Chronic lymphocytic leukemia (CLL) patients have higher risks of infection for a range of reasons. Among these factors is the painful, vesicular rash known as herpes zoster (HZ).
In light of higher rates of HZ infection associated with impaired humoral immunity as a complication of CLL, adverse effects of treatments received and age at diagnosis, a study presented at the recent American Society of Clinical Oncology annual meeting looked at preventive use of HZ vaccines.
“While HZ vaccines can reduce both varicella-zoster reactivation and post-herpetic neuralgia, vaccination rates are low,” write the authors from the Saint Louis Veterans Affairs Medical Center, Saint Louis University Hospital and colleagues.
The study team sought to determine the effect of vaccination on rates of HZ infection in patients with CLL. To do that, they identified patients diagnosed with CLL between September 1999 and October 2015 from the Veterans Administration Central Cancer Registry (VACCR) and collected pharmacy records to identify patients who received treatment for CLL and HZ.
Included as having had an HZ event were any patients with an International Classification of Diseases 9th Revision (ICD-9) codes for HZ infection (053) or prescriptions of acyclovir or valacyclovir at a dosage of 1,500 mg/day or higher or famciclovir at a dosage of 1,000 mg/day or higher without a diagnosis of herpes simplex or Bell’s palsy.
Participants included 7,155 patients with CLL identified via VACCR; 2,640 patients (36.9%) received first-line chemotherapy, whereas 1,161 patients received second-line chemotherapy. Mean age at first chemotherapy was 69.5 years.
Researchers identified 1,115 cases of HZ (15.6%) using ICD-9 codes, prescriptions or both, and 615 patients (8.6%) who had received HZ vaccinations. The study notes that HZ patients tended to be younger, with a mean age of 68.0 versus 69.8 years (P <.001), had similar comorbidities and were more likely to get treatment for CLL (58.1% vs. 33.0%; P <.001).
The authors noted a trend for HZ vaccine to decrease the risk of developing HZ (hazard ratio [HR] 0.71, 95% CI 0.49-1.04; P = .082). At the same time, after adjustment for age and comorbidity, they also found that patients with CLL treated with first-line chemotherapy had a higher risk of HZ (HR 2.34, 95% CI 2.02-2.71; P <.001) compared with those never receiving chemotherapy. Second-line chemotherapy further increased the risk of HZ (HR 1.32, 95% CI 1.13-1.55; P <.001) beyond first-line treatment.
“HZ is prevalent in patients with CLL and affects younger patients who require chemotherapy,” the researchers concluded. “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.”
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