The epidemiology of herpes zoster in patients with invasive cancer

Abstract

9562 Background: Given the limited available data, the aim of this study was to estimate the incidence of Herpes Zoster (HZ) in cancer patients. Methods: In this retrospective cohort study, we used the Kaiser Permanente Northern California cancer registry to identify adult health plan members diagnosed with an invasive hematologic malignancy (HM) or solid tumor malignancy (STM) during 2001–2005. Potential episodes of HZ were ascertained from time of cancer diagnosis through 2006 from electronic databases using inpatient and outpatient diagnoses, laboratory tests, and prescriptions for antivirals. HZ diagnoses were confirmed by abstraction and clinical review of information from patients' inpatient and outpatient medical records. Incidence rates were calculated as the number of new occurrences of HZ per person-time of follow-up. Age-standardized incidence ratios (SIRs) were computed to compare HZ rates in cancer patients to reported rates in the general population (Yawn et al, 2007). Results: Among the 4,728 STM patients (mean age 66 years, range 18–102), the rate of HZ was 12/1000 person years (py) of follow-up (total 9170 py). Among the 1504 HM patients (mean age 67 years, range 18–97), the rate of HZ was 33/1000 py (total 2355 py). The SIRs and 95% confidence intervals for STM and HM were 1.7 (1.4–2.1) and 4.5 (3.5–5.6), respectively. Among patients with HM, incidence rates were highest in the first year after cancer diagnosis (40/1000 py); rates did not appear to vary markedly over time among patients with STM. For either cancer type, HZ rates were similar for males and females and did not increase consistently with increasing age. Conclusions: Compared to the general population, the incidence of HZ was nearly 2 times higher in patients with STM and over 4 times higher in patients with HM. HZ rates did not differ markedly by age or gender. [Table: see text]