Herpes zoster in chronic lymphocytic leukemia: Effect of vaccination and treatment

7527 Background: Patients with Chronic Lymphocytic Leukemia (CLL) are susceptible to infections due to impaired humoral immunity as a complication of the disease, treatments received and age at diagnosis. Herpes zoster (HZ) is a painful, vesicular rash from reactivation of varicella-zoster virus that is common in immunocompromised patients. While HZ vaccines can reduce both varicella-zoster reactivation and post-herpetic neuralgia, vaccination rates are low. The aim of this study is to determine the effect of vaccination on rates of HZ infection in patients with CLL. Methods: We identified patients diagnosed with CLL between September 1999 and October 2015 using Veterans Administration Central Cancer Registry (VACCR). Pharmacy records were used to identify patients who received treatment for CLL and HZ. HZ events were defined as patients with International Classification of Diseases 9th Revision (ICD-9) codes for HZ infection (053) or prescriptions of acyclovir or valacyclovir at a dose of 1500 mg/day or higher or famciclovir at a dose of 1000 mg/day or higher without a diagnosis of Herpes simplex or Bell’s palsy, or an ICD-9 code and prescription above. Cox proportional hazards regression model was used to assess the association between vaccination as a time-varying exposure and developing HZ while controlling age at CLL diagnosis, co-morbidity score, and receipt of first and second line chemotherapy. The study was approved by the St. Louis VA Medical Center institutional review board. Results: A cohort of 7155 patients with CLL was identified using VACCR. 2640 patients (36.9%) and 1161 patients (16.2%) received first and second line chemotherapy respectively. Mean age at first chemotherapy was 69.5 years. We detected 1115 cases of HZ (15.6%) using ICD-9 codes, prescriptions or both. 615 patients (8.6%) received HZ vaccinations. Patients with HZ were younger (mean 68.0 vs. 69.8 years, p < 0.001), had similar co-morbidities, and were more likely to get treatment for CLL (58.1% vs. 33.0%, p < 0.001). Using a time-varying analysis, there was a trend for HZ vaccine to decrease the risk of developing HZ (HR 0.71, 95% CI 0.49-1.04, p = 0.082). When adjusting for age and co-morbidity, patients with CLL treated with first line chemotherapy had a higher risk of HZ (HR 2.34, 95% CI 2.02-2.71, p < 0.001) compared to those never receiving therapy. Second line chemotherapy increased risk of HZ (HR 1.32, 95% CI 1.13-1.55, p < 0.001) beyond first line treatment. Conclusions: HZ is prevalent in patients with CLL and affects younger patients who require chemotherapy. The risk of developing HZ increases in recipients of first and second line chemotherapy. In the time-varying analysis, there was a trend towards decreased infection in patients who received HZ vaccination. Further studies in a more modern cohort that assess infection risk using a larger vaccinated group with the newer and more effective HZ vaccine are warranted.