Safety and tolerability of oseltamivir prophylaxis in hematopoietic stem cell transplant recipients: A retrospective case-control study

Background. Oseltamivir is safe and effective in immunocompetent persons, and prophylactic use is recommended during influenza outbreaks. However, no data exist regarding the use of oseltamivir as prophylaxis among patients undergoing hematopoietic stem cell transplantation ( HSCT). Methods. In January 2002, an influenza A outbreak was identified when 4 cases occurred within 1 week at an outpatient residential facility for patients undergoing HSCT. Oseltamivir prophylaxis ( 75 mg per day) was initiated for all asymptomatic patients living in the housing facility. Retrospectively, 45 patients ( 25 of whom had undergone HSCT, and 20 of whom were pre-HSCT candidates) who received oseltamivir prophylaxis were evaluated for adverse events. These 45 patients were matched 1: 1 with control subjects who received transplants during the period 1994-2003 and did not receive prophylaxis; they were matched according to donor type, conditioning regimen, cytomegalovirus serostatus, time after HSCT, and recipient age ( +/- 5 years). The frequency of clinical and laboratory adverse events was determined by chart review and graded using National Cancer Institute Common Terminology Criteria. Results. Forty-five residents received oseltamivir for a median of 17 days ( range, 10-81 days). No new cases of influenza A occurred in the facility. Seven weeks after initiation of prophylaxis, 1 resident who had been noncompliant to prophylaxis developed an influenza B infection, followed by an additional case of influenza B that occurred in a patient who had not received prophylaxis. No deaths occurred that were attributable to prophylaxis. The proportions of clinical and laboratory adverse events meeting common terminology criteria grades 2-4 or 3-4 were not significantly different between the case patients who received oseltamivir prophylaxis and control subjects. Conclusion. Oseltamivir prophylaxis appeared to be safe and well tolerated in managing an influenza outbreak in an HSCT outpatient residence.