High incidence of herpes zoster in nonmyeloablative hematopoietic stem cell transplantation.

Although the use of nonmyeloablative (NMA) hematopoietic stem cell transplantation (HSCT) regimens has expanded in the past decade, little data exist to support antiviral prophylaxis to prevent herpes zoster (HZ) in recipients who are seropositive for varicella-zoster virus in this population. The present study examined the clinical features, incidence, and risk factors for HZ in a homogeneous cohort of NMA allogeneic HSCT recipients. We conducted a retrospective cohort study assessing all patients who underwent sibling NMA HSCT at Maisonneuve-Rosemont Hospital (Montreal) between July 2000 and December 2008. All patients received the same conditioning regimen, immunoprophylaxis, and graft-versus-host disease therapy. The diagnosis of HZ was defined clinically. Factors associated with HZ were identified using a Cox proportional hazards model. A total of 179 patients were followed for a median of 33 months (interquartile range, 21-59). HZ developed in 66 patients (37%) at a median of 8.3 months post-HSCT; the incidence rate was 175 cases/1000 person-years. The estimated cumulative HZ incidence was 27% at 1 year, 36% at 2 years, and 44% at 3 years. Thoracic dermatomes were most frequently involved (30%); dissemination occurred in 5 patients. No deaths resulted from HZ, but 23% of patients developed postherpetic neuralgia. In multivariate analysis, reactivation of cytomegalovirus and herpes simplex virus was associated with a reduced likelihood of HZ (hazard ratio, 0.54 and 0.33, respectively). Antiviral prophylaxis or treatment for cytomegalovirus and herpes simplex virus reactivations were protective against HZ. The incidence of HZ in our cohort of NMA HSCT recipients is similar to the incidence reported in HSCT recipients who received a myeloablative conditioning regimen. Given the observed high risk, we conclude that recommendations for antiviral prophylaxis should apply, at least for the first year, to the NMA HSCT population as well.