Herpes zoster burden in patients with asthma: real-world incidence, healthcare resource utilisation and cost

Background Herpes zoster (HZ) is a painful condition caused by reactivation of the varicella-zoster virus. The objectives of this study were to compare HZ incidence in adults with asthma versus adults without asthma and to compare healthcare resource use as well as direct costs in adults with HZ and asthma versus adults with asthma alone in the USA.Methods This retrospective longitudinal cohort study included adults aged >= 18 years across the USA. Patients were identified from Optum's deidentified Clinformatics Data Mart Database, an administrative claims database, between 1 October 2015 and 28 February 2020, including commercially insured and Medicare Advantage with part D beneficiaries. Cohorts of patients with and without asthma, and separate cohorts of patients with asthma and HZ and with asthma but not HZ, were identified using International Classification of Diseases 10th Revision, Clinical Modification codes. HZ incidence, healthcare resource use and costs were compared, adjusting for baseline characteristics, between the relevant cohorts using generalised linear models.Results HZ incidence was higher in patients with asthma (11.59 per 1000 person-years) than patients without asthma (7.16 per 1000 person-years). The adjusted incidence rate ratio (aIRR) for HZ in patients with asthma, compared with patients without asthma, was 1.34 (95% CI 1.32 to 1.37). Over 12 months of follow-up, patients with asthma and HZ had more inpatient stays (aIRR 1.11; 95% CI 1.02 to 1.21), emergency department visits (aIRR 1.26; 95% CI 1.18 to 1.34) and outpatient visits (aIRR 1.19; 95% CI 1.16 to 1.22), and direct healthcare costs that were US dollars ($) 3058 (95% CI $1671 to $4492) higher than patients with asthma without HZ.Conclusion Patients with asthma had a higher incidence of HZ than those without asthma, and among patients with asthma HZ added to their healthcare resource use and costs.