2.2 Review and research
2.2.1 Systematic review process
Systematic reviews were undertaken to attempt to answer the question specific to medical transfusion, and the generic questions relevant to all six modules. The systematic review questions are listed in Box 2.1.
To answer these questions, comprehensive search strategies were designed, as detailed in Volume 2 of the technical report. Searches were conducted in relevant electronic databases, bibliographies of studies identified as relevant, and literature recommended by expert members of the CRG. The search terms did not specifically search for or limit retrieval of articles to studies that addressed socioeconomic, Aboriginal or Torres Strait Islander subgroups. However, the reviewers were required to isolate any papers addressing these populations for specific consideration by the CRG. No papers were identified that addressed these populations specifically.
The systematic review included only data from studies that met the relevant inclusion criteria, were of adequate quality, and were published between 1966 and July 2010. Identification of relevant evidence and assessment of evidence was conducted in accordance with NHMRC standards and procedures for externally developed guidelines.13
The question ‘What is the effect of recombinant activated factor VII (rFVIIa) (prophylaxis or treatment) on morbidity, mortality and transfusion rate?’ was not included in this review, but was covered (as Question 6) in the document Patient Blood Management Guidelines: Module 1 – Critical Bleeding/ Massive Transfusion.4
Box 2.1 Systematic review questions
Questions 1 – 5 are relevant to all six modules of these guidelines; Question 6 is specific to medical transfusion (i.e. to this module).
- Question 1 – In medical patients, is anaemia an independent risk factor for adverse outcomes? (Aetiological question)
- Question 2 – In medical patients, what is the effect of RBC transfusion on patient outcomes? (Interventional question)
- Question 3 – In medical patients, what is the effect of non-transfusion interventions to increase Hb concentration on morbidity, mortality and need for RBC blood transfusion? (Interventional question)
- Question 4 – In medical patients, what is the effect of FFP, cryoprecipitate, fibrinogen concentrate, and/or platelet transfusion on patient outcomes? (Interventional question)
- Question 5 – In medical patients, at what INR (PT/APTT) for FFP, fibrinogen level for cryoprecipitate and platelet count for platelets concentrates should patients be transfused to avoid risks of significant adverse events? (Interventional and Prognostic question)
- Question 6 – In specific regularly and chronically transfused patients, at what Hb threshold should patients be transfused to avoid adverse outcomes? (Interventional question)
APTT, activated partial thromboplastin time; FFP, fresh frozen plasma; Hb, haemoglobin; INR, international normalised ratio; PT, prothrombin time; RBC, red blood cell
2.2.2 Background material
Material relevant to background questions was gathered by fellows or registrars under the supervision of CRG members. Sources included medical textbooks, grey literature, published scientific and review articles, series yearbooks and other relevant medical literature; however, systematic review processes were not applied. The questions researched are listed in Box 2.2.Box 2.2 Background research questions
- Background question 1 – In patients with malignancies (solid tumours) undergoing radiotherapy, do interventions (transfusion or ESAs) aimed at raising the Hb concentration during radiotherapy affect patient outcomes (e.g. response rate, tumour recurrence or tumour-free survival)?
- Background question 2 – When should a patient be retested after a transfusion to assess the response, guide if further transfusions are required and avoid over-transfusion?
ESA, erythropoiesis-stimulating agent; Hb, haemoglobin