Methodologic quality assessment of red blood cell transfusion guidelines and the evidence base of more restrictive transfusion thresholds

BACKGROUND: Recent literature suggests that more restrictive red blood cell (RBC) transfusion practices are equivalent or better than more liberal transfusion practices. The methodologic quality of guidelines recommending more restrictive transfusion thresholds and their underlying scientific evidence is unclear. Therefore, we aimed to evaluate the quality of the development process of RBC transfusion guidelines and to investigate the underlying evidence of guidelines recommending a more restrictive hemoglobin (Hb) threshold. STUDY DESIGN AND METHODS: Via systematic literature screening of relevant databases (NGC, GIN, Medline, and Embase), RBC transfusion guidelines recommending a more restrictive Hb level (<6, <7, or