Incidence of herpes zoster and associated events including stroke—a population-based cohort study

Karin Sundström, Caroline E. Weibull, Karin Söderberg-Löfdal, Tomas Bergström, Pär Sparén, Lisen Arnheim-Dahlström

More detailed understanding of herpes zoster (HZ) is called for in the context of an increasing observed frequency of disease, and ongoing discussions regarding potential consequences of the disease. Thus, population-based data on incidence and complications of HZ are needed. We conducted a register-based cohort study in Västra Götaland County (population 1.5 million) in Sweden. We collected data on all patients diagnosed with HZ during the years 2008 to 2010 from population-based registers. Incidence rates (IR) of HZ and related complications were calculated and stratified by age and sex. There were 13 269 new HZ cases during the study period. Overall, the IR of herpes zoster in both genders was 3.25 (95 % CI: 3.16-3.34) per 1000 person years in 2010. The incidence was consistently higher in women than in men and in older than in young. A history of immunosuppression was more common than in the general population. The incidence was highest in individuals over 80 years of age (IR 9.2 per 1000 person years, 95 % CI: 8.8-9.6) during 2008-2010. The most common complications to HZ were ocular engagement and postherpetic neuralgia; risks for stroke and sepsis were significantly elevated during the one year following diagnosis, especially in the youngest age group of patients 0-39 years. Herpes zoster is more common in women, the elderly and immunosuppressed individuals. We verify a population-based association between herpes zoster and risk for stroke and sepsis, which may merit concern.