ABSTRACT Introduction: Blood transfusion is a common practice in cardiac surgery, despite its well-known negative effects. To mitigate blood transfusion-associated risks, identifying patients who are at higher risk of needing this procedure is crucial. Widely used risk scores to predict the need for blood transfusions have yielded unsatisfactory results when validated for the Brazilian population. Methods: In this retrospective study, machine learning (ML) algorithms were compared to predict the need for blood transfusions in a cohort of 495 cardiac surgery patients treated at a Brazilian reference service between 2019 and 2021. The performance of the models was evaluated using various metrics, including the area under the curve (AUC), and compared to the commonly used Transfusion Risk and Clinical Knowledge (TRACK) and Transfusion Risk Understanding Scoring Tool (TRUST) scoring systems. Results: The study found that the model had the highest performance, achieving an AUC of 0.7350 (confidence interval [CI]: 0.7203 to 0.7497). Importantly, all ML algorithms performed significantly better than the commonly used TRACK and TRUST scoring systems. TRACK had an AUC of 0.6757 (CI: 0.6609 to 0.6906), while TRUST had an AUC of 0.6622 (CI: 0.6473 to 0.6906). Conclusion: The findings of this study suggest that ML algorithms may offer a more accurate prediction of the need for blood transfusions than the traditional scoring systems and could enhance the accuracy of predicting blood transfusion requirements in cardiac surgery patients. Further research could focus on optimizing and refining ML algorithms to improve their accuracy and make them more suitable for clinical use. Introduction wellknown well known effects transfusionassociated associated risks crucial population Methods (ML 49 201 2021 metrics AUC, , (AUC) (TRACK (TRUST Results 07350 0 7350 0.735 confidence CI [CI] 07203 7203 0.720 0.7497. 07497 0.7497 . 7497 0.7497) Importantly 06757 6757 0.675 (CI 06609 6609 0.660 0.6906, 06906 0.6906 6906 0.6906) 06622 6622 0.662 06473 6473 0.647 0.6906. Conclusion use 4 20 202 (AUC 0735 735 0.73 [CI 0720 720 0.72 0749 0.749 749 0675 675 0.67 0660 660 0.66 0690 0.690 690 0662 662 0647 647 0.64 2 073 73 0.7 072 72 074 0.74 74 067 67 0.6 066 66 069 0.69 69 064 64 07 7 0. 06 6

ABSTRACT Introduction: Transfusion of red blood cells is recurrent in cardiac surgery despite the well-established deleterious effects. Identifying patients with higher chances of requiring blood transfusion is essential to apply strategic preventive measures to reduce such chances, considering the restricted availability of this product. The most used risk scores to predict blood transfusion are the Transfusion Risk and Clinical Knowledge (TRACK) and Transfusion Risk Understanding Scoring Tool (TRUST). However, these scores were not validated for the Brazilian population. The objective of this study was to assess the accuracy of TRACK and TRUST scores in estimating the need for postoperative transfusion of red blood cell concentrates (TRBCC) after cardiac surgery. Methods: A clinical retrospective study was conducted using the database of a Brazilian reference service composed of patients operated between November 2019 and September 2021. Scores were compared using Mann-Whitney U test. Hosmer-Lemeshow goodness of fit test assessed calibration of the scores. Accuracy was assessed using the area under the receiver operating characteristic curve (AUC). All analyses considered a level of significance of 5%. The study was approved by the research ethics committee (CAAE 55577421.4.0000.5201). Results: This study assessed 498 patients. Only the TRACK score presented good calibration (P=0.238; TRUST P=0.034). AUC of TRACK was 0.678 (95% confidence interval 0.63 to 0.73; P<0.001), showing a significant accuracy. Conclusion: Between the scores analyzed, only the TRACK score showed a good calibration, but low accuracy, to predict postoperative TRBCC after cardiac surgery. Introduction wellestablished well established effects product (TRACK TRUST. . (TRUST) However population (TRBCC Methods 201 2021 MannWhitney Mann Whitney HosmerLemeshow Hosmer Lemeshow AUC. (AUC) 5 5% CAAE 55577421.4.0000.5201. 55577421400005201 55577421.4.0000.5201 55577421 4 0000 5201 55577421.4.0000.5201) Results 49 P=0.238 P0238 P 0 238 (P=0.238 P=0.034. P0034 P=0.034 034 P=0.034) 0678 678 0.67 95% 95 (95 063 63 0.6 0.73 073 73 P<0.001, P0001 P<0.001 , 001 P<0.001) Conclusion analyzed (TRUST 20 202 (AUC 5557742140000520 55577421.4.0000.520 5557742 000 520 P=0.23 P023 23 (P=0.23 P003 P=0.03 03 067 67 9 (9 06 6 0. 0.7 07 7 P000 P<0.00 00 2 555774214000052 55577421.4.0000.52 555774 52 P=0.2 P02 (P=0.2 P00 P=0.0 ( P<0.0 55577421400005 55577421.4.0000.5 55577 P=0. P0 (P=0. P<0. 5557742140000 55577421.4.0000. 5557 P=0 (P=0 P<0 555774214000 55577421.4.0000 555 P= (P= P< 55577421400 55577421.4.000 55 (P 5557742140 55577421.4.00 555774214 55577421.4.0 55577421.4. 55577421.4 55577421.

ABSTRACT Introduction: Transfusion of red blood cells is recurrent in cardiac surgery despite the well-established deleterious effects. Identifying patients with higher chances of requiring blood transfusion is essential to apply strategic preventive measures to reduce such chances, considering the restricted availability of this product. The most used risk scores to predict blood transfusion are the Transfusion Risk and Clinical Knowledge (TRACK) and Transfusion Risk Understanding Scoring Tool (TRUST). However, these scores were not validated for the Brazilian population. The objective of this study was to assess the accuracy of TRACK and TRUST scores in estimating the need for postoperative transfusion of red blood cell concentrates (TRBCC) after cardiac surgery. Methods: A clinical retrospective study was conducted using the database of a Brazilian reference service composed of patients operated between November 2019 and September 2021. Scores were compared using Mann-Whitney U test. Hosmer-Lemeshow goodness of fit test assessed calibration of the scores. Accuracy was assessed using the area under the receiver operating characteristic curve (AUC). All analyses considered a level of significance of 5%. The study was approved by the research ethics committee (CAAE 55577421.4.0000.5201). Results: This study assessed 498 patients. Only the TRACK score presented good calibration (P=0.238; TRUST P=0.034). AUC of TRACK was 0.678 (95% confidence interval 0.63 to 0.73; P<0.001), showing a significant accuracy. Conclusion: Between the scores analyzed, only the TRACK score showed a good calibration, but low accuracy, to predict postoperative TRBCC after cardiac surgery.

OBJETIVO: Avaliar a aplicabilidade do Sistema Europeu de Risco em Operações Cardíacas (EuroSCORE) em pacientes submetidos à cirurgia valvar no Instituto do Coração de Pernambuco. MÉTODOS: Foram incluídos no estudo 840 pacientes operados entre 2001 e 2009. Os prontuários desses doentes continham todas as informações que permitiram calcular o EuroSCORE. O desfecho de interesse foi óbito na internação. Com o objetivo de avaliar a aplicabilidade do EuroSCORE, foi usado o teste não paramétrico de Mann-Whitney. A calibração do modelo foi medida pela comparação da mortalidade observada com a esperada, usando-se o teste de bondade de ajuste de Hosmer-Lemershow. A acurácia do modelo foi avaliada pela curva ROC (receiver operating characteristic curve). RESULTADOS: A comparação entre a mortalidade prevista e a observada, por meio do teste de Hosmer-Lemershow, evidenciou boa capacidade preditiva (P=0,767), assim como quando comparada para cada valor do EuroSCORE Aditivo (P=0,455). Obteve-se uma área sob a curva de ROC de 0,731 (IC95% 0,660 - 0,793), com valor de P<0,001. A mortalidade global prevista foi praticamente idêntica à observada (7,9%). O grupo de baixo risco (EuroSCORE 0-2) era constituído por 345 pacientes, e a mortalidade foi de 3,19%. O grupo de médio risco (EuroSCORE 3-5) compreendeu 364 pacientes, com mortalidade de 7,69%, e o grupo de alto risco (EuroSCORE >6) incluiu 131 pacientes, com mortalidade foi 20,6%. A análise de regressão logística permitiu identificar os seguintes fatores de risco para o óbito: idade acima de 60 anos, sexo feminino, operação prévia, endocardite ativa, cirurgia associada da aorta torácica e arteriopatia extracardíaca. CONCLUSÕES: O EuroSCORE, um método simples e objetivo, revelou-se um preditor satisfatório de mortalidade operatória e, por ele, foram identificados fatores de risco para o óbito em pacientes submetidos à cirurgia valvar no Instituto do Coração de Pernambuco.

OBJECTIVE: To assess the applicability of the European Rysk System in Cardiac Operations (EuroSCORE) in patients undergoing cardiac valve surgery at the Heart Institute of Pernambuco. METHOD: 840 patients operated on between 2001 and 2009, who medical records contained all the informations to calculate the EuroSCORE were included in the study. Hospital death was the end-point of the study. In order to assess the applicability of the EuroSCORE it was used the non parametric test of Mann-Whitney. The calibration of the model was measured by comparing the morbidity observed with that expected, using the Hosmer-Lemeshow Test of Goodness of Fit. The accuracy of the model was evaluated by the ROC curve (receiver operating characteristic curve). RESULTS: The comparison of expected and observed mortality, by Hosmer-Lemershow test, showed good predictive capacity (P = 0.767) as well as when compared to each value of addictive EuroSCORE (P = 0,455). The area of ROC curve was 0.731 (IC 95%, 0.660 - 0.793) with P < 0.001. The global predicted mortality was practically identical to that observed (7.9%). The low-risk group (EuroSCORE 0-2) comprised 345 patients with a mortality of 3.19%. The medium-risk group (EuroSCORE 3-5) comprised 364 patients, with a mortality of 7.69% and the high-risk group (EuroSCORE > 6) included 131 patients, with a mortality of 20.6%. The regression logistic analyses allowed to identify the following risk-factors for death: age > 60 years, gender female, previous operation, active endocarditis, associated surgery of the thoracic aorta and extra-cardiac arteriopathy. CONCLUSION: The EuroSCORE, a simple and objective method, proved to be a satisfactory predictor of operative mortality and risk factors for death in patients submitted to valve cardiac operations in the Heart Institute of Pernambuco.