Background: Autologous Hematopoietic Stem Cell Transplant (aHCT) is used to treat cancers. Conditioning regimens cause immunosuppression increasing risk for herpes zoster (HZ). Incidence of HZ among aHCT patients is 100-200/1,000 PY compared to 3-5/1,000 PY in the general population. HZ may increase healthcare resource utilization (HRU) and cost; antiviral prophylaxis (AP) can mitigate risk of HZ. However, real world data are lacking on AP use, HZ risk, HRU and cost in aHCT patients.
Methods: Claims were analyzed for patients in the Optum Research and Impact National Benchmark Databases. Adults aged ≥18 years with an aHCT procedure between 1/200612/2011 were included; those with HZ pre-aHCT or received Zostavax during the study period, or had <12 months of enrollment were excluded. HZ incidence was calculated as cases observed after aHCT over accrued time-at-risk in person-years (PY). AP use and duration were defined by prescription fills. HRU and all-cause costs, HZ onset date was set for HZ cases, and a random date was selected for those w/o HZ; follow-up was required for 365 days. Costs were assessed from 21 days pre-onset date through 364 days post-onset date and compared by t-test and generalized linear model.
Results: There were 223 HZ cases among 2,350 aHCT recipients; HZ incidence was 62.18/1,000 PY (95% CI: 54.28-70.90). The mean time-at-risk was 405 (SD=340) vs. 529 (SD=458) days for those with HZ vs. w/o HZ. Incidence increased with age; females had higher incidence (72 vs 56/1,000 PY, p=0.061). Receiving corticosteroids was associated with a higher risk of HZ (odds ratio [OR]: 1.40, 95% CI: 1.00-1.95). HZ incidence was higher among patients without AP; but even those with AP had incidence 6-fold higher than the immunocompetent population (Figure 1). One-year costs for those with HZ (n=128) vs. w/o HZ (n=591) did not differ significantly in bivariate (($86,515 (SD $101,381) vs. $91,448 (SD $123,785) (p=0.604)), or multivariate analyses (cost ratio: 0.900, 95% CI: 0.683-1.184, p=0.451).
Conclusion: aHCT recipients have high incidence of HZ despite antiviral prophylaxis. Costs incurred among aHCT recipients with HZ were not significantly different from those without HZ but variance was large. Further evaluation of inpatient and outpatient costs is ongoing.
D. Zhang, None
C. Acosta, Merck: Employee and Shareholder , Salary
L. Finelli, None