title: How low should we go: A systematic review and meta-analysis of the impact of restrictive red blood cell transfusion strategies in oncology.
abstract: BACKGROUND
  Most non-oncologic clinical practice guidelines recommend restrictive allogeneic blood transfusion practices; however, there is a lack of consensus regarding the best transfusion practice in oncology. We conducted a systematic review of the literature to compare the efficacy and safety of restrictive versus liberal transfusion strategies in patients with cancer.
  
  
  METHODS
  A literature search using MEDLINE, PUBMED and EMBASE identified all controlled studies comparing the use of restrictive with liberal transfusion in adult oncology participants up to August 10, 2015. Two review authors independently assessed studies for inclusion, extracted data and appraised the quality of the included studies. The primary outcomes of interest were blood utilization and all-cause mortality.
  
  
  RESULTS
  Out of 4241 citations, six studies (3 randomized and 3 non-randomized) involving a total of 983 patients were included in the final review. The clinical context of the studies varied with 3 chemotherapy and 3 surgical studies. The overall risk of bias in all studies was moderate to high. Restrictive transfusion strategies were associated with a 36% reduced risk of receiving a perioperative transfusion (risk ratio (RR) 0.64, 95% confidence interval (CI) 0.49-0.83). There was no difference in mortality between the strategies (RR 1.00, 95% CI 0.32-3.18). There were no differences in adverse events reported between the restrictive and liberal transfusion strategies.
  
  
  CONCLUSIONS
  Restrictive strategy appears to decrease blood utilization without increasing morbidity or mortality in oncology. This review is limited by a paucity of high quality studies on this topic. Better designed studies are warranted.
authors.affiliation: Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. Electronic address: LSPrescott@mdanderson.org.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Prescott
authors.affiliation: Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Jolyn S
authors.initials: JS
authors.lastname: Taylor
authors.affiliation: Department of General Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Lopez-Olivo
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Mark F
authors.initials: MF
authors.lastname: Munsell
authors.affiliation: The University of Texas School of Public Health, Houston, TX 77030, USA.
authors.forename: Helena M
authors.initials: HM
authors.lastname: VonVille
authors.affiliation: The University of Texas School of Public Health, Houston, TX 77030, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Lairson
authors.affiliation: Department of Clinical Education, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Diane C
authors.initials: DC
authors.lastname: Bodurka
mesh_terms: D017707:Erythrocyte Transfusion / Q000009:adverse effects / Q000379:methods* / Q000592:standards*; D006801:Humans; D008495:Medical Oncology / Q000379:methods* / Q000592:standards*; D009369:Neoplasms / Q000628:therapy*; D016032:Randomized Controlled Trials as Topic; D014184:Transplantation, Homologous
keywords: Anemia; Blood; Cancer; Neoplasms; Systematic review; Transfusion