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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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Editor's Choice
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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Viscoelastic versus conventional coagulation tests to reduce blood product transfusion in patients undergoing liver transplantation: A systematic review and meta-analysis
Aceto P, Punzo G, Di Franco V, Teofili L, Gaspari R, Wolfango Avolio A, Del Tedesco F, Posa D, Lai C, Sollazzi L
European journal of anaesthesiology. 2022
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Editor's Choice
Abstract
BACKGROUND Recent literature suggests viscoelastic test (VET)-guided transfusion management could be associated with reduced blood product administration in patients undergoing liver transplantation. OBJECTIVES To assess the effectiveness of coagulation management guided by VETs compared with conventional coagulation tests (CCTs) in reducing blood product transfusion in patients undergoing liver transplantation. DESIGN Systematic review and meta-analysis of randomised (RCTs) and nonrandomised clinical trials performed according to PRISMA guidelines. The protocol was previously published (PROSPERO CRD42021230213). DATA SOURCES The Cochrane Central Library, PubMed/MEDLINE, Embase and the Transfusion Evidence Library were searched up to 30th January 2022. ELIGIBILITY CRITERIA Setting: operating room. Patients: liver transplantation recipients. Intervention: use of VETs versus CCTs. Main outcome measures: the primary outcome was the mean number of transfused units for each blood product including red blood cells (RBCs), fresh frozen plasma (FFP), platelets (PLTs) and cryoprecipitate. Secondary outcomes included mortality rate, intensive care unit (ICU) and hospital length of stay (LOS). RESULTS Seventeen studies (n = 5345 patients), 15 observational and two RCTs, were included in this review. There was a mean difference reduction in RBCs [mean difference: -1.40, 95% confidence interval (95% CI), -1.87 to -0.92; P < 0.001, I2 = 61%) and FFP units (mean difference: -2.98, 95% CI, -4.61 to -1.35; P = < 0.001; I2 = 98%) transfused in the VETs group compared with the CCTs one. A greater amount of cryoprecipitate was administered in the VETs group (mean difference: 2.71, 95% CI, 0.84 to 4.58; P = 0.005; I2 = 91%). There was no significant difference in the mean number of PLT units, mortality, hospital and ICU-LOS. CONCLUSION Our meta-analysis demonstrated that VETs implementation was associated with reduced RBC and FFP consumption in liver transplantation patients without effects on mortality and hospital and ICU-LOS. The certainty of evidence ranged from moderate to very low. Further well conducted RCTs are needed to improve the certainty of evidence.
PICO Summary
Population
Patients undergoing liver transplantation (17 studies, n= 5,345).
Intervention
Coagulation management guided by viscoelastic tests (VETs group).
Comparison
Conventional coagulation tests (CCTs group).
Outcome
There was a mean difference reduction in red blood cells (mean difference: -1.40, 95% confidence interval (95% CI) -1.87 to -0.92, I2 = 61%) and fresh frozen plasma units (mean difference: -2.98, 95% CI -4.61 to -1.35; I2 = 98%) transfused in the VETs group compared with the CCTs group. A greater amount of cryoprecipitate was administered in the VETs group (mean difference: 2.71, 95% CI, 0.84 to 4.58; I2 = 91%). There was no significant difference in the mean number of platelets units, mortality, hospital and intensive care unit (ICU) and hospital length of stay (LOS).
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Viscoelastometric versus standard coagulation tests to guide periprocedural transfusion in adults with cirrhosis: A meta-analysis of randomized controlled trials
Tangcheewinsirikul N, Moonla C, Uaprasert N, Pittayanon R, Rojnuckarin P
Vox sanguinis. 2021
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Editor's Choice
Abstract
BACKGROUND AND OBJECTIVES Due to rebalanced haemostasis in cirrhosis, viscoelastometric testing (VET) is more accurate than standard coagulation tests (SCTs) in preprocedural haemostatic evaluation, resulting in decreased unnecessary transfusion. We aimed to determine the impact of VET-guided strategy on postprocedural bleeding, periprocedural transfusion rates and quantities, transfusion-related adverse events (TRAEs), lengths of stay (LOS) and mortality from randomized controlled trials (RCTs) of cirrhotic patients. METHODS PubMed and EMBASE were searched for RCTs comparing VET-guided with SCT-guided transfusion in cirrhotic adults undergoing esophagogastroduodenoscopy, liver transplantation or other invasive interventions. Using random-effects models, the pooled risk ratios (RRs) and/or mean differences (MDs) of postprocedural bleeding-free events and the other outcomes were estimated alongside 95% confidence intervals (CIs). RESULTS Of seven included RCTs (n = 421; 72.2% men; mean age 49.1 years), VET-guided transfusion did not change postprocedural bleeding-free statuses (RR 1.05; 95% CI 0.94-1.17). However, VET-based algorithms decreased the rates of fresh frozen plasma (FFP; RR 0.52; 95% CI 0.35-0.77) and platelet transfusions (RR 0.34; 95% CI 0.16-0.73), the quantities of transfused FFP (MD -1.39 units; 95% CI -2.18 to -0.60), platelets (MD -1.06 units; 95% CI -2.01 to -0.12) and cryoprecipitate (MD -7.13 units; 95% CI -14.20 to -0.07) and the risk of TRAEs (RR 0.42; 95% CI 0.27-0.65). The overall mortality rates and LOS were not significantly different between two groups. CONCLUSION Compared with conventional SCT-guided, VET-guided strategy decreases periprocedural plasma and platelet transfusions and TRAEs, without increasing haemorrhagic complications, LOS or mortality in cirrhosis.
PICO Summary
Population
Patients with cirrhosis undergoing esophagogastroduodenoscopy, liver transplantation or other invasive interventions (7 studies, n= 421).
Intervention
Viscoelastometric testing (VET) guided transfusion.
Comparison
Standard coagulation testing (SCT) guided transfusion.
Outcome
VET-guided transfusion did not change post-procedural bleeding-free statuses. However, VET-based algorithms decreased the rates of fresh frozen plasma (FFP) and platelet transfusions, the quantities of transfused FFP (MD -1.39 units), platelets (MD -1.06 units) and cryoprecipitate (MD -7.13 units) and the risk of transfusion-related adverse events. The overall mortality rates and lengths of stay were not significantly different between two groups.
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A Systematic Review of Thromboelastography Utilization in Vascular and Endovascular Surgery
Kim Y, Patel SS, McElroy IE, DeCarlo C, Bellomo TR, Majumdar M, Lella SK, Mohebali J, Dua A
Journal of vascular surgery. 2021
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Editor's Choice
Abstract
OBJECTIVE Thromboelastography (TEG) is diagnostic modality that analyzes real-time blood coagulation parameters. Clinically, TEG primarily allows for directed blood component resuscitation among patients with acute blood loss and coagulopathy. The utilization of TEG has been widely adopted in among other surgical specialties; however, its use in vascular surgery is less prominent. We aimed to provide an up-to-date review of TEG utilization in vascular and endovascular surgery. METHODS Using PRISMA guidelines, a literature review with the Medical Subject Headings (MeSH) terms "TEG and arterial events", "TEG and vascular surgery", "TEG and vascular", "TEG and endovascular surgery", "TEG and endovascular", "TEG and peripheral artery disease", "TEG and prediction of arterial events", "TEG and prediction of complications ", "TEG and prediction of thrombosis", "TEG and prediction of amputation", and "TEG and amputation" was performed in Cochrane and PubMed databases to identify all peer-reviewed studies of TEG utilization in vascular surgery, written between 2000-2021 in the English language. The free text and MeSH subheadings search terms included diagnosis, complications, physiopathology, surgery, mortality, and therapy to further restrict the articles. Studies were excluded if they were not in humans or pertaining to vascular or endovascular surgery. Additionally, case reports and studies with limited information regarding TEG utilization were excluded. Each study was independently reviewed by two researchers to assess for eligibility. RESULTS Of the 262 studies identified through the MeSH strategy, 15 studies met inclusion criteria and were reviewed and summarized. Literature on TEG utilization in vascular surgery spanned cerebrovascular disease (n=3), peripheral arterial disease (n=3), arteriovenous malformations (n=1), venous thromboembolic events (n=7), and perioperative bleeding and transfusion (n=1). In cerebrovascular disease, TEG may predict the presence and stability of carotid plaques, analyze platelet function before carotid stenting, and compare efficacy of antiplatelet therapy after stent deployment. In peripheral arterial disease, TEG has been used to predict disease severity and analyze the impact of contrast on coagulation parameters. In venous disease, TEG may predict hypercoagulability and thromboembolic events among various patient populations. Finally, TEG can be utilized in the postoperative setting to predict hemorrhage and transfusion requirements. CONCLUSIONS This systematic review provides an up-to-date summarization of TEG utilization in multiple facets of vascular and endovascular surgery.
PICO Summary
Population
Patients undergoing vascular and endovascular surgery (15 studies).
Intervention
Systematic review to provide an up-to-date summarization of thromboelastography (TEG).
Comparison
Outcome
Literature on TEG utilization in vascular surgery spanned cerebrovascular disease (n=3), peripheral arterial disease (n=3), arteriovenous malformations (n=1), venous thromboembolic events (n=7), and perioperative bleeding and transfusion (n=1). In cerebrovascular disease, TEG may predict the presence and stability of carotid plaques, analyse platelet function before carotid stenting, and compare efficacy of antiplatelet therapy after stent deployment. In peripheral arterial disease, TEG has been used to predict disease severity and analyse the impact of contrast on coagulation parameters. In venous disease, TEG may predict hypercoagulability and thromboembolic events among various patient populations.
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Techniques for blood loss estimation in major non-cardiac surgery: a systematic review and meta-analysis
Tran A, Heuser J, Ramsay T, McIsaac DM, Martel G
Canadian journal of anaesthesia = Journal canadien d'anesthesie. 2020
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Editor's Choice
Abstract
PURPOSE Estimated blood loss (EBL) is an important tool in clinical decision-making and surgical outcomes research. It guides perioperative transfusion practice and serves as a key predictor of short-term perioperative risks and long-term oncologic outcomes. Despite its widespread clinical and research use, there is no gold standard for blood loss estimation. We sought to systematically review and compare techniques for intraoperative blood loss estimation in major non-cardiac surgery with the objective of informing clinical estimation and research standards. SOURCE A structured search strategy was applied to Ovid Medline, Embase, and Cochrane Library databases from inception to March 2020, to identify studies comparing methods of intraoperative blood loss in adult patients undergoing major non-cardiac surgery. We summarized agreement between groups of pairwise comparisons as visual estimation vs formula estimation, visual estimation vs other, and formula estimation vs other. For each of these comparisons, we described tendencies for higher or lower EBL values, consistency of findings, pooled mean differences, standard deviations, and confidence intervals. PRINCIPLE FINDINGS We included 26 studies involving 3,297 patients in this review. We found that visual estimation is the most frequently studied technique. In addition, visual techniques tended to provide lower EBL values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses likely due to sample size limitations. When accounting for the contextual mean blood loss, similar case-to-case variation exists for all estimation techniques. CONCLUSIONS We found that significant case-by-case variation exists for all methods of blood loss evaluation and that there is significant disagreement between techniques. Given the importance placed on EBL, particularly for perioperative prognostication models, clinicians should consider the universal adoption of a practical and reproducible method for blood loss evaluation. TRIAL REGISTRATION PROSPERO (CRD42015029439); registered: 18 November 2015.PROSPERO (CRD42015029439); registered: 18 November 2015.
PICO Summary
Population
Adult patients undergoing major non-cardiac surgery (26 studies, n= 3,297).
Intervention
Visual estimation of blood loss.
Comparison
Formula estimation of blood loss, and other tecnniques for estimating blood loss.
Outcome
Visual estimation was the most frequently studied technique. Visual techniques tended to provide lower estimated blood loss values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses. When accounting for the contextual mean blood loss, similar case-to-case variation existed for all estimation techniques.
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Diagnostic accuracy of viscoelastic point-of-care identification of hypofibrinogenaemia in cardiac surgical patients: A systematic review
Gibbs NM, Weightman WM
Anaesthesia and intensive care. 2020;:310057x20948868
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Editor's Choice
Abstract
Hypofibrinogenaemia during cardiac surgery may increase blood loss and bleeding complications. Viscoelastic point-of-care tests provide more rapid diagnosis than laboratory measurement, allowing earlier treatment. However, their diagnostic test accuracy for hypofibrinogenaemia has never been reviewed systematically. We aimed to systematically review their diagnostic test accuracy for the identification of hypofibrinogenaemia during cardiac surgery. Two reviewers assessed relevant articles from seven electronic databases, extracted data from eligible articles and assessed quality. The primary outcomes were sensitivity, specificity and positive and negative predictive values. A total of 576 articles were screened and 81 full texts were assessed, most of which were clinical agreement or outcome studies. Only 10 diagnostic test accuracy studies were identified and only nine were eligible (ROTEMdelta 7; TEG5000 1; TEG6S 1, n = 1820 patients) (ROTEM, TEM International GmbH, Munich, Germany; TEG, Haemonetics, Braintree, MA, USA). None had a low risk of bias. Four ROTEM studies with a fibrinogen threshold less than 1.5-1.6 g/l and FIBTEM threshold A10 less than 7.5-8 mm had point estimates for sensitivity of 0.61-0.88; specificity 0.54-0.94; positive predictive value 0.42-0.70; and negative predictive value 0.74-0.98 (i.e. false positive rate 30%-58%; false negative rate 2%-26%). Two ROTEM studies with higher thresholds for both fibrinogen (<2 g/l) and FIBTEM A10 (<9.5 mm) had similar false positive rates (25%-46%), as did the two TEG studies (15%-48%). This review demonstrates that there have been few diagnostic test accuracy studies of viscoelastic point-of-care identification of hypofibrinogenaemia in cardiac surgical patients. The studies performed so far report false positive rates of up to 58%, but low false negative rates. Further diagnostic test accuracy studies of viscoelastic point-of-care identification of hypofibrinogenaemia are required to guide their better use during cardiac surgery.
PICO Summary
Population
Cardiac surgery patients (9 studies, n= 1820).
Intervention
Viscoelastic point of care (POC) tests for the diagnostic test accuracy (DTA) for the identification of hypofibrinogenaemia ROTEM (n= 1692); TEG (n= 128).
Comparison
Laboratory standard.
Outcome
There were no high quality studies of the DTA of viscoelastic POC tests for the identification of hypofibrinogenaemia in cardiac surgical patients. All the 9 DTA studies included had a risk of bias in relation to patient selection, flow and timing of the tests, or blinding of test results. Viscoelastic POC identification of hypofibrinogenaemia, when compared to laboratory fibrinogen measurement was associated with high false positive rates. The studies performed so far report false positive rates of up to 58%, but low false negative rates.
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Comparison of common perioperative blood loss estimation techniques: a systematic review and meta-analysis
Gerdessen L, Meybohm P, Choorapoikayil S, Herrmann E, Taeuber I, Neef V, Raimann FJ, Zacharowski K, Piekarski F
Journal of clinical monitoring and computing. 2020
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Editor's Choice
Abstract
Estimating intraoperative blood loss is one of the daily challenges for clinicians. Despite the knowledge of the inaccuracy of visual estimation by anaesthetists and surgeons, this is still the mainstay to estimate surgical blood loss. This review aims at highlighting the strengths and weaknesses of currently used measurement methods. A systematic review of studies on estimation of blood loss was carried out. Studies were included investigating the accuracy of techniques for quantifying blood loss in vivo and in vitro. We excluded nonhuman trials and studies using only monitoring parameters to estimate blood loss. A meta-analysis was performed to evaluate systematic measurement errors of the different methods. Only studies that were compared with a validated reference e.g. Haemoglobin extraction assay were included. 90 studies met the inclusion criteria for systematic review and were analyzed. Six studies were included in the meta-analysis, as only these were conducted with a validated reference. The mixed effect meta-analysis showed the highest correlation to the reference for colorimetric methods (0.93 95% CI 0.91-0.96), followed by gravimetric (0.77 95% CI 0.61-0.93) and finally visual methods (0.61 95% CI 0.40-0.82). The bias for estimated blood loss (ml) was lowest for colorimetric methods (57.59 95% CI 23.88-91.3) compared to the reference, followed by gravimetric (326.36 95% CI 201.65-450.86) and visual methods (456.51 95% CI 395.19-517.83). Of the many studies included, only a few were compared with a validated reference. The majority of the studies chose known imprecise procedures as the method of comparison. Colorimetric methods offer the highest degree of accuracy in blood loss estimation. Systems that use colorimetric techniques have a significant advantage in the real-time assessment of blood loss.
PICO Summary
Population
Adult surgery and obstetric patients (90 in vitro and in vivo studies).
Intervention
Visual blood loss estimation methods.
Comparison
Several methods including: gravimetric and colorimetric methods.
Outcome
The mixed effect meta-analysis showed the highest correlation to the reference for colorimetric methods (0.93), followed by gravimetric (0.77) and finally visual methods (0.61). The bias for estimated blood loss (ml) was lowest for colorimetric methods (57.59) compared to the reference, followed by gravimetric (326.36) and visual methods (456.51). Colorimetric methods offer the highest degree of accuracy in blood loss estimation.
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Patient blood management interventions do not lead to important clinical benefits or cost-effectiveness for major surgery: a network meta-analysis
Roman MA, Abbasciano RG, Pathak S, Oo S, Yusoff S, Wozniak M, Qureshi S, Lai FY, Kumar T, Richards T, et al
Br J Anaesth. 2020
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Editor's Choice
Abstract
BACKGROUND Patient blood management (PBM) interventions aim to improve clinical outcomes by reducing bleeding and transfusion. We assessed whether existing evidence supports the routine use of combinations of these interventions during and after major surgery. METHODS Five systematic reviews and a National Institute of Health and Care Excellence health economic review of trials of common PBM interventions enrolling participants of any age undergoing surgery were updated. The last search was on June 1, 2019. Studies in trauma, burns, gastrointestinal haemorrhage, gynaecology, dentistry, or critical care were excluded. The co-primary outcomes were: risk of receiving red cell transfusion and 30-day or hospital all-cause mortality. Treatment effects were estimated using random-effects models and risk ratios (RR) with 95% confidence intervals (CIs). Heterogeneity assessments used I(2). Network meta-analyses used a frequentist approach. The protocol was registered prospectively (PROSPERO CRD42018085730). RESULTS Searches identified 393 eligible randomised controlled trials enrolling 54 917 participants. PBM interventions resulted in a reduction in exposure to red cell transfusion (RR=0.60; 95% CI 0.57, 0.63; I(2)=77%), but had no statistically significant treatment effect on 30-day or hospital mortality (RR=0.93; 95% CI 0.81, 1.07; I(2)=0%). Treatment effects were consistent across multiple secondary outcomes, sub-groups and sensitivity analyses that considered clinical setting, type of intervention, and trial quality. Network meta-analysis did not demonstrate additive benefits from the use of multiple interventions. No trial demonstrated that PBM was cost-effective. CONCLUSIONS In randomised trials, PBM interventions do not have important clinical benefits beyond reducing bleeding and transfusion in people undergoing major surgery.
PICO Summary
Population
Patients of any age undergoing cardiovascular, neoplastic, orthopaedic, gastrointestinal, urology, organ transplantation, plastic, or maxillofacial surgery (393 studies, n= 54,917).
Intervention
Patient blood management (PMB) interventions during and after major surgery.
Comparison
No PBM intervention, or alternative goal-directed therapy.
Outcome
PBM interventions resulted in a reduction in exposure to red cell transfusion but had no statistically significant treatment effect on 30-day or hospital mortality. Treatment effects were consistent across multiple secondary outcomes, sub-groups and sensitivity analyses that considered clinical setting, type of intervention, and trial quality. Network meta-analysis did not demonstrate additive benefits from the use of multiple interventions. No trial demonstrated that PBM was cost-effective.