Current trends in clinical studies of allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is a specialized intervention performed at select centers worldwide. The extent to which specific aspects of care in allogeneic HSCT have been studied and the types of studies performed for different aspects of care remains incompletely documented. Studies in allogeneic HSCT were systematically identified from selected high-profile transplant journals between July 2010 and June 2011 and previously reported in a study addressing the definition of clinical outcomes in HSCT. All articles were retrieved and assessed for study characteristics and categorized by specific aspects of care related to allogeneic HSCT. One hundred sixteen articles were retrieved and reviewed in detail by 2 investigators. The most studied aspect of care was conditioning regimens. Transfusion practices were the most understudied aspect of care. Interestingly, most studies included both adult and pediatric patients. Studies involving all hematological malignancies were encountered more often than disease-specific studies. Geographically, most patients described in the published reports were treated only in North America or only in Europe. Most studies were retrospective (78), and 25 reported on multicenter registry data. Of the 38 prospective studies, 8 were randomized controlled trials (RCTs) and predominantly focused on prevention and treatment of graft-versus-host disease (GVHD) and infections. Median follow-up was longer in retrospective registry studies (54 months) and shortest in RCTs (32 months). The proportion of positive outcomes in retrospective and prospective studies was remarkably high (>80% for all categories) and not significantly different across all aspects of care (P > .05). When comparing RCTs and registry data studies, this proportion was similar and high (95% and 100%, respectively, P > .05). Our study highlights the established and important role of retrospective registry studies for many aspects of care and suggests RCTs may be most relevant for studies on infectious complications and GVHD.