Design issues in a prospective randomized double-blinded trial of prophylaxis with fluconazole versus voriconazole after allogeneic hematopoietic cell transplantation

Abstract

Background. Aspergillus infections pose the toughest infectious challenges to the clinician caring for hematopoietic cell transplant recipients. About 15% of patients become infected, with a case fatality rate of ∼65%. To date, no effective prophylactic strategies have been developed. Methods. Voriconazole, a recently licensed extended-spectrum azole, with demonstrated efficacy against aspergillus, is currently being tested as a potential prophylactic agent against aspergillus and other invasive fungal infections. Logistic issues - such as patient selection, choice of comparator, blinding of study drugs, duration of study drug administration, and how to handle empirical amphotericin B for possible invasive fungal infections - and analytic concerns, including choice and definition of the primary end point and the potential confounding effect of informative censoring (as a result of noninfectious events), were considered in the design of the clinical trial. Results. The trial is now under way, with a projected 3-year enrollment period. Conclusions. Each design decision shaped the trial in a way that permitted certain questions to be answered while not allowing others to be addressed. Once completed, the trial's results must be interpreted in light of these design details.