Decline in hospitalization rates for herpes zoster in Italy (2003-2018): reduction in the burden of disease or changing of hospitalization criteria?

Abstract

Herpes Zoster (HZ) is a very demanding disease caused by the reactivation of latent Varicella Zoster Virus. The main aim of this study was to estimate the burden of the HZ hospitalizations in Italy from 2003 to 2018 evaluating temporal trends. Retrospective population-based study analyzing Hospital Discharge Records. Hospitalization records reporting the ICD-9 CM 053.X code in the principal diagnosis or in any of the five secondary diagnoses were considered as cases. Trends of hospitalization rates have been evaluated by Joinpoint analyses. Overall, 99,036 patients were hospitalized with HZ in the 16-year period of the study, and 83,720 (84.5%) of these patients were over 50years. Hospitalization rate was 10.4 per 100,000 persons/year with a significant decreasing trend from 13.9 in 2003-2006 to 7.8 in 2015-2018 (p < 0.001). Hospitalization rates showed a 20-fold higher risk among subjects aged over 80years and 11-fold higher risk among 70-79-year-old subjects with respect to those aged less than 50years. Over time, a statistically significant increase was observed for the case fatality rate (from 1.2 to 1.7%; p < 0.001) and the median length of stay (from 7 to 8days; p < 0.001). Zoster is a disease that causes hospitalization as relatively frequent complication and the observed reduced trend over time could be due to a restriction in hospitalization criteria instead of a reduced burden of disease. The decreasing trend should be carefully interpreted, since it could have an impact on promoting herpes zoster vaccination.