Abstract
Purpose:
This study investigated the incidence of HZO in patients presenting to MEEI from 2007 until 2013 to define current trends in disease incidence across age groups.
Methods:
A total of 1,283 potential cases were identified by searching the MEEI electronic medical record for patient charts with ICD-9 codes for Herpes zoster, shingles, and varicella from 2007 to 2013. The cases were reviewed to confirm diagnosis of acute HZO, requiring documentation of a skin rash or pain in the V1 or V2 distribution, resulting in 913 patients. The data were analyzed to determine the number of cases of HZO per year as well as stratified by age group. The mean age of HZO patients each year was determined, with a comparision of the 2007 mean age to the 2013 mean age completed by a t test. The number of HZO patients with an immunodeficiency state (including HIV, leukemia, organ transplant, and steroid use) were also analyzed.
Results:
The incidence of HZO at MEEI increased from 71 cases in 2007 to 195 cases in 2013. The mean age of patients with acute HZO reduced significantly from 61.2 years in 2007 to 55.8 years in 2013 (P=0.0168). When subdivided by age, a non-statistically significant trend of decreasing number of patients aged 75-84 years and aged 85-94 years was found. The number of patients aged 35-44 years and aged 55-64 years trended up over time but was not statistically significant. Finally, the number of patients with acute HZO and an immunodeficiency state did not change over the study.
Conclusions:
The research demonstrated an increased incidence of HZO with a reduction in mean age that may be explained by several factors. An increased awareness of Herpes zoster could increase the number of patients presenting to MEEI, but this factor is unlikely to be the sole cause for increased incidence as awareness stems from high disease burden. A greater prevalence of immunodeficiency conditions is a plausible factor, but the current data demonstrates no increase in the number of HZO patients with immunodeficiency. The contribution of vaccination against zoster in reducing mean age of HZO patients is apt to be minimal as only 14.4% of eligible patients received the vaccination by 2010. The remaining factor of pediatric varicella vaccination reducing population exposure and limiting immunologic boost remains a possible explanation for both the increased imcidence in HZO as well as the reduction in mean age.