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Systematic review highlights high risk of bias of clinical prediction models for blood transfusion in patients undergoing elective surgery
Dhiman P, Ma J, Gibbs VN, Rampotas A, Kamal H, Arshad SS, Kirtley S, Doree C, Murphy MF, Collins GS, et al
Journal of clinical epidemiology. 2023
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Abstract
BACKGROUND Blood transfusion can be a lifesaving intervention after perioperative blood loss. Many prediction models have been developed to identify patients most likely to require blood transfusion during elective surgery, but it is unclear whether any are suitable for clinical practice. STUDY DESIGN AND SETTING We conducted a systematic review, searching MEDLINE, Embase, PubMed, The Cochrane Library, Transfusion Evidence Library, Scopus, and Web of Science databases for studies reporting the development or validation of a blood transfusion prediction model in elective surgery patients between 01/01/2000 to 30/06/2021. We extracted study characteristics, discrimination performance (c-statistics) of final models and data which we used to perform risk of bias assessment using the Prediction model Risk Of Bias ASsessment Tool (PROBAST). RESULTS We reviewed 66 studies (72 developed and 48 externally validated models). Pooled c-statistics of externally validated models ranged from 0.67 to 0.78. Most developed and validated models were at high risk of bias due to handling of predictors, validation methods, and too small sample sizes. CONCLUSION Most blood transfusion prediction models are at high risk of bias and suffer from poor reporting and methodological quality, which must be addressed before they can be safely used in clinical practice.
PICO Summary
Population
Patients undergoing elective surgery (66 studies).
Intervention
Blood transfusion prediction models used perioperatively.
Comparison
Outcome
This systematic review appraised 120 prediction models developed or validated for predicting blood transfusion in elective surgery (72 developed and 48 externally validated models). Pooled c-statistics of externally validated models ranged from 0.67 to 0.78. Most developed and validated models were at high risk of bias due to handling of predictors, validation methods, and too small sample sizes.
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Restrictive versus liberal red blood cell transfusion strategies for people with haematological malignancies treated with intensive chemotherapy or radiotherapy, or both, with or without haematopoietic stem cell support
Estcourt LJ, Malouf R, Trivella M, Fergusson DA, Hopewell S, Murphy MF
The Cochrane Database of Systematic Reviews. 2017;((1)):CD011305.
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Abstract
BACKGROUND Many people diagnosed with haematological malignancies experience anaemia, and red blood cell (RBC) transfusion plays an essential supportive role in their management. Different strategies have been developed for RBC transfusions. A restrictive transfusion strategy seeks to maintain a lower haemoglobin level (usually between 70 g/L to 90 g/L) with a trigger for transfusion when the haemoglobin drops below 70 g/L), whereas a liberal transfusion strategy aims to maintain a higher haemoglobin (usually between 100 g/L to 120 g/L, with a threshold for transfusion when haemoglobin drops below 100 g/L). In people undergoing surgery or who have been admitted to intensive care a restrictive transfusion strategy has been shown to be safe and in some cases safer than a liberal transfusion strategy. However, it is not known whether it is safe in people with haematological malignancies. OBJECTIVES To determine the efficacy and safety of restrictive versus liberal RBC transfusion strategies for people diagnosed with haematological malignancies treated with intensive chemotherapy or radiotherapy, or both, with or without a haematopoietic stem cell transplant (HSCT). SEARCH METHODS We searched for randomised controlled trials (RCTs) and non-randomised trials (NRS) in MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1982), Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 6), and 10 other databases (including four trial registries) to 15 June 2016. We also searched grey literature and contacted experts in transfusion for additional trials. There was no restriction on language, date or publication status. SELECTION CRITERIA We included RCTs and prospective NRS that evaluated a restrictive compared with a liberal RBC transfusion strategy in children or adults with malignant haematological disorders or undergoing HSCT. DATA COLLECTION AND ANALYSIS We used the standard methodological procedures expected by Cochrane. MAIN RESULTS We identified six studies eligible for inclusion in this review; five RCTs and one NRS. Three completed RCTs (156 participants), one completed NRS (84 participants), and two ongoing RCTs. We identified one additional RCT awaiting classification. The completed studies were conducted between 1997 and 2015 and had a mean follow-up from 31 days to 2 years. One study included children receiving a HSCT (six participants), the other three studies only included adults: 218 participants with acute leukaemia receiving chemotherapy, and 16 with a haematological malignancy receiving a HSCT. The restrictive strategies varied from 70 g/L to 90 g/L. The liberal strategies also varied from 80 g/L to 120 g/L.Based on the GRADE rating methodology the overall quality of the included studies was very low to low across different outcomes. None of the included studies were free from bias for all 'Risk of bias' domains. One of the three RCTs was discontinued early for safety concerns after recruiting only six children, all three participants in the liberal group developed veno-occlusive disease (VOD). Evidence from RCTsA restrictive RBC transfusion policy may make little or no difference to: the number of participants who died within 100 days (two trials, 95 participants (RR: 0.25, 95% CI 0.02 to 2.69, low-quality evidence); the number of participants who experienced any bleeding (two studies, 149 participants; RR:0.93, 95% CI 0.73 to 1.18, low-quality evidence), or clinically significant bleeding (two studies, 149 participants, RR: 1.03, 95% CI 0.75 to 1.43, low-quality evidence); the number of participants who required RBC transfusions (three trials; 155 participants: RR: 0.97, 95% CI 0.90 to 1.05, low-quality evidence); or the length of hospital stay (restrictive median 35.5 days (interquartile range (IQR): 31.2 to 43.8); liberal 36 days (IQR: 29.2 to 44), low-quality evidence).We are uncertain whether the restrictive RBC transfusion strategy: decreases quality of life (one trial, 89 participants, fatigue score: restrictive median 4.8 (IQR 4 to 5.2); liberal m
PICO Summary
Population
Children or adults with malignant haematological disorders treated with intensive chemotherapy or radiotherapy, or both, with or without a haematopoietic stem cell transplant (6 studies).
Intervention
Restrictive red blood cell (RBC) transfusion strategy.
Comparison
Liberal RBC transfusion strategy.
Outcome
Evidence from randomised controlled trials showed that a restrictive RBC transfusion policy may make little or no difference to: the number of participants who died within 100 days (RR: 0.25); the number of participants who experienced any bleeding (RR: 0.93), or clinically significant bleeding (RR: 1.03); the number of participants who required RBC transfusions (RR: 0.97); or the length of hospital stay. It was uncertain whether the restrictive RBC transfusion strategy: decreases quality of life, or reduces the risk of developing any serious infection (RR: 1.23).
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Is fresh frozen plasma clinically effective? A systematic review of randomized controlled trials
Stanworth SJ, Brunskill SJ, Hyde CJ, McClelland DL, Murphy MF
British Journal of Haematology. 2004;126((1):):139-152.
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Abstract
Summary: Randomized controlled trials of good quality are a recognized means to robustly assess the efficacy of interventions in clinical practice. A systematic identification and appraisal of all randomized trials involving fresh frozen plasma (FFP) has been undertaken in parallel to the drafting of the updated British Committee for Standards in Haematology guidelines on the use of FFP. A total of 57 trials met the criteria for inclusion in the review. Most clinical uses of FFP, currently recommended by practice guidelines, are not supported by evidence from randomized trials. In particular, there is little evidence for the effectiveness of the prophylactic use of FFP. Many published trials on the use of FFP have enrolled small numbers of patients, and provided inadequate information on the ability of the trial to detect meaningful differences in outcomes between the two patient groups. Other concerns about the design of the trials include the dose of FFP used, and the potential for bias. No studies have taken adequate account of the extent to which adverse effects might negate the clinical benefits of treatment with FFP. There is a need to consider how best to develop new trials to determine the efficacy of FFP in different clinical scenarios to provide the evidence base to support national guidelines for transfusion practice. Trials of modified FFP (e.g. pathogen inactivated) are of questionable value when there is little evidence that the standard product is an effective treatment.
PICO Summary
Population
Patients enrolled in randomised controlled trials (RCTs) for different types of fresh frozen plasma (FFP) usage, (57 RCTs).
Intervention
Fresh frozen plasma.
Comparison
Various comparators, including: no FFP/plasma; a non-blood product; a different blood product; different formulations of FFP.
Outcome
Most clinical uses of FFP, recommended by practice guidelines, were not supported by evidence from randomized trials. In particular, there was little evidence for the effectiveness of the prophylactic use of FFP. Many published trials on the use of FFP enrolled small numbers of patients, and provided inadequate information on the ability of the trial to detect meaningful differences in outcomes between the two patient groups. Other concerns about the design of the trials included the dose of FFP used, and the potential for bias. No studies took adequate account of the extent to which adverse effects might negate the clinical benefits of treatment with FFP.