013. We also followed up on these cases through December 31, 2013 to identify recurrence.ResultsOverall, the incidence rate of HZ is 5.1 per 1,000 person years and the recurrence rate is 12.0 per 1,000 person years. There were 2,100 recurrent cases out of 39,441 initial episodes with 4.4 years of the mean follow-up period. We identified significant risk factors for recurrence such as old age (51–70 years) (hazard ratio [HR], 1.447; 95% confidence interval [CI], 1.311–1.598), women (1.476; 1.345–1.619), zoster-related pain (ZRP) longer than 30 days (cases of ZRP lasting 31–90 days [1.200; 1.042–1.383], and ZRP lasting longer than 90 days [2.293; 1.990–2.643]). Concurrent hematologic malignancies (2.864; 1.929–4.251), autoimmune diseases (1.466; 1.252–1.715), dyslipidemia (1.390; 1.263–1.530), and hypertension (1.222; 1.107–1.350) were also significant risk factors.ConclusionOur results suggest that the recurrence of HZ is much more common than generally expected, and that the associated risk factors can play an important role in predicting recurrence.