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1.
Perioperative transfusion and long-term mortality after cardiac surgery: a meta-analysis
Woldendorp K, Manuel L, Srivastava A, Doane M, Bassin L, Marshman D
General thoracic and cardiovascular surgery. 2023
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Editor's Choice
Abstract
OBJECTIVES Cardiac surgical procedures are associated with a high incidence of periprocedural blood loss and blood transfusion. Although both may be associated with a range of postoperative complications there is disagreement on the impact of blood transfusion on long-term mortality. This study aims to provide a comprehensive review of the published outcomes of perioperative blood transfusion, examined as a whole and by index procedure. METHODS A systematic review of perioperative blood transfusion cardiac surgical patients was conducted. Outcomes related to blood transfusion were analysed in a meta-analysis and aggregate survival data were derived to examine long-term survival. RESULTS Thirty-nine studies with 180,074 patients were identified, the majority (61.2%) undergoing coronary artery bypass surgery. Perioperative blood transfusions were noted in 42.2% of patients and was associated with significantly higher early mortality (OR 3.87, p < 0.001). After a median of 6.4 years (range 1-15), mortality remained significantly higher for those who received a perioperative transfusion (OR 2.01, p < 0.001). Pooled hazard ratio for long-term mortality similar for patients who underwent coronary surgery compared to isolated valve surgery. Differences in long-term mortality for all comers remained true when corrected for early mortality and when only including propensity matched studies. CONCLUSIONS Perioperative red blood transfusion appears to be associated with a significant reduction in long-term survival for patients after cardiac surgery. Strategies such as preoperative optimisation, intraoperative blood conservation, judicious use of postoperative transfusions, and professional development into minimally invasive techniques should be utilised where appropriate to minimise the need for perioperative transfusions.
PICO Summary
Population
Patients undergoing cardiac surgery (39 studies, n= 180,074).
Intervention
Red blood cell (RBC) transfusion.
Comparison
No RBC transfusion.
Outcome
The meta-analysis identified 180,074 patients with follow-up data ranging from 1 to 15 years. The majority (61.2%) of patients underwent coronary artery bypass surgery. Perioperative blood transfusions were noted in 42.2% of patients and was associated with significantly higher early mortality (OR= 3.87). After a median of 6.4 years (range 1, 15), mortality remained significantly higher for those who received a perioperative transfusion (OR= 2.01). Pooled hazard ratio for long-term mortality was similar for patients who underwent coronary surgery compared to isolated valve surgery. Differences in long-term mortality for all comers remained true when corrected for early mortality and when only including propensity matched studies.
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Efficacy of Harmonic Scalpel Versus Bipolar Diathermy in Hemorrhoidectomy: A Systematic Review and Meta-Analysis of Nine Randomized Controlled Trials
Albazee, E., Alenezi, A., Alenezi, M., Alabdulhadi, R., Alhubail, R. J., Ahmad Al Sadder, K., AlDabbous, F., Almutairi, A. N., Almutairi, S. N., Almutairi, A. N., et al
Cureus. 2023;15(2):e34734
Abstract
Hemorrhoidectomy is one of the most common surgical interventions to remove the third and fourth degrees of prolapse hemorrhoid. We carried out this systematic review and meta-analysis of the randomized controlled trials (RCTs) to comprehensively evaluate the efficacy of harmonic scalpel (HS) versus bipolar diathermy (BD) methods in terms of decreasing intraoperative and postoperative morbidities among patients undergoing hemorrhoidectomy. Suitable citations were found utilizing digital medical sources, including the CENTRAL, Web of Science, PubMed, Scopus, and Google Scholar, from inception until December 2022. Only RCTs that matched the inclusion requirements were selected. We used the updated Cochrane risk of bias (ROB) tool (version 2) to assess the quality of the involved citations. The Review Manager (version 5.4 for Windows) was used to perform the pooled analysis. Data were pooled and reported as mean difference (MD) or risk ratio (RR) with a 95% confidence interval (CI) in random-effects models. Overall, there was no significant difference between HS and BD in terms of decreasing intraoperative morbidities like operative time, intraoperative blood loss, mean duration of hospital stay, and mean duration of first bowel movement (P>0.05). Similarly, the rate of postoperative complications like pain, bleeding, urinary retention, anal stenosis, flatus incontinence, and wound edema; was similar in both groups with no significant difference (P>0.05). In conclusion, our pooled analysis revealed there was no substantial difference between HS and BD in terms of intraoperative and postoperative endpoints. Additional RCTs with larger sample sizes are needed to consolidate the power and quality of the presented evidence.
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Drugs to reduce bleeding and transfusion in major open vascular or endovascular surgery: a systematic review and network meta-analysis
Beverly A, Ong G, Kimber C, Sandercock J, Dorée C, Welton NJ, Wicks P, Estcourt LJ
The Cochrane database of systematic reviews. 2023;2(2):Cd013649
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Full text
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Editor's Choice
Abstract
BACKGROUND Vascular surgery may be followed by internal bleeding due to inadequate surgical haemostasis, abnormal clotting, or surgical complications. Bleeding ranges from minor, with no transfusion requirement, to massive, requiring multiple blood product transfusions. There are a number of drugs, given systemically or applied locally, which may reduce the need for blood transfusion. OBJECTIVES To assess the effectiveness and safety of anti-fibrinolytic and haemostatic drugs and agents in reducing bleeding and the need for blood transfusion in people undergoing major vascular surgery or vascular procedures with a risk of moderate or severe (> 500 mL) blood loss. SEARCH METHODS We searched: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL, and Transfusion Evidence Library. We also searched the WHO ICTRP and ClinicalTrials.gov trial registries for ongoing and unpublished trials. Searches used a combination of MeSH and free text terms from database inception to 31 March 2022, without restriction on language or publication status. SELECTION CRITERIA We included randomised controlled trials (RCTs) in adults of drug treatments to reduce bleeding due to major vascular surgery or vascular procedures with a risk of moderate or severe blood loss, which used placebo, usual care or another drug regimen as control. DATA COLLECTION AND ANALYSIS We used standard Cochrane methods. Our primary outcomes were units of red cells transfused and all-cause mortality. Our secondary outcomes included risk of receiving an allogeneic blood product, risk of reoperation or repeat procedure due to bleeding, risk of a thromboembolic event, risk of a serious adverse event and length of hospital stay. We used GRADE to assess certainty of evidence. MAIN RESULTS We included 22 RCTs with 3393 participants analysed, of which one RCT with 69 participants was reported only in abstract form, with no usable data. Seven RCTs evaluated systemic drug treatments (three aprotinin, two desmopressin, two tranexamic acid) and 15 RCTs evaluated topical drug treatments (drug-containing bioabsorbable dressings or glues), including fibrin, thrombin, collagen, gelatin, synthetic sealants and one investigational new agent. Most trials were conducted in high-income countries and the majority of the trials only included participants undergoing elective surgery. We also identified two ongoing RCTs. We were unable to perform the planned network meta-analysis due to the sparse reporting of outcomes relevant to this review. Systemic drug treatments We identified seven trials of three systemic drugs: aprotinin, desmopressin and tranexamic acid, all with placebo controls. The trials of aprotinin and desmopressin were small with very low-certainty evidence for all of our outcomes. Tranexamic acid versus placebo was the systemic drug comparison with the largest number of participants (2 trials; 1460 participants), both at low risk of bias. The largest of these included a total of 9535 individuals undergoing a number of different higher risk surgeries and reported limited information on the vascular subgroup (1399 participants). Neither trial reported the number of units of red cells transfused per participant up to 30 days. Three outcomes were associated with very low-certainty evidence due to the very wide confidence intervals (CIs) resulting from small study sizes and low number of events. These were: all-cause mortality up to 30 days; number of participants requiring an allogeneic blood transfusion up to 30 days; and risk of requiring a repeat procedure or operation due to bleeding. Tranexamic acid may have no effect on the risk of thromboembolic events up to 30 days (risk ratio (RR) 1.10, 95% CI 0.88 to 1.36; 1 trial, 1360 participants; low-certainty evidence due to imprecision). There is one large ongoing trial (8320 participants) comparing tranexamic acid versus placebo in people undergoing non-cardiac surgery who are at high risk of requiring a red cell transfusion. This aims to complete recruitment in April 2023. This trial has primary outcomes of proportion of participants transfused with red blood cells and incidence of venous thromboembolism (DVT or PE). Topical drug treatments Most trials of topical drug treatments were at high risk of bias due to their open-label design (compared with usual care, or liquids were compared with sponges). All of the trials were small, most were very small, and few reported clinically relevant outcomes in the postoperative period. Fibrin sealant versus usual care was the topical drug comparison with the largest number of participants (5 trials, 784 participants). The five trials that compared fibrin sealant with usual care were all at high risk of bias, due to the open-label trial design with no measures put in place to minimise reporting bias. All of the trials were funded by pharmaceutical companies. None of the five trials reported the number of red cells transfused per participant up to 30 days or the number of participants requiring an allogeneic blood transfusion up to 30 days. The other three outcomes were associated with very low-certainty evidence with wide confidence intervals due to small sample sizes and the low number of events, these were: all-cause mortality up to 30 days; risk of requiring a repeat procedure due to bleeding; and risk of thromboembolic disease up to 30 days. We identified one large trial (500 participants) comparing fibrin sealant versus usual care in participants undergoing abdominal aortic aneurysm repair, which has not yet started recruitment. This trial lists death due to arterial disease and reintervention rates as primary outcomes. AUTHORS' CONCLUSIONS Because of a lack of data, we are uncertain whether any systemic or topical treatments used to reduce bleeding due to major vascular surgery have an effect on: all-cause mortality up to 30 days; risk of requiring a repeat procedure or operation due to bleeding; number of red cells transfused per participant up to 30 days or the number of participants requiring an allogeneic blood transfusion up to 30 days. There may be no effect of tranexamic acid on the risk of thromboembolic events up to 30 days, this is important as there has been concern that this risk may be increased. Trials with sample size targets of thousands of participants and clinically relevant outcomes are needed, and we look forward to seeing the results of the ongoing trials in the future.
PICO Summary
Population
Adults undergoing major vascular surgery or vascular procedures with a risk of moderate or severe blood loss (22 randomised controlled trials, n= 3,393).
Intervention
Drug treatments to reduce bleeding: anti-fibrinolytic and haemostatic drugs and agents.
Comparison
Placebo, usual care or another drug regimen.
Outcome
The primary outcomes were units of red blood cells transfused, all-cause mortality and thromboembolic events. There was too little data for a network meta-analysis. The reporting of outcomes was sparse. There was no evidence of increased risk of thromboembolic events with tranexamic acid [low certainty evidence]. The authors reported a need for larger trials with better reporting of post-surgical outcomes.
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Effect of minimally invasive versus conventional aortic root replacement on transfusion and postoperative wound complications in patients: A meta-analysis
Chen, Y., Yu, W., Jiang, Y., Gao, J., Xie, D., Yu, J., Li, W., Liu, Z., Xiong, J.
International wound journal. 2023
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Abstract
We examined whether small incision aortic root replacement could reduce the amount of blood transfusion during operation and the risk of postoperative complications. An extensive e-review of the 4 main databases (PubMed, Cochrane, Web of Science and EMBASE) was carried out to determine all the published trials by July 2023. The search terms used were associated with partial versus full sternotomy and aortic root. This analysis only included the study articles that compared partial and full sternotomy. After excluding articles based on titles or abstracts, selected full-text articles had reference lists searched for any potential further articles. We analysed a total of 2167 subjects from 10 comparable trials. The minimally invasive aortic root graft in breastbone decreased the duration of hospitalization (MD, -2.58; 95% CI, -3.15, -2.01, p < 0.0001) and intraoperative red blood cell transfusion (MD, -1.27; 95% CI, -2.34, -0.19, p = 0.02). However, there were no significant differences in wound infection (OR, 0.88; 95% CI, 0.16, 4.93, p = 0.88), re-exploration for bleeding (OR, 0.96; 95% CI, 0.60, 1.53, p = 0.86), intraoperative blood loss (MD, -259.19; 95% CI, -615.11, 96.73, p = 0.15) and operative time (MD, -7.39; 95% CI, -19.10, 4.32, p = 0.22); the results showed that the microsternotomy did not differ significantly from that of the routine approach. Small sternotomy may be an effective and safe substitute for the treatment of the aorta root. Nevertheless, the wide variety of data indicates that larger, well-designed studies are required to back up the current limited literature evidence showing a benefit in terms of complications like postoperative wound infections or the volume of intraoperative red blood cell transfusion.
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Optimizing Safety and Success: The Advantages of Bloodless Cardiac Surgery. A Systematic Review and Meta-Analysis of Outcomes in Jehovah's Witnesses
Gemelli, M., Italiano, E. G., Geatti, V., Addonizio, M., Cao, I., Dimagli, A., Dokollari, A., Tarzia, V., Gallo, M., Ferrari, E., et al
Current problems in cardiology. 2023;:102078
Abstract
OBJECTIVE Transfusions are extremely frequent after cardiac surgery, and they have a considerable economic burden and impact on outcomes. Optimal patient blood management (PBM) could play a fundamental role in reducing the rate of transfusion and Jehovah's Witnesses (JW) represent the ideal surrogate study population. This meta-analysis compares outcomes of JWs and non-JWs' patients undergoing cardiac surgery, assessing the safety of a bloodless cardiac surgery. METHODS A scoping review was conducted using a search strategy for studies assessing outcomes of JW undergoing cardiac surgery. The primary outcome was perioperative mortality, and a random-effects meta-analysis was performed. RESULTS Ten studies were included in our meta-analysis, involving 780 JW patients refusing any type of transfusion ("JW") and 1182 patients accepting transfusion if needed ("non-JW"). 86% of non-JW patients received at least 1 transfusion. There was no significant difference in terms of perioperative mortality (OR 0.91; 95% CI 0.55 - 1.52; p = 0.72). The volume blood loss was significantly less in the JW (p = 0.001), while the rate of reoperation for bleeding was also lower, but not statistically significative, in the JW (p = 0.16). Both pre-operative and post-operative hemoglobin and hematocrit were significantly higher in the JW. CONCLUSIONS Bloodless cardiac surgery is safe and early outcomes are similar between JW and non-JW patients: optimal patient blood management is fundamental in guarantying these results. Further studies are needed to assess if a limitation of transfusion could have a positive long-term impact on outcomes.
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Recombinant Activated Factor VII (rFVIIa) for Bleeding After Thoracic Aortic Surgery: A Scoping Review of Current Literature
Navarro, R., Bojic, S., Fatima, R., El-Tahan, M., El-Diasty, M.
Journal of cardiothoracic and vascular anesthesia. 2023
Abstract
BACKGROUND Bleeding after surgery on the thoracic aorta is a frequent complication, and can be associated with a significant increase in morbidity and mortality. Recombinant activated factor VII (rFVIIa) was developed initially for treating patients with hemophilia; however, it has been used increasingly "off-label" to achieve hemostasis after thoracic aortic procedures. OBJECTIVE This scoping review aimed to present the available literature on the role of rFVIIa in the management of refractory postoperative bleeding after thoracic aortic surgery. METHODS/RESULTS An electronic database search was conducted using Medline, Embase, Cochrane Library, and Google Scholar in June 2023. The authors included studies that reported the use of rFVIIa in patients undergoing surgical repair of ascending or descending aortic aneurysm or dissection. Single-case reports were excluded. Ten publications with a pooled number of 649 patients (319 patients received rFVIIa and 330 in the control groups) were identified: 3 case series, 6 retrospective studies, and 1 nonrandomized clinical trial. All studies reported the potential role of rFVIIa in correcting coagulopathy and reducing postoperative blood loss in this group of patients. Overall, there was not enough evidence to suggest that rFVIIa was associated with higher rates of thromboembolic complications or mortality. CONCLUSION Limited evidence suggests that rFVIIa may be useful in managing postoperative refractory bleeding in patients undergoing thoracic aortic surgery. However, the impact of rFVIIa on thromboembolic complications and mortality rates remains unclear.
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Red Blood Cell Transfusion Guided by Hemoglobin Only or Integrating Perfusion Markers in Patients Undergoing Cardiac Surgery: A Systematic Review and Meta-Analysis With Trial Sequential Analysis
Putaggio, A., Tigano, S., Caruso, A., La Via, L., Sanfilippo, F.
Journal of cardiothoracic and vascular anesthesia. 2023
Abstract
OBJECTIVE Strategies for red blood cell (RBC) transfusion in patients undergoing cardiac surgery have been traditionally anchored to hemoglobin (Hb) targets. A more physiologic approach would consider markers of organ hypoperfusion. DESIGN The authors conducted a systematic review and meta-analysis with trial sequential analysis of randomized controlled trials (RCTs). SETTING Cardiac surgery. PARTICIPANTS Adult patients. INTERVENTION RBC transfusion targeting only Hb levels compared with strategies combining Hb values with markers of organ hypoperfusion. MEASUREMENTS AND MAIN RESULTS Primary outcomes were the number of RBC units transfused, the number of patients transfused at least once, and the average number of transfusions. Secondary outcomes were postoperative complications, intensive care (ICU) and hospital lengths of stay, and mortality. Only 2 RCTs were included (n = 257 patients), and both used central venous oxygen saturation (ScvO(2)) as a marker of organ hypoperfusion (cut-off: <70% or ≤65%). A transfusion protocol combining Hb and ScvO(2) reduced the overall number of RBC units transfused (risk ratio [RR]: 1.57 [1.33-1.85]; p < 0.0001, I(2) = 0%), and the number of patients transfused at least once (RR: 1.33 [1.16-1.53]; p < 0.0001, I(2) = 41%), but not the average number of transfusions (mean difference [MD]: 0.18 [-0.11 to 0.47]; p = 0.24, I(2) = 66%), with moderate certainty of evidence. Mortality (RR: 1.29, [0.29-5.77]; p = 0.73, I(2) = 0%), ICU length-of-stay (MD: -0.06 [-0.58 to 0.46]; p = 0.81, I(2) = 0%), hospital length-of-stay (MD: -0.05 [-1.49 to 1.39];p = 0.95, I(2) = 0%), and all postoperative complications were not affected. CONCLUSIONS In adult patients undergoing cardiac surgery, a restrictive protocol integrating Hb values with a marker of organ hypoperfusion (ScvO(2)) reduces the number of RBC units transfused and the number of patients transfused at least once without apparent signals of harm. These findings were preliminary and warrant further multicentric research.
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Ultrafiltration in cardiac surgery: Results of a systematic review and meta-analysis
Hensley, N. B., Colao, J. A., Zorrilla-Vaca, A., Nanavati, J., Lawton, J. S., Raphael, J., Mazzeffi, M. A., Wierschke, C., Kostibas, M. P., Cho, B. C., et al
Perfusion. 2023;:2676591231157970
Abstract
Background: Ultrafiltration is used with cardiopulmonary bypass to reduce the effects of hemodilution and restore electrolyte balance. We performed a systematic review and meta-analysis to analyze the effect of conventional and modified ultrafiltration on intraoperative blood transfusion.Methods: Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement, we systematically searched MEDLINE, EMBASE, Web of Science, and Cochrane Library to perform a meta-analysis of studies of randomized controlled trials (RCTs) and observational studies evaluating conventional ultrafiltration (CUF) and modified ultrafiltration (MUF) on the primary outcome of intraoperative red cell transfusions.Results: A total of 7 RCTs (n = 928) were included, comparing modified ultrafiltration (n = 473 patients) to controls (n = 455 patients) and 2 observational studies (n = 47,007), comparing conventional ultrafiltration (n = 21,748) to controls (n = 25,427). Overall, MUF was associated with transfusion of fewer intraoperative red cell units per patient (n = 7); MD -0.73 units; 95% CI -1.12 to -0.35 p = 0.04; p for heterogeneity = 0.0001, I(2) = 55%) compared to controls. CUF was no difference in intraoperative red cell transfusions compared to controls (n = 2); OR 3.09; 95% CI 0.26-36.59; p = 0.37; p for heterogeneity = 0.94, I(2) = 0%. Review of the included observational studies revealed an association between larger volumes (>2.2 L in a 70 kg patient) of CUF and risk of acute kidney injury (AKI).Conclusion: The results of this systematic review and meta-analysis suggest that MUF is associated with fewer intraoperative red cell transfusions. Based on limited studies, CUF does not appear to be associated with a difference in intraoperative red cell transfusion.
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Prevention of cardiac surgery-associated acute kidney injury: a systematic review and meta-analysis of non-pharmacological interventions
Hariri, G., Collet, L., Duarte, L., Martin, G. L., Resche-Rigon, M., Lebreton, G., Bouglé, A., Dechartres, A.
Critical care (London, England). 2023;27(1):354
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Editor's Choice
Abstract
BACKGROUND Cardiac surgery-associated acute kidney injury (CSA-AKI) is frequent. While two network meta-analyses assessed the impact of pharmacological interventions to prevent CSA-AKI, none focused on non-pharmacological interventions. We aim to assess the effectiveness of non-pharmacological interventions to reduce the incidence of CSA-AKI. METHODS We searched PubMed, Embase, Central and clinical trial registries from January 1, 2004 (first consensus definition of AKI) to July 1, 2023. Additionally, we conducted manual screening of abstracts of major anesthesia and intensive care conferences over the last 5 years and reference lists of relevant studies. We selected all randomized controlled trials (RCTs) assessing a non-pharmacological intervention to reduce the incidence of CSA-AKI, without language restriction. We excluded RCTs of heart transplantation or involving a pediatric population. The primary outcome variable was CSA-AKI. Two reviewers independently identified trials, extracted data and assessed risk of bias. Random-effects meta-analyses were conducted to calculate risk ratios (RRs) with 95% confidence intervals (CIs). We used the Grading of Recommendations Assessment, Development, and Evaluation to assess the quality of evidence. RESULTS We included 86 trials (25,855 patients) evaluating 10 non-pharmacological interventions to reduce the incidence of CSA-AKI. No intervention had high-quality evidence to reduce CSA-AKI. Two interventions were associated with a significant reduction in CSA-AKI incidence, with moderate quality of evidence: goal-directed perfusion (RR, 0.55 [95% CI 0.40-0.76], I(2) = 0%; P(het) = 0.44) and remote ischemic preconditioning (RR, 0.86 [0.78-0.95]; I(2) = 23%; P(het) = 0.07). Pulsatile flow during cardiopulmonary bypass was associated with a significant reduction in CSA-AKI incidence but with very low quality of evidence (RR = 0.69 [0.48; 0.99]; I(2) = 53%; P(het) < 0.01). We found high quality of evidence for lack of effect of restrictive transfusion strategy (RR, 1.02 [95% CI 0.92; 1.12; P(het) = 0.67; I(2) = 3%) and tight glycemic control (RR, 0.86 [95% CI 0.55; 1.35]; P(het) = 0.25; I(2) = 26%). CONCLUSIONS Two non-pharmacological interventions are likely to reduce CSA-AKI incidence, with moderate quality of evidence: goal-directed perfusion and remote ischemic preconditioning.
PICO Summary
Population
Adult patients undergoing cardiac surgery such as coronary artery bypass grafting and/or valve surgery (86 randomised controlled trials (RCTs) n= 25,855).
Intervention
Non-pharmacological interventions to reduce the incidence of cardiac surgery-associated acute kidney injury (CSA-AKI): Goal directed perfusion (GDP), pulsatile flow during cardiopulmonary bypass (CPB), minimally invasive extracorporeal circulation (MECC), epidural analgesia, remote ischemic preconditioning (RIPc), tight glycemic control, kidney disease improving global outcomes care bundle, hyperoxia during CPB, restrictive transfusion strategy, high target arterial pressure.
Comparison
Usual care.
Outcome
No intervention had high-quality evidence to reduce CSA-AKI. From the included studies, the most frequent intervention was RIPc (31 RCTs, n= 7,738), MECC, (14 RCTs, n= 1,617) and pulsatile blood flow during CPB (10 RCTs, n= 1,993). Three interventions were associated with a significantly reduced risk of CSA-AKI: GDP, RIPc and pulsatile flow during CPB.
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Preoperative anemia and anemia treatment in cardiac surgery: a systematic review and meta-analysis
Lau, Mpxl, Low, C. J. W., Ling, R. R., Liu, N. S. H., Tan, C. S., Ti, L. K., Kofidis, T., MacLaren, G., Ramanathan, K.
Canadian journal of anaesthesia = Journal canadien d'anesthesie. 2023
Abstract
PURPOSE We aimed to conduct a systematic review and meta-analysis to assess the effects of anemia and anemia severity on patient outcomes in cardiac surgery and determine whether preoperative treatments confer postoperative benefit. SOURCE We searched four international databases for observational and randomized studies published until 1 October 2022. Study quality was assessed via Newcastle-Ottawa scores and the Cochrane Risk-of-Bias 2 tool and certainty of evidence was rated with the Grading of Recommendations, Assessment, Development and Evaluations approach. We conducted random-effects meta-analyses for our primary outcome of mortality, for secondary outcomes including length of stay (LOS) in the hospital and intensive care unit, and for postsurgical complications. As part of a secondary analysis, we analyzed short-term preoperative anemia treatments and conducted trial sequential analysis of randomized trials to assess the efficacy of these treatment programs. PRINCIPAL FINDINGS We included 35 studies (159,025 patients) in our primary meta-analysis. Preoperative anemia was associated with increased mortality (odds ratio [OR], 2.5; 95% confidence interval [CI], 2.2 to 2.9; P < 0.001, high certainty). Study-level meta-regression revealed lower hemoglobin levels and studies with lower proportions of male patients to be associated with increased risk of mortality. Preoperative anemia was also associated with an increase in LOS and postsurgical complications. Our secondary analysis (seven studies, 1,012 patients) revealed short-term preoperative anemia treatments did not significantly reduce mortality (OR, 1.1; 95% CI, 0.65 to 1.9; P = 0.69). Trial sequential analysis suggested that there was insufficient evidence to conclude if treatment programs yield any benefit or harm. CONCLUSIONS Preoperative anemia is associated with mortality and morbidity after cardiac surgery. More research is warranted to test the efficacy of current anemia treatment programs. STUDY REGISTRATION PROSPERO (CRD42022319431); first submitted 17 April 2023.