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Transfusion thresholds for guiding red blood cell transfusion
Carson JL, Stanworth SJ, Dennis JA, Trivella M, Roubinian N, Fergusson DA, Triulzi D, Dorée C, Hébert PC
The Cochrane database of systematic reviews. 2021;12:Cd002042
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Abstract
BACKGROUND The optimal haemoglobin threshold for use of red blood cell (RBC) transfusions in anaemic patients remains an active field of research. Blood is a scarce resource, and in some countries, transfusions are less safe than in others because of inadequate testing for viral pathogens. If a liberal transfusion policy does not improve clinical outcomes, or if it is equivalent, then adopting a more restrictive approach could be recognised as the standard of care. OBJECTIVES The aim of this review update was to compare 30-day mortality and other clinical outcomes for participants randomised to restrictive versus liberal red blood cell (RBC) transfusion thresholds (triggers) for all clinical conditions. The restrictive transfusion threshold uses a lower haemoglobin concentration as a threshold for transfusion (most commonly, 7.0 g/dL to 8.0 g/dL), and the liberal transfusion threshold uses a higher haemoglobin concentration as a threshold for transfusion (most commonly, 9.0 g/dL to 10.0 g/dL). SEARCH METHODS We identified trials through updated searches: CENTRAL (2020, Issue 11), MEDLINE (1946 to November 2020), Embase (1974 to November 2020), Transfusion Evidence Library (1950 to November 2020), Web of Science Conference Proceedings Citation Index (1990 to November 2020), and trial registries (November 2020). We checked the reference lists of other published reviews and relevant papers to identify additional trials. We were aware of one trial identified in earlier searching that was in the process of being published (in February 2021), and we were able to include it before this review was finalised. SELECTION CRITERIA We included randomised trials of surgical or medical participants that recruited adults or children, or both. We excluded studies that focused on neonates. Eligible trials assigned intervention groups on the basis of different transfusion schedules or thresholds or 'triggers'. These thresholds would be defined by a haemoglobin (Hb) or haematocrit (Hct) concentration below which an RBC transfusion would be administered; the haemoglobin concentration remains the most commonly applied marker of the need for RBC transfusion in clinical practice. We included trials in which investigators had allocated participants to higher thresholds or more liberal transfusion strategies compared to more restrictive ones, which might include no transfusion. As in previous versions of this review, we did not exclude unregistered trials published after 2010 (as per the policy of the Cochrane Injuries Group, 2015), however, we did conduct analyses to consider the differential impact of results of trials for which prospective registration could not be confirmed. DATA COLLECTION AND ANALYSIS We identified trials for inclusion and extracted data using Cochrane methods. We pooled risk ratios of clinical outcomes across trials using a random-effects model. Two review authors independently extracted data and assessed risk of bias. We conducted predefined analyses by clinical subgroups. We defined participants randomly allocated to the lower transfusion threshold as being in the 'restrictive transfusion' group and those randomly allocated to the higher transfusion threshold as being in the 'liberal transfusion' group. MAIN RESULTS A total of 48 trials, involving data from 21,433 participants (at baseline), across a range of clinical contexts (e.g. orthopaedic, cardiac, or vascular surgery; critical care; acute blood loss (including gastrointestinal bleeding); acute coronary syndrome; cancer; leukaemia; haematological malignancies), met the eligibility criteria. The haemoglobin concentration used to define the restrictive transfusion group in most trials (36) was between 7.0 g/dL and 8.0 g/dL. Most trials included only adults; three trials focused on children. The included studies were generally at low risk of bias for key domains including allocation concealment and incomplete outcome data. Restrictive transfusion strategies reduced the risk of receiving at least one RBC transfusion by 41% across a broad range of clinical contexts (risk ratio (RR) 0.59, 95% confidence interval (CI) 0.53 to 0.66; 42 studies, 20,057 participants; high-quality evidence), with a large amount of heterogeneity between trials (I² = 96%). Overall, restrictive transfusion strategies did not increase or decrease the risk of 30-day mortality compared with liberal transfusion strategies (RR 0.99, 95% CI 0.86 to 1.15; 31 studies, 16,729 participants; I² = 30%; moderate-quality evidence) or any of the other outcomes assessed (i.e. cardiac events (low-quality evidence), myocardial infarction, stroke, thromboembolism (all high-quality evidence)). High-quality evidence shows that the liberal transfusion threshold did not affect the risk of infection (pneumonia, wound infection, or bacteraemia). Transfusion-specific reactions are uncommon and were inconsistently reported within trials. We noted less certainty in the strength of evidence to support the safety of restrictive transfusion thresholds for the following predefined clinical subgroups: myocardial infarction, vascular surgery, haematological malignancies, and chronic bone-marrow disorders. AUTHORS' CONCLUSIONS Transfusion at a restrictive haemoglobin concentration decreased the proportion of people exposed to RBC transfusion by 41% across a broad range of clinical contexts. Across all trials, no evidence suggests that a restrictive transfusion strategy impacted 30-day mortality, mortality at other time points, or morbidity (i.e. cardiac events, myocardial infarction, stroke, pneumonia, thromboembolism, infection) compared with a liberal transfusion strategy. Despite including 17 more randomised trials (and 8846 participants), data remain insufficient to inform the safety of transfusion policies in important and selected clinical contexts, such as myocardial infarction, chronic cardiovascular disease, neurological injury or traumatic brain injury, stroke, thrombocytopenia, and cancer or haematological malignancies, including chronic bone marrow failure. Further work is needed to improve our understanding of outcomes other than mortality. Most trials compared only two separate thresholds for haemoglobin concentration, which may not identify the actual optimal threshold for transfusion in a particular patient. Haemoglobin concentration may not be the most informative marker of the need for transfusion in individual patients with different degrees of physiological adaptation to anaemia. Notwithstanding these issues, overall findings provide good evidence that transfusions with allogeneic RBCs can be avoided in most patients with haemoglobin thresholds between the range of 7.0 g/dL and 8.0 g/dL. Some patient subgroups might benefit from RBCs to maintain higher haemoglobin concentrations; research efforts should focus on these clinical contexts.
PICO Summary
Population
Adults and children across a range of clinical contexts including surgery (48 studies, n= 21,433).
Intervention
Restrictive red blood cell (RBC) transfusion threshold strategy.
Comparison
Liberal RBC transfusion threshold strategy.
Outcome
Restrictive transfusion strategies reduced the risk of receiving at least one RBC transfusion by 41% across a broad range of clinical contexts (risk ratio (RR) 0.59, 95% confidence interval (CI) 0.53 to 0.66; 42 studies, 20,057 participants; high-quality evidence), with a large amount of heterogeneity between trials (I² = 96%). Overall, restrictive transfusion strategies did not increase or decrease the risk of 30-day mortality compared with liberal transfusion strategies (RR 0.99, 95% CI 0.86 to 1.15; 31 studies, 16,729 participants; I² = 30%; moderate-quality evidence) or any of the other outcomes assessed (i.e. cardiac events (low-quality evidence), myocardial infarction, stroke, thromboembolism (all high-quality evidence)). High-quality evidence showed that the liberal transfusion threshold did not affect the risk of infection (pneumonia, wound infection, or bacteraemia). Transfusion-specific reactions were uncommon and were inconsistently reported within trials.
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Interventions for preventing silent cerebral infarcts in people with sickle cell disease
Estcourt LJ, Kimber C, Hopewell S, Trivella M, Doree C, Abboud MR
Cochrane Database Syst Rev. 2020;4:Cd012389
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BACKGROUND Sickle cell disease (SCD) is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. SCD can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Silent cerebral infarcts are the commonest neurological complication in children and probably adults with SCD. Silent cerebral infarcts also affect academic performance, increase cognitive deficits and may lower intelligence quotient. OBJECTIVES To assess the effectiveness of interventions to reduce or prevent silent cerebral infarcts in people with SCD. SEARCH METHODS We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 14 November 2019. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register: 07 October 2019. SELECTION CRITERIA Randomised controlled trials comparing interventions to prevent silent cerebral infarcts in people with SCD. There were no restrictions by outcomes examined, language or publication status. DATA COLLECTION AND ANALYSIS We used standard Cochrane methodological procedures. MAIN RESULTS We included five trials (660 children or adolescents) published between 1998 and 2016. Four of the five trials were terminated early. The vast majority of participants had the haemoglobin (Hb)SS form of SCD. One trial focused on preventing silent cerebral infarcts or stroke; three trials were for primary stroke prevention and one trial dealt with secondary stroke prevention. Three trials compared the use of regular long-term red blood cell transfusions to standard care. Two of these trials included children with no previous long-term transfusions: one in children with normal transcranial doppler (TCD) velocities; and one in children with abnormal TCD velocities. The third trial included children and adolescents on long-term transfusion. Two trials compared the drug hydroxyurea and phlebotomy to long-term transfusions and iron chelation therapy: one in primary prevention (children), and one in secondary prevention (children and adolescents). The quality of the evidence was moderate to very low across different outcomes according to GRADE methodology. This was due to trials being at high risk of bias because they were unblinded; indirectness (available evidence was only for children with HbSS); and imprecise outcome estimates. Long-term red blood cell transfusions versus standard care Children with no previous long-term transfusions and higher risk of stroke (abnormal TCD velocities or previous history of silent cerebral infarcts) Long-term red blood cell transfusions may reduce the incidence of silent cerebral infarcts in children with abnormal TCD velocities, risk ratio (RR) 0.11 (95% confidence interval (CI) 0.02 to 0.86) (one trial, 124 participants, low-quality evidence); but make little or no difference to the incidence of silent cerebral infarcts in children with previous silent cerebral infarcts on magnetic resonance imaging and normal or conditional TCDs, RR 0.70 (95% CI 0.23 to 2.13) (one trial, 196 participants, low-quality evidence). No deaths were reported in either trial. Long-term red blood cell transfusions may reduce the incidence of: acute chest syndrome, RR 0.24 (95% CI 0.12 to 0.49) (two trials, 326 participants, low-quality evidence); and painful crisis, RR 0.63 (95% CI 0.42 to 0.95) (two trials, 326 participants, low-quality evidence); and probably reduces the incidence of clinical stroke, RR 0.12 (95% CI 0.03 to 0.49) (two trials, 326 participants, moderate-quality evidence). Long-term red blood cell transfusions may improve quality of life in children with previous silent cerebral infarcts (difference estimate -0.54; 95% confidence interval -0.92 to -0.17; one trial; 166 participants), but may have no effect on cognitive function (least squares means: 1.7, 95% CI -1.1 to 4.4) (one trial, 166 participants, low-quality evidence). Transfusions continued versus transfusions halted: children and adolescents with normalised TCD velocities (79 participants; one trial) Continuing red blood cell transfusions may reduce the incidence of silent cerebral infarcts, RR 0.29 (95% CI 0.09 to 0.97 (low-quality evidence). We are very uncertain whether continuing red blood cell transfusions has any effect on all-cause mortality, Peto odds ratio (OR) 8.00 (95% CI 0.16 to 404.12); or clinical stroke, RR 0.22 (95% CI 0.01 to 4.35) (very low-quality evidence). The trial did not report: comparative numbers for SCD-related adverse events; quality of life; or cognitive function. Hydroxyurea and phlebotomy versus transfusions and chelation Primary prevention, children (121 participants; one trial) We are very uncertain whether switching to hydroxyurea and phlebotomy has any effect on: silent cerebral infarcts (no infarcts); all-cause mortality (no deaths); risk of stroke (no strokes); or SCD-related complications, RR 1.52 (95% CI 0.58 to 4.02) (very low-quality evidence). Secondary prevention, children and adolescents with a history of stroke (133 participants; one trial) We are very uncertain whether switching to hydroxyurea and phlebotomy has any effect on: silent cerebral infarcts, Peto OR 7.28 (95% CI 0.14 to 366.91); all-cause mortality, Peto OR 1.02 (95%CI 0.06 to 16.41); or clinical stroke, RR 14.78 (95% CI 0.86 to 253.66) (very low-quality evidence). Switching to hydroxyurea and phlebotomy may increase the risk of SCD-related complications, RR 3.10 (95% CI 1.42 to 6.75) (low-quality evidence). Neither trial reported on quality of life or cognitive function. AUTHORS' CONCLUSIONS We identified no trials for preventing silent cerebral infarcts in adults, or in children who do not have HbSS SCD. Long-term red blood cell transfusions may reduce the incidence of silent cerebral infarcts in children with abnormal TCD velocities, but may have little or no effect on children with normal TCD velocities. In children who are at higher risk of stroke and have not had previous long-term transfusions, long-term red blood cell transfusions probably reduce the risk of stroke, and other SCD-related complications (acute chest syndrome and painful crises). In children and adolescents at high risk of stroke whose TCD velocities have normalised, continuing red blood cell transfusions may reduce the risk of silent cerebral infarcts. No treatment duration threshold has been established for stopping transfusions. Switching to hydroxyurea with phlebotomy may increase the risk of silent cerebral infarcts and SCD-related serious adverse events in secondary stroke prevention. All other evidence in this review is of very low-quality.
PICO Summary
Population
Children or adolescents with sickle cell disease (SCD), five trials (n=660).
Intervention
Long-term red blood cell transfusions.
Comparison
Standard care or halting transfusions, or hydroxyurea and phlebotomy.
Outcome
Long-term red blood cell transfusions may reduce the incidence of silent cerebral infarcts in children with abnormal transcranial doppler (TCD) velocities; but make little or no difference to the incidence of silent cerebral infarcts in children with previous silent cerebral infarcts on magnetic resonance imaging and normal or conditional TCDs. Long-term red blood cell transfusions may improve quality of life in children with previous silent cerebral infarcts, but may have no effect on cognitive function. Continuing red blood cell transfusions may reduce the incidence of silent cerebral infarcts. It is uncertain whether switching to hydroxyurea and phlebotomy has any effect on silent cerebral infarcts (no infarcts); all-cause mortality (no deaths); risk of stroke (no strokes); or SCD-related complications. For children and adolescents with a history of stroke it was uncertain whether switching to hydroxyurea and phlebotomy has any effect on silent cerebral infarcts all-cause mortality or clinical stroke. Switching to hydroxyurea and phlebotomy may increase the risk of SCD-related complications.
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3.
Preoperative blood transfusions for sickle cell disease
Estcourt LJ, Kimber C, Trivella M, Doree C, Hopewell S
Cochrane Database Syst Rev. 2020;7:Cd003149
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BACKGROUND Sickle cell disease (SCD) is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. SCD can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Surgical interventions are more common in people with SCD, and occur at much younger ages than in the general population. Blood transfusions are frequently used prior to surgery and several regimens are used but there is no consensus over the best method or the necessity of transfusion in specific surgical cases. This is an update of a Cochrane Review. OBJECTIVES To determine whether there is evidence that preoperative blood transfusion in people with SCD undergoing elective or emergency surgery reduces mortality and perioperative or sickle cell-related serious adverse events. To compare the effectiveness of different transfusion regimens (aggressive or conservative) if preoperative transfusions are indicated in people with SCD. SEARCH METHODS We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 28 January 2020 We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register: 19 September 2019. SELECTION CRITERIA All randomised controlled trials and quasi-randomised controlled trials comparing preoperative blood transfusion regimens to different regimens or no transfusion in people with SCD undergoing elective or emergency surgery. There was no restriction by outcomes examined, language or publication status. DATA COLLECTION AND ANALYSIS Two authors independently assessed trial eligibility and the risk of bias and extracted data. MAIN RESULTS Three trials with 990 participants were eligible for inclusion in the review. There were no ongoing trials identified. These trials were conducted between 1988 and 2011. The majority of people included had haemoglobin (Hb) SS SCD. The majority of surgical procedures were considered low or intermediate risk for developing sickle cell-related complications. Aggressive versus simple red blood cell transfusions One trial (551 participants) compared an aggressive transfusion regimen (decreasing sickle haemoglobin to less than 30%) to a simple transfusion regimen (increasing haemoglobin to 100 g/L). This trial re-randomised\ participants and therefore quantitative analysis was only possible on two subsets of data: participants undergoing cholecystectomy (230 participants); and participants undergoing tonsillectomy or adenoidectomy surgeries (107 participants). Data were not combined as we do not know if any participant received both surgeries. Overall, the quality of the evidence was very low across different outcomes according to GRADE methodology. This was due to the trial being at high risk of bias primarily due to lack of blinding, indirectness and the outcome estimates being imprecise. Cholecystectomy subgroup results are reported in the abstract. Results for both subgroups were similar. There was no difference in all-cause mortality between people receiving aggressive transfusions and those receiving conservative transfusions. No deaths occurred in either subgroup. There were no differences between the aggressive transfusion group and conservative transfusion group in the number of people developing: * an acute chest syndrome, risk ratio (RR) 0.84 (95% confidence interval (CI) 0.38 to 1.84) (one trial, 230 participants, very low-quality evidence); * vaso-occlusive crisis, risk ratio 0.30 (95% CI 0.09 to 1.04) (one trial, 230 participants, very low quality evidence); * serious infection, risk ratio 1.75 (95% CI 0.59 to 5.18) (one trial, 230 participants, very low-quality evidence); * any perioperative complications, RR 0.75 (95% CI 0.36 to 1.55) (one trial, 230 participants, very low-quality evidence); * a transfusion-related complication, RR 1.85 (95% CI 0.89 to 3.88) (one trial, 230 participants, very low-quality evidence). Preoperative transfusion versus no preoperative transfusion Two trials (434 participants) compared a preoperative transfusion plus standard care to a group receiving standard care. Overall, the quality of the evidence was low to very low across different outcomes according to GRADE methodology. This was due to the trials being at high risk of bias due to lack of blinding, and outcome estimates being imprecise. One trial was stopped early because more people in the no transfusion arm developed an acute chest syndrome. There was no difference in all-cause mortality between people receiving preoperative transfusions and those receiving no preoperative transfusions (two trials, 434 participants, no deaths occurred). There was significant heterogeneity between the two trials in the number of people developing an acute chest syndrome, a meta-analysis was therefore not performed. One trial showed a reduced number of people developing acute chest syndrome between people receiving preoperative transfusions and those receiving no preoperative transfusions, risk ratio 0.11 (95% confidence interval 0.01 to 0.80) (65 participants), whereas the other trial did not, RR 4.81 (95% CI 0.23 to 99.61) (369 participants). There were no differences between the preoperative transfusion groups and the groups without preoperative transfusion in the number of people developing: * a vaso-occlusive crisis, Peto odds ratio (OR) 1.91 (95% confidence interval 0.61 to 6.04) (two trials, 434 participants, very low-quality evidence). * a serious infection, Peto OR 1.29 (95% CI 0.29 to 5.71) (two trials, 434 participants, very low-quality evidence); * any perioperative complications, RR 0.24 (95% CI 0.03 to 2.05) (one trial, 65 participants, low-quality evidence). There was an increase in the number of people developing circulatory overload in those receiving preoperative transfusions compared to those not receiving preoperative transfusions in one of the two trials, and no events were seen in the other trial (no meta-analysis performed). AUTHORS' CONCLUSIONS There is insufficient evidence from randomised trials to determine whether conservative preoperative blood transfusion is as effective as aggressive preoperative blood transfusion in preventing sickle-related or surgery-related complications in people with HbSS disease. There is very low quality evidence that preoperative blood transfusion may prevent development of acute chest syndrome. Due to lack of evidence this review cannot comment on management for people with HbSC or HbSbeta(+) disease or for those with high baseline haemoglobin concentrations.
PICO Summary
Population
Patients with sickle cell disease (SCD) undergoing elective or emergency surgery (3 studies, n= 990).
Intervention
Aggressive transfusion regime prior to surgery.
Comparison
Conservative transfusion regime or no transfusion prior to surgery.
Outcome
There was no difference between the aggressive and the conservative transfusion regimens before surgery in preventing surgical or sickle‐related complications immediately after surgery. There was no difference in all‐cause mortality between patients receiving preoperative transfusions and those receiving no preoperative transfusions. There was significant heterogeneity between the two trials in the number of people developing an acute chest syndrome, however there was no difference between giving a blood transfusion before surgery compared to not giving a blood transfusion before surgery in preventing any other sickle‐related or surgical complications immediately after surgery.
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4.
Regular long-term red blood cell transfusions for managing chronic chest complications in sickle cell disease
Estcourt LJ, Hopewell S, Trivella M, Hambleton IR, Cho G
The Cochrane database of systematic reviews. 2019;2019(10)
Abstract
BACKGROUND Sickle cell disease is a genetic haemoglobin disorder, which can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Sickle cell disease is one of the most common severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. The two most common chronic chest complications due to sickle cell disease are pulmonary hypertension and chronic sickle lung disease. These complications can lead to morbidity (such as reduced exercise tolerance) and increased mortality. This is an update of a Cochrane Review first published in 2011 and updated in 2014 and 2016. OBJECTIVES We wanted to determine whether trials involving people with sickle cell disease that compare regular long-term blood transfusion regimens with standard care, hydroxycarbamide (hydroxyurea) any other drug treatment show differences in the following: mortality associated with chronic chest complications; severity of established chronic chest complications; development and progression of chronic chest complications; serious adverse events. SEARCH METHODS We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. Date of the last search: 19 September 2019. We also searched for randomised controlled trials in the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, Issue 10, 14 November 2018), MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1937), the Transfusion Evidence Library (from 1950), and ongoing trial databases to 14 November 2018. SELECTION CRITERIA We included randomised controlled trials of people of any age with one of four common sickle cell disease genotypes, i.e. Hb SS, Sbeta masculine, SC, or Sbeta(+) that compared regular red blood cell transfusion regimens (either simple or exchange transfusions) to hydroxycarbamide, any other drug treatment, or to standard care that were aimed at reducing the development or progression of chronic chest complications (chronic sickle lung and pulmonary hypertension). DATA COLLECTION AND ANALYSIS We used the standard methodological procedures expected by Cochrane. MAIN RESULTS No studies matching the selection criteria were found. AUTHORS' CONCLUSIONS There is a need for randomised controlled trials looking at the role of long-term transfusion therapy in pulmonary hypertension and chronic sickle lung disease. Due to the chronic nature of the conditions, such trials should aim to use a combination of objective and subjective measures to assess participants repeatedly before and after the intervention.
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5.
Transfusion of red blood cells stored for shorter versus longer duration for all conditions
Shah A, Brunskill SJ, Desborough MJ, Doree C, Trivella M, Stanworth SJ
The Cochrane Database of Systematic Reviews. 2018;12:CD010801.
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BACKGROUND Red blood cell (RBC) transfusion is a common treatment for anaemia in many conditions. The safety and efficacy of transfusing RBC units that have been stored for different durations before a transfusion is a current concern. The duration of storage for a RBC unit can be up to 42 days. If evidence from randomised controlled trials (RCT) were to indicate that clinical outcomes are affected by storage duration, the implications for inventory management and clinical practice would be significant. OBJECTIVES To assess the effects of using red blood cells (RBCs) stored for a shorter versus a longer duration, or versus RBCs stored for standard practice duration, in people requiring a RBC transfusion. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PubMed (for epublications), LILACS, Transfusion Evidence Library, Web of Science CPCI-S and four international clinical trial registries on 20 November 2017. SELECTION CRITERIA We included RCTs that compared transfusion of RBCs of shorter versus longer storage duration, or versus standard practice storage duration. DATA COLLECTION AND ANALYSIS We used standard Cochrane methods. MAIN RESULTS We included 22 trials (42,835 participants) in this review.The GRADE quality of evidence ranged from very low to moderate for our primary outcome of in-hospital and short-term mortality reported at different time points.Transfusion of RBCs of shorter versus longer storage duration Eleven trials (2249 participants) compared transfusion of RBCs of shorter versus longer storage duration. Two trials enrolled low birth weight neonates, two enrolled children with severe anaemia secondary to malaria or sickle cell disease, and eight enrolled adults across a range of clinical settings (intensive care, cardiac surgery, major elective surgery, hospitalised in-patients, haematology outpatients). We judged only two trials to be at low risk of bias across all domains; most trials had an unclear risk for multiple domains.Transfusion of RBCs of shorter versus longer storage duration probably leads to little or no difference in mortality at seven-day follow-up (risk ratio (RR) 1.42, 95% confidence interval (CI) 0.66 to 3.06; 1 trial, 3098 participants; moderate quality evidence) or 30-day follow-up (RR 0.85, 95%CI 0.50 to 1.45; 2 trials, 1121 participants; moderate quality evidence) in adults undergoing major elective cardiac or non-cardiac surgery.For neonates, no studies reported on the primary outcome of in-hospital or short-term mortality. At 40 weeks gestational age, the effect of RBCs of shorter versus longer storage duration on the risk of death was uncertain, as the quality of evidence is very low (RR 0.90, 95% CI 0.41 to 1.85; 1 trial, 52 participants).The effect of RBCs of shorter versus longer storage duration on the risk of death in children with severe anaemia was also uncertain within 24 hours of transfusion (RR 1.50, 95% CI 0.43 to 5.25; 2 trials, 364 participants; very low quality evidence), or at 30-day follow-up (RR 1.40, 95% CI 0.45 to 4.31; 1 trial, 290 participants; low quality evidence).Only one trial, in children with severe anaemia (290 participants), reported adverse transfusion reactions. Only one child in each arm experienced an adverse reaction within 24 hours of transfusion.Transfusion of RBCs of shorter versus standard practice storage duration Eleven trials (40,588 participants) compared transfusion of RBCs of shorter versus standard practice storage duration. Three trials enrolled critically ill term neonates; two of these enrolled very low birth weight neonates. There were no trials in children. Eight trials enrolled critically ill and non-critically ill adults, with most being hospitalised. We judged four trials to be at low risk of bias across all domains with the others having an unclear risk of bias across multiple domains.Transfusion of RBCs of shorter versus standard practice storage duration probably leads to little or no difference in adult in-hospital mortality (RR 1.05, 95% CI 0.97 to 1.14; 4 trials, 25,704 participants; moderate quality evidence), ICU mortality (RR 1.06, 95% CI 0.98 to 1.15; 3 trials, 13,066 participants; moderate quality evidence), or 30-day mortality (RR 1.04, 95% CI 0.96 to 1.13; 4 trials, 7510 participants;moderate quality evidence).Two of the three trials that enrolled neonates reported that there were no adverse transfusion reactions. One trial reported an isolated case of cytomegalovirus infection in participants assigned to the standard practice storage duration group. Two trials in critically ill adults reported data on transfusion reactions: one observed no difference in acute transfusion reactions between arms (RR 0.67, 95% CI 0.19 to 2.36, 2413 participants), but the other observed more febrile nonhaemolytic reactions in the shorter storage duration arm (RR 1.48, 95% CI 1.13 to 1.95, 4919 participants).Trial sequential analysis showed that we may now have sufficient evidence to reject a 5% relative risk increase or decrease of death within 30 days when transfusing RBCs of shorter versus longer storage duration across all patient groups. AUTHORS' CONCLUSIONS The effect of storage duration on clinically important outcomes has now been investigated in large, high quality RCTs, predominantly in adults. There appears to be no evidence of an effect on mortality that is related to length of storage of transfused RBCs. However, the quality of evidence in neonates and children is low. The current practice in blood banks of using the oldest available RBCs can be continued safely. Additional RCTs are not required, but research using alternative study designs, should focus on particular subgroups (e.g. those requiring multiple RBC units) and on factors affecting RBC quality.
PICO Summary
Population
Adults, children, and neonates requiring a red blood cell (RBC) transfusion (22 randomised controlled trials, n= 42,835).
Intervention
Transfusion of RBCs of shorter storage duration.
Comparison
Transfusion of RBCs of longer storage duration; Standard practice storage duration.
Outcome
Transfusion of RBCs of shorter vs. longer storage duration (11 trials, n= 2,249) probably led to little or no difference in mortality at seven-day follow-up (risk ratio (RR) 1.42, 95% confidence interval (CI) 0.66 to 3.06; 1 trial, n= 3,098) or 30-day follow-up (RR 0.85, 95%CI 0.50 to 1.45; 2 trials, n= 1,121) in adults undergoing major elective cardiac or non-cardiac surgery. At 40 weeks gestational age, the effect on the risk of death was uncertain (RR 0.90, 95% CI 0.41 to 1.85; 1 trial, n= 52). The effect of RBCs of shorter vs. longer storage duration on the risk of death in children with severe anaemia was also uncertain within 24 hours of transfusion (RR 1.50, 95% CI 0.43 to 5.25; 2 trials, n= 364), or at 30-day follow-up (RR 1.40, 95% CI 0.45 to 4.31; 1 trial, n= 290). Only one trial, in children with severe anaemia (n= 290), reported adverse transfusion reactions. Only one child in each arm experienced an adverse reaction within 24 hours of transfusion. Transfusion of RBCs of shorter vs. standard practice storage duration (11 trials, n= 40,588) probably led to little or no difference in adult in-hospital mortality (RR 1.05, 95% CI 0.97 to 1.14; 4 trials, n= 25,704), ICU mortality (RR 1.06, 95% CI 0.98 to 1.15; 3 trials, n= 13,066), or 30-day mortality (RR 1.04, 95% CI 0.96 to 1.13; 4 trials, n= 7,510). Two of the three trials that enrolled neonates reported that there were no adverse transfusion reactions. One trial reported an isolated case of cytomegalovirus infection in participants assigned to the standard practice storage duration group. Two trials in critically ill adults reported data on transfusion reactions: one observed no difference in acute transfusion reactions between arms (RR 0.67, 95% CI 0.19 to 2.36, n= 2,413), but the other observed more febrile non-haemolytic reactions in the shorter storage duration arm (RR 1.48, 95% CI 1.13 to 1.95, n= 4,919). Trial sequential analysis showed that we may now have sufficient evidence to reject a 5% relative risk increase or decrease of death within 30 days when transfusing RBCs of shorter vs. longer storage duration across all patient groups.
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6.
Restrictive versus liberal blood transfusion for gastrointestinal bleeding: a systematic review and meta-analysis of randomised controlled trials
Odutayo A, Desborough MJ, Trivella M, Stanley AJ, Doree C, Collins GS, Hopewell S, Brunskill SJ, Kahan BC, Logan RF, et al
The Lancet. Gastroenterology & Hepatology. 2017;2((5)):354-360.
Abstract
BACKGROUND Acute upper gastrointestinal bleeding is a leading indication for red blood cell (RBC) transfusion worldwide, although optimal thresholds for transfusion are debated. METHODS We searched MEDLINE, Embase, CENTRAL, CINAHL, and the Transfusion Evidence Library from inception to Oct 20, 2016, for randomised controlled trials comparing restrictive and liberal RBC transfusion strategies for acute upper gastrointestinal bleeding. Main outcomes were mortality, rebleeding, ischaemic events, and mean RBC transfusion. We computed pooled estimates for each outcome by random effects meta-analysis, and individual participant data for a cluster randomised trial were re-analysed to facilitate meta-analysis. We compared treatment effects between patient subgroups, including patients with liver cirrhosis, patients with non-variceal upper gastrointestinal bleeding, and patients with ischaemic heart disease at baseline. FINDINGS We included four published and one unpublished randomised controlled trial, totalling 1965 participants. The number of RBC units transfused was lower in the restrictive transfusion group than in the liberal transfusion group (mean difference -1.73 units, 95% CI -2.36 to -1.11, p<0.0001). Restrictive transfusion was associated with lower risk of all-cause mortality (relative risk [RR] 0.65, 95% CI 0.44-0.97, p=0.03) and rebleeding overall (0.58, 0.40-0.84, p=0.004). We detected no difference in risk of ischaemic events. There were no statistically significant differences in the subgroups. INTERPRETATION These results support more widespread implementation of restrictive transfusion policies for adults with acute upper gastrointestinal bleeding. FUNDING None.
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7.
Interventions for chronic kidney disease in people with sickle cell disease
Roy NB, Fortin PM, Bull KR, Doree C, Trivella M, Hopewell S, Estcourt LJ
The Cochrane Database of Systematic Reviews. 2017;((7)):CD012380.
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Abstract
BACKGROUND Sickle cell disease (SCD) is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta-globin) genes. SCD can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Kidney disease is a frequent and potentially severe complication in people with SCD.Chronic kidney disease is defined as abnormalities of kidney structure or function, present for more than three months. Sickle cell nephropathy refers to the spectrum of kidney complications in SCD.Glomerular damage is a cause of microalbuminuria and can develop at an early age in children with SCD, and increases in prevalence in adulthood. In people with sickle cell nephropathy, outcomes are poor as a result of the progression to proteinuria and chronic kidney insufficiency. Up to 12% of people who develop sickle cell nephropathy will develop end-stage renal disease. OBJECTIVES To assess the effectiveness of any intervention in preventing or reducing kidney complications or chronic kidney disease in people with SCD (including red blood cell transfusions, hydroxyurea and angiotensin-converting enzyme inhibitor (ACEI)), either alone or in combination with each other. SEARCH METHODS We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 05 April 2016. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register: 13 April 2017. SELECTION CRITERIA Randomised controlled trials comparing interventions to prevent or reduce kidney complications or chronic kidney disease in people with SCD. There were no restrictions by outcomes examined, language or publication status. DATA COLLECTION AND ANALYSIS Two authors independently assessed trial eligibility, extracted data and assessed the risk of bias. MAIN RESULTS We included two trials with 215 participants. One trial was published in 2011 and included 193 children aged 9 months to 18 months, and compared treatment with hydroxyurea to placebo. The second trial was published in 1998 and included 22 adults with normal blood pressure and microalbuminuria and compared ACEI to placebo.We rated the quality of evidence as low to very low across different outcomes according to GRADE methodology. This was due to trials having: a high or unclear risk of bias including attrition and detection bias; indirectness (the available evidence was for children aged 9 months to 18 months in one trial and a small and select adult sample size in a second trial); and imprecise outcome effect estimates of significant benefit or harm. Hydroxyurea versus placebo We are very uncertain if hydroxyurea reduces or prevents progression of kidney disease (assessed by change in glomerular filtration rate), or reduces hyperfiltration in children aged 9 to 18 months, mean difference (MD) 0.58 (95% confidence interval (CI) -14.60 to 15.76 (mL/min per 1.73 m(2))) (one study; 142 participants; very low-quality evidence).In children aged 9 to 18 months, hydroxyurea may improve the ability to concentrate urine, MD 42.23 (95% CI 12.14 to 72.32 (mOsm/kg)) (one study; 178 participants; low-quality evidence).Hydroxyurea may make little or no difference to SCD-related serious adverse events including: incidence of acute chest syndrome, risk ratio (RR) 0.39 (99% CI 0.13 to 1.16); painful crisis, RR 0.68 (99% CI 0.45 to 1.02); and hospitalisations, RR 0.83 (99% CI 0.68 to 1.01) (one study, 193 participants; low-quality evidence).No deaths occurred in the trial. Quality of life was not reported. ACEI versus placeboWe are very uncertain if ACEI reduces proteinuria in adults with SCD who have normal blood pressure and microalbuminuria, MD -49.00 (95% CI -124.10 to 26.10 (mg per day)) (one study; 22 participants; very low-quality evidence). We are very uncertain if ACEI reduce or prevent kidney disease as measured by creatinine clearance. The authors state that creatinine clearance remained constant ove
PICO Summary
Population
Children and adults with sickle cell disease (SCD), (2 studies, n= 215).
Intervention
Red blood cell transfusions, hydroxyurea and angiotensin‐converting enzyme inhibitor (ACEI), either alone or in combination with each other.
Comparison
Placebo, or usual care.
Outcome
Hydroxyurea vs. placebo: Authors were very uncertain if hydroxyurea reduced or prevented progression of kidney disease (assessed by change in glomerular filtration rate), or reduced hyperfiltration in children aged 9 to 18 months, mean difference (MD) 0.58 (mL/min per 1.73 m2). ACEI vs. placebo: Authors were very uncertain if ACEI reduced proteinuria in adults with SCD who have normal blood pressure and microalbuminuria, MD -49.00 (mg per day). Authors were very uncertain if ACEI reduced or prevented kidney disease as measured by creatinine clearance.
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8.
Effect of restrictive versus liberal red cell transfusion strategies on haemostasis: systematic review and meta-analysis
Desborough MJ, Colman KS, Prick BW, Duvekot JJ, Sweeney C, Odutayo A, Jairath V, Doree C, Trivella M, Hopewell S, et al
Thrombosis and Haemostasis. 2017;117((5):):889-898
Abstract
Red cells play a key role in normal haemostasis in vitro but their importance clinically is less clear. The objective of this meta-analysis was to assess if correction of anaemia by transfusing red cells at a high haemoglobin threshold (liberal transfusion) is superior to transfusion at a lower haemoglobin threshold (restrictive transfusion) for reducing the risk of bleeding or thrombotic events. We searched for randomised controlled trials in any clinical setting that compared two red cell transfusion thresholds and investigated the risk of bleeding. We searched for studies published up to October 19, 2016 in The Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, and the Transfusion Evidence Library and ISI Web of Science. Relative risks (RR) or Peto Odds Ratios (pOR) were pooled using a random-effect model. Nineteen randomised trials with 9852 participants were eligible for inclusion in this review. Overall there was no difference in the risk of any bleeding between transfusion strategies (RR 0.91, 95 % confidence interval [CI] 0.74 to 1.12). The risk of severe or life-threatening bleeding was lower with a restrictive strategy (RR 0.75, 95 % CI 0.57 to 0.99). There was no difference in the risk of thrombotic events (RR 0.83, 95 % CI 0.61 to 1.13). The risk of any bleeding was not reduced with liberal transfusion and there was no overall difference in the risk of thrombotic events. Data from the included trials do not support aiming for a high haemoglobin threshold to improve haemostasis. PROSPERO registration number CRD42016035519.
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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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10.
Blood transfusion for preventing primary and secondary stroke in people with sickle cell disease
Estcourt LJ, Fortin PM, Hopewell S, Trivella M, Wang WC
The Cochrane Database of Systematic Reviews. 2017;((1)):CD003146.
Abstract
BACKGROUND Sickle cell disease is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. Sickle cell disease can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Stroke affects around 10% of children with sickle cell anaemia (HbSS). Chronic blood transfusions may reduce the risk of vaso-occlusion and stroke by diluting the proportion of sickled cells in the circulation.This is an update of a Cochrane Review first published in 2002, and last updated in 2013. OBJECTIVES To assess risks and benefits of chronic blood transfusion regimens in people with sickle cell disease for primary and secondary stroke prevention (excluding silent cerebral infarcts). SEARCH METHODS We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 04 April 2016.We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register: 25 April 2016. SELECTION CRITERIA Randomised controlled trials comparing red blood cell transfusions as prophylaxis for stroke in people with sickle cell disease to alternative or standard treatment. There were no restrictions by outcomes examined, language or publication status. DATA COLLECTION AND ANALYSIS Two authors independently assessed trial eligibility and the risk of bias and extracted data. MAIN RESULTS We included five trials (660 participants) published between 1998 and 2016. Four of these trials were terminated early. The vast majority of participants had the haemoglobin (Hb)SS form of sickle cell disease.Three trials compared regular red cell transfusions to standard care in primary prevention of stroke: two in children with no previous long-term transfusions; and one in children and adolescents on long-term transfusion.Two trials compared the drug hydroxyurea (hydroxycarbamide) and phlebotomy to long-term transfusions and iron chelation therapy: one in primary prevention (children); and one in secondary prevention (children and adolescents).The quality of the evidence was very low to moderate across different outcomes according to GRADE methodology. This was due to the trials being at a high risk of bias due to lack of blinding, indirectness and imprecise outcome estimates. Red cell transfusions versus standard care Children with no previous long-term transfusionsLong-term transfusions probably reduce the incidence of clinical stroke in children with a higher risk of stroke (abnormal transcranial doppler velocities or previous history of silent cerebral infarct), risk ratio 0.12 (95% confidence interval 0.03 to 0.49) (two trials, 326 participants), moderate quality evidence.Long-term transfusions may: reduce the incidence of other sickle cell disease-related complications (acute chest syndrome, risk ratio 0.24 (95% confidence interval 0.12 to 0.48)) (two trials, 326 participants); increase quality of life (difference estimate -0.54, 95% confidence interval -0.92 to -0.17) (one trial, 166 participants); but make little or no difference to IQ scores (least square mean: 1.7, standard error 95% confidence interval -1.1 to 4.4) (one trial, 166 participants), low quality evidence.We are very uncertain whether long-term transfusions: reduce the risk of transient ischaemic attacks, Peto odds ratio 0.13 (95% confidence interval 0.01 to 2.11) (two trials, 323 participants); have any effect on all-cause mortality, no deaths reported (two trials, 326 participants); or increase the risk of alloimmunisation, risk ratio 3.16 (95% confidence interval 0.18 to 57.17) (one trial, 121 participants), very low quality evidence. Children and adolescents with previous long-term transfusions (one trial, 79 participants)We are very uncertain whether continuing long-term transfusions reduces the incidence of: stroke, risk ratio 0.22 (95% confidence interval 0.01 to 4.35); or all-cause mortality, Peto odds ratio 8.00 (95% co