The frequency and consequences of varicella exposure and varicella infection in children receiving maintenance therapy for acute lymphoblastic leukemia

Purpose: The frequency and cost of varicella and varicella exposure were determined in children receiving maintenance chemotherapy for acute lymphocytic leukemia, and the cost of a preventative strategy using the varicella vaccine was estimated. Patients and Methods: Retrospective analysis of clinic and hospital records for 472 children at 12 sites who were receiving maintenance chemotherapy on Protocol 105 of the Childrens Cancer Group. Results: During a mean maintenance period of 21/2 years there were 120 exposures to varicella among susceptible children (10/100 patient-years). During the same period there were 60 cases of varicella (4.6/100 patient-years). Half of the cases of varicella occurred without a known exposure. Exposures and varicella resulted in significant omission or delay in chemotherapy. Total medical charges for varicella-related events were $492,000 ($470 per varicella exposure; $7,450 per case of varicella). A proposed preventative strategy using varicella vaccine after 6 months of maintenance therapy would theoretically reduce varicella-related charges by 80%. Conclusions: Varicella exposure and varicella are common in this patient population. The use of varicella vaccine during the early maintenance period should be considered to prevent these events. This strategy is likely to be safe, and will save significant medical charges, drug omission, disease-related morbidity, hospitalization, and work and school disruption.