Healthcare utilization and costs among patients with herpes zoster and solid tumor malignancy on chemotherapy: A retrospective cohort study

Immunosuppressed patients with solid tumor malignancies (STMs) are particularly vulnerable to herpes zoster (HZ). This study estimated the incidence of HZ and evaluated healthcare resource utilization and costs for persons with STM receiving chemotherapy with and without incident HZ. We conducted a retrospective claims study of adults with STM receiving chemotherapy between January 1, 2010 and June 30, 2014. Patients were followed from their first chemotherapy date through development of HZ, health plan disenrollment, the study end date, or 24 months. HZ incidence was calculated and stratified by patient characteristics. Adjusted HZ incidence was estimated using Poisson regression. Healthcare resource utilization and costs were compared between patients with HZ (cases) and propensity score–matched controls without HZ during a variable follow-up period. Adjusted healthcare costs were estimated using Lin regression to control for informative censoring. Of 155,480 patients with STM receiving chemotherapy, 3100 (2.0%) developed HZ, yielding an adjusted HZ incidence rate of 13.8/1000 person-years (PY). HZ cases (n = 3004) had significantly higher healthcare resource utilization than matched controls (n = 15,020). Adjusted annual costs were $48,077 for cases vs $41,645 for matched controls, corresponding to a differential cost of $6432 annually. After adjustment for potential confounders, patients with STM receiving chemotherapy had an HZ incidence of 13.8/1000 PY; those who developed HZ used more healthcare resources and incurred higher costs than those who did not. These findings suggest that HZ prevention by vaccination could improve outcomes and reduce costs in this population.