Randomized trials and cohort studies have shown sex differences in the implantation and response to Cardiac Resynchronization Therapy (CRT). Furthermore, gender roles are associated with precipitants of congestive heart failure. Cohort studies are well-suited to assessing implantation rates, long-term outcomes, and the role of sex and gender. Therefore, we systematically identified cohort studies that reported outcomes of CRT and evaluated the following: 1) prevalence and temporal changes in sex and gender reporting and analysis; and 2) sex differences in the implantation and response to CRT. Sex was increasingly considered but remained inadequately reported and analyzed. Gender was not considered in the studies. In clinical practice, fewer women received devices, despite benefiting from CRT more than men. Of note, the difference in response may be confounded by differences in the clinical profiles of men and women. There is a need for better integration of sex and gender in studies to understand better the reasons leading to the observed differences.

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The present study provides an example of implementing the difference in differences (DD) estimator for a two-group, pretest-posttest design with K-12 educational intervention data. The goal is to explore the basis for causal inference via Rubin's potential outcomes framework. The DD method is introduced to educational researchers, as it is seldom implemented in educational research. DD analytic methods' mathematical formulae and assumptions are explored to understand the opportunity and the challenges of using the DD estimator for causal inference in educational research. For this example, the teacher intervention effect is estimated with multi-cohort student outcome data. First, the DD method is used to detect the average treatment effect (ATE) with linear regression as a baseline model. Second, the analysis is repeated using linear regression with cluster robust standard errors. Finally, a linear mixed effects analysis is provided with a random intercept model. Resulting standard errors, parameter estimates, and inferential statistics are compared among these three analyses to explore the best holistic analytic method for this context.

No description available.

Submitted by Ronildo Prado (ronisp@ufscar.br) on 2017-07-19T10:44:04Z No. of bitstreams: 1 TeseSRBJ.pdf: 5473127 bytes, checksum: 6ad9d0f7d24cadafbff18e445b8736d1 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-07-19T10:44:16Z (GMT) No. of bitstreams: 1 TeseSRBJ.pdf: 5473127 bytes, checksum: 6ad9d0f7d24cadafbff18e445b8736d1 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-07-19T10:44:27Z (GMT) No. of bitstreams: 1 TeseSRBJ.pdf: 5473127 bytes, checksum: 6ad9d0f7d24cadafbff18e445b8736d1 (MD5) / Made available in DSpace on 2017-07-19T10:45:12Z (GMT). No. of bitstreams: 1 TeseSRBJ.pdf: 5473127 bytes, checksum: 6ad9d0f7d24cadafbff18e445b8736d1 (MD5) Previous issue date: 2016-12-16 / Não recebi financiamento / Introduction. The datasets used in observational studies have instances belonging to two distinct groups (i.e. treatment group and control group), which are compared in order to estimate the effect of the treatment over the results. For such, in one of the approaches, called Propensity Score Matching (PSM), the propensity score for the instances of both groups is estimated and, subsequently, the correspondence of these instances is performed based on the values for the propensity score. The propensity score is the probability of attribution of a treatment based on the observed characteristics (e.g. income, sex and age). In this context, the logistic regression is widely used to estimate the propensity score and there is an great variety of instance correspondence methods. Objective. This doctor´s thesis has as its main objective to investigate computational alternatives in order to improve the quality of the instance correspondence in datasets that are manipulated in observational studies. Methodology. Techniques that estimate the propensity score and methods to perform the instance correspondence in observational studies were investigated. Thus, it was possible to investigate how the identical characteristics of the instances could be exploited in a new process to perform correspondence and, how ensembles could substitute the logistic regression by estimating the propensity scores of the instances, in the context of the PSM process. Proposal. This thesis proposes a new approach in the context of the PSM process, called “SEnsembles”, which aims to improve the quality of instance correspondence based on two main processes, which use techniques that separately consider the identical characteristics of the instances and the ensembles of regressors, more precisely, bagging, random forest and boosting. Results. The proposed approach “SEnsembles” improves the quality of the instance correspondence for the majority of calipers used (i.e. zero, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) when compared to the baseline Nearest Neighbor Matching (NNM). Based on the experiments, when there was an improvement over the baseline, the technique that separates the identical characteristics of the instances presented improvements of up to 53.8% in the quality of correspondence, with an average of gains of 12.1%; and only 2.7% of average in the reduction of the number of pairs of instances matched. The technique which substituted the logistic regression for ensembles of regressors, in turn, presented the best correspondence with the caliper zero and with the values 0.20, 0.25 and 0.30, with improvements of up to 36.3% and an average of gains of 12.7%; and a slightly reduction of 7.6% in the number of pairs of instances matched. / Introdução. Os conjuntos de dados manipulados em estudos observacionais possuem instâncias pertencentes a dois grupos distintos (i.e. grupo de tratamento e grupo de controle), as quais são comparadas para estimar o efeito do tratamento sobre os resultados. Para isso, em uma das abordagens, chamada de Propensity Score Matching (PSM), estima-se o escore de propensão para as instâncias de ambos os grupos e, em seguida, efetua-se a correspondência dessas instâncias com base nos valores dos escores de propensão. O escore de propensão é a probabilidade de atribuição de um tratamento com base nas características observadas (por exemplo, renda, sexo e idade). Neste contexto, a regressão logística é amplamente utilizada para estimar o escore de propensão e há uma ampla variedade de métodos de correspondência de instâncias. Objetivo. Esta pesquisa de doutorado tem como objetivo principal investigar alternativas computacionais para melhorar a qualidade das correspondências de instâncias em conjuntos de dados que são manipulados em estudos observacionais. Metodologia. Investigou-se técnicas que estimam o escore de propensão e métodos para se efetuar a correspondência das instâncias em estudos observacionais. Assim, foi possível investigar como as características idênticas das instâncias poderiam ser exploradas em um novo processo de correspondência e, como ensembles, mais precisamente, bagging, random forest e boosting, poderiam substituir a regressão logística ao estimar os escores de propensão das instâncias, no contexto do processo de PSM. Proposta. Esta pesquisa propõe uma nova abordagem no contexto do processo PSM, denominada “SEnsembles”, que visa melhorar a qualidade da correspondência das instâncias com base em 2 processos principais, os quais utilizam técnicas que considerem em separado as características idênticas das instâncias e os ensembles de regressores, mais precisamente, bagging, random forest e boosting. Resultados. A abordagem proposta “SEnsembles” melhorou a qualidade da correspondência de instâncias para a maioria dos calipers utilizado (zero, 0,05, 0,10, 0,15, 0,20, 0,25 e 0,30) quando comparada ao baseline Nearest Neighbor Matching (NNM). Com base nos experimentos, quando houve ganho, a técnica que separa as características idênticas das instâncias proporcionou ganhos de até 53,8% na qualidade da correspondência, com média de 12,1% de melhoria e 2,7% de redução média do número de pares de instâncias correspondidas. Já a técnica que substituiu a regressão logística pelos ensembles proporcionou as melhores correspondências com o caliper zero e com os valores 0,20, 0,25 e 0,30, com ganhos de até 36,3% e, com média de 12,7% de melhoria e 7,6% de redução do número de pares de instâncias correspondidas.

Objectives: The EZSCAN is a non-invasive device that, by evaluating sweat gland function, may detect subjects with type 2 diabetes mellitus (T2DM). The aim of the study was to conduct a systematic review and meta-analysis including studies assessing the performance of the EZSCAN for detecting cases of undiagnosed T2DM. Methodology/Principal findings: We searched for observational studies including diagnostic accuracy and performance results assessing EZSCAN for detecting cases of undiagnosed T2DM. OVID (Medline, Embase, Global Health), CINAHL and SCOPUS databases, plus secondary resources, were searched until March 29, 2017. The following keywords were utilized for the systematic searching: type 2 diabetes mellitus, hyperglycemia, EZSCAN, SUDOSCAN, and sudomotor function. Two investigators extracted the information for meta-analysis and assessed the quality of the data using the Revised Version of the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) checklist. Pooled estimates were obtained by fitting the logistic-normal random-effects model without covariates but random intercepts and using the Freeman-Tukey Arcsine Transformation to stabilize variances. Heterogeneity was also assessed using the I2 measure. Four studies (n = 7,720) were included, three of them used oral glucose tolerance test as the gold standard. Using Hierarchical Summary Receiver Operating Characteristic model, summary sensitivity was 72.0% (95%CI: 60.0%– 83.0%), whereas specificity was 56.0% (95%CI: 38.0%– 74.0%). Studies were very heterogeneous (I2 for sensitivity: 79.2% and for specificity: 99.1%) regarding the inclusion criteria and bias was present mainly due to participants selection. Conclusions: The sensitivity of EZSCAN for detecting cases of undiagnosed T2DM seems to be acceptable, but evidence of high heterogeneity and participant selection bias was detected in most of the studies included. More studies are needed to evaluate the performance of the EZSCAN for undiagnosed T2DM screening, especially at the population level.

The objectives of this thesis were to synthesize existing RCT evidence and post-market observational evidence of TNF-α inhibitors in IBD. Two separate systematic reviews were performed: an overview of systematic reviews of RCTs, and a systematic review of post-market observational studies of TNF-α inhibitors in Crohn’s disease and ulcerative colitis. The overview of systematic reviews included 37 studies. RCT evidence demonstrated superiority of all agents to placebo in Crohn’s disease and ulcerative colitis, with no increased risk of malignancy or serious adverse events. Network meta-analyses have not shown superiority of any agent compared to another. The second systematic review included 255 studies. Included studies were deemed to be unamenable to pooling with substantial methodological and clinical diversity. Available evidence is insufficient to determine whether real-world effectiveness and safety is consistent with RCTs, but suggests no increased risk of malignancy and no difference in efficacy between adalimumab and infliximab.

Introdução: A obesidade é uma doença crônica de incidência global e crescente que se tornou nas últimas décadas um dos maiores problemas de saúde pública nas sociedades urbanas. A intervenção cirúrgica, ou cirurgia bariátrica, tem sido apontada como eficaz no tratamento das formas graves de obesidade e a derivação gástrica em Y de Roux (DGYR) é o tipo mais realizado no mundo e no Brasil. O acompanhamento contínuo de todos os indivíduos submetidos à DGYR por equipe multidisciplinar é recomendado por se tratar de uma cirurgia de grande porte com riscos de complicações em longo prazo, entre elas as deficiências nutricionais. Por isso, as consultas nutricionais pós-operatórias são um componente importante desse seguimento. Objetivos: Estimar a prevalência de adesão ao seguimento nutricional ambulatorial pós-cirurgia bariátrica e avaliar a associação dessa adesão com fatores selecionados em um grupo de obesos moderados com comorbidades e obesos mórbidos submetidos à DGYR. Métodos: Estudo de coorte retrospectiva utilizando-se dados de prontuários hospitalares de 241 adultos de ambos os sexos submetidos à derivação gástrica pelo Sistema Único de Saúde entre 2006 e 2008 no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Considerou-se aderente o indivíduo que compareceu a quatro ou mais consultas nutricionais nos 12 primeiros meses após a cirurgia. Para estimar a associação da adesão ao seguimento nutricional pós-cirúrgico com os fatores idade, sexo, estado conjugal, escolaridade, situação empregatícia, distância entre a residência e o hospital, estratégias para perda de peso no período pré-operatório, índice de massa corpórea (IMC) no précirúrgico imediato, presença de comorbidades e duração da internação após a cirurgia, foram calculadas as Razões de Prevalência (RP) e os intervalos de 95% de confiança (IC 95%); para a análise ajustada utilizou-se regressão múltipla de Poisson. Resultados: A população de estudo foi caracterizada pelo predomínio de mulheres (80,9%), pela média de idade de 44,4 anos (±11,6), pela média de IMC pré-operatório de 47,2kg/m2 (±6,16) e 78,4% dos participantes apresentaram uma ou mais comorbidades. Convivência com companheiro foi relatada por 51,5% da população, 41,9% referiram ter ensino fundamental incompleto como nível de escolaridade, 50,9% não possuíam atividade remunerada, 44,7% residiam à distância de até 16 km do hospital e 11,6% ficaram internados por seis ou mais dias após a cirurgia. A prevalência de adesão nessa população foi de 56,0% (IC 95% 49,7-62,3). A análise multivariada revelou que somente duração da internação maior ou igual a seis dias foi associada à adesão ao seguimento nutricional pós-cirúrgico (RP=1,46 IC 95% 1,15-1,86). Conclusões: A prevalência de adesão encontrada nesta população foi semelhante às dos estudos internacionais, mas menor do que a prevalência mínima de 75% recomendada para que o centro seja reconhecido como de excelência em cirurgia bariátrica. Os indivíduos que ficaram internados por mais tempo no pós-cirúrgico mostraram-se significantemente mais aderentes ao seguimento nutricional, podendo sugerir que o maior contato desses com a equipe multiprofissional pode ter contribuído para aumentar a percepção da gravidade da doença e da necessidade de cuidados contínuos com a saúde, e consequentemente ter levado à maior assiduidade às consultas ambulatoriais / Introduction: Obesity is a global chronic disease with increasing incidence during the past decades and has become one of the major public health problems in the urban societies. The surgical intervention, or bariatric surgery, has been considered as an effective treatment of the severe forms of obesity and the Roux-en-Y gastric bypass (RYGB) has been the commonest surgical procedure worldwide, including in Brazil. The long term outpatient postoperative follow up after bariatric surgery by a multidisciplinary team has been recommended to all individuals submitted to RYGB because it is a major surgery which can cause complications such as nutritional deficiencies. Therefore, nutritional assessment in the postoperative period is an important component of the follow up. Objectives: To estimate the prevalence of adherence to outpatient postoperative nutritional follow up after bariatric surgery and to analyze the association between adherence and selected factors in a group of moderately obese with comorbidities and morbidly obese adults who underwent RYGB. Methods: Retrospective cohort study using data from hospital records of 241 adults of both sexes who were submitted to RYGB by the Unified Health System between 2006 and 2008 at the Hospital das Clínicas - Medical School, University of São Paulo. It was considered adherent the individuals who attended four or more nutritional appointments in the first 12 months after surgery. To estimate the association between adherence to postoperative nutritional follow up and factors such us age, sex, marital status, education, employment status, distance between home and hospital, strategies for weight loss in the preoperative period, body mass index (BMI) in the immediate pre-surgical, presence of comorbidities and duration of hospitalization after surgery, were calculated the Prevalence Ratios (PR) and the 95% confidence intervals (95% CI); for the adjusted analysis, Poisson multiple regression was used. Results: The study population was characterized by the predominance of women (80.9%), the mean age of 44.4 years (±11.6), the mean of preoperative BMI of 47.2kg/m2 (±6.16) and 78.4% of participants presented one or more comorbidities. Living with partner was reported by 51.5% of the population, 41.9% had incomplete primary education level, 50.9% had no paid work, 44.7% lived at a distance of up to 16km to the hospital and 11.6% were hospitalized for six or more days after surgery. The prevalence ratio of adherence in this population was 56.0% (95% CI 49.7- 62.3). Multivariate analysis revealed that only length of hospital stay greater than or equal to six days was associated with adherence to nutritional follow up in the postoperative period (PR=1.46 95% CI 1.15-1.86). Conclusions: The prevalence of adherence found in this population was similar to those of international studies, but less than the minimum prevalence of 75% recommended for services to be recognized as a bariatric surgery center of excellence. Individuals who were hospitalized for longer than six days after surgery were significantly more adherent to the nutritional follow-up. This may have happened because they had longer contact with the multidisciplinary team which may have contributed to increase their perception of disease severity and the need for long term health care, and consequently, it may have led to higher assiduity to the nutritional appointments

La médecine fondée sur les preuves a conféré à l’essai contrôlé randomisé (ECR) le plus haut niveau de preuve dans l’évaluation de l’effet des médicaments, et par extension de toute intervention en santé. Cependant, le recours aux études observationnelles s’avère également nécessaire (i) pour conforter, en situation réelle, les résultats issus des ECR dont la validité externe est limitée, (ii) dans des situations, notamment lorsqu’il s’agit d’interventions complexes, où l’ECR n’est pas toujours réalisable pour des questions éthiques et/ou organisationnelles. Toutefois, les études observationnelles sont sujettes à différents types de biais, et notamment au biais d’indication. Ce travail de thèse explore les différentes techniques d’analyse statistique des résultats permettant de maîtriser ce biais. Dans une première partie, les aspects théoriques ont été abordés. Les différentes techniques disponibles ont été identifiées, analysées et comparées : les techniques d’ajustement multivarié, celles utilisant un score de propension (SP) et celles utilisant une variable instrumentale (VI). Pour approfondir les connaissances sur la question, une revue systématique de la littérature a été effectuée. Elle a mis en évidence la faible concordance entre les résultats obtenus en utilisant un SP et ceux obtenus en utilisant une VI, lorsque ces deux techniques étaient utilisées dans une même étude pour évaluer la même intervention. Dans une seconde partie, l’utilisation de SP et/ou VI a été testée dans trois exemples d’évaluation d’interventions complexes à partir de données de pratiques courantes recueillies dans le cadre de deux études observationnelles de cohorte : (i) l’évaluation de l’effet d’un réseau de soins spécialisé dans l’insuffisance cardiaque (IC) sur la mortalité ; (ii) l’évaluation de l’effet des stratégies médicamenteuses appropriées dans l’IC sur la mortalité ; (iii) l’évaluation de l’effet des stratégies antithrombotiques chez les patients hémodialysés sur le risque hémorragique. / Evidence-based medicine placed randomized controlled trials (RCT) at the highest level of evidence to evaluate the effects of medications and, by extension, of all health interventions. Nevertheless, observational studies are necessary (i) to support, in real-world settings, the results of RCTs, the external validity of which is limited, and (ii) in situations where RCTs are not feasible for ethical or practical reasons, particularly when evaluating complex interventions. However, observational studies are particularly prone to confounding by indication. This thesis focuses on analytical methods to reduce this bias. In its first part, the theoretical aspects were addressed. Available methods were identified, reviewed and compared: multivariate adjustment methods, methods using a propensity score (PS) and methods using an instrumental variable (IV). To further knowledge on this issue, a systematic literature review was performed. This review revealed that more and more observational studies simultaneously use PS and IV approaches to evaluate the same intervention, often leading to nonconcordant results that may be dif?cult to interpret. In a second part, the use of PS and/or VI methods was tested in three evaluations of complex interventions in real-world settings, using data from two cohort studies: (i) to evaluate the effectiveness on mortality of a community-based multidisciplinary disease management programme for heart failure (HF) patients; (ii) to evaluate the effectiveness of recommended drug prescriptions on mortality in patients with HF; (iii) to evaluate the effect of antiplatelet and anticoagulant therapies on the risk of major bleeding events in chronic hemodialysis patients

OBJETIVOS: O objetivo do estudo foi avaliar se a transfusão de hemácias no intraoperatório de cirurgia cardíaca com circulação extracorpórea está associada a complicações clínicas incluindo choque cardiogênico, arritmia, insuficiência renal aguda, isquemia miocárdica, choque séptico, necessidade de reintubação orotraqueal, acidente vascular cerebral ou mortalidade durante a internação hospitalar. DESENHO: Estudo clínico de coorte retrospectivo e unicêntrico com escore de propensão, realizado no Instituto do Coração (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. PACIENTES: Pacientes adultos submetidos à cirurgia cardíaca eletiva com circulação extracorpórea no período de janeiro de 2004 a dezembro de 2008. DESFECHO PRIMÁRIO: Complicações clínicas durante a internação hospitalar (choque cardiogênico, arritmia, insuficiência renal aguda, isquemia miocárdica, choque séptico, necessidade de reintubação orotraqueal, acidente vascular cerebral ou mortalidade hospitalar). DESFECHO SECUNDÁRIO: 1- Avaliar o efeito da transfusão de hemácias no intraoperatório no tempo livre de inotrópicos e vasopressores, tempo de ventilação mecânica e tempo de permanência na UTI e internação hospitalar. 2- Avaliar o efeito do número das unidades de hemácias transfundidas no intraoperatório na ocorrência de mortalidade hospitalar, choque cardiogênico, arritmia, isquemia miocárdica, choque séptico, acidente vascular cerebral e reintubação orotraqueal. 3- Avaliar o efeito da anemia à admissão e durante internação hospitalar na ocorrência de complicações pós-operatórias. INTERVENÇÃO: Não houve intervenção. RESULTADOS: Foram incluídos 2851 pacientes na análise final, dos quais 1471(51,6%) foram expostos a transfusão de hemácias e 1380 (48,4%) não receberam transfusão no intraoperatório. Os pacientes transfundidos apresentaram maior incidência das seguintes complicações: mortalidade (2,1% vs 0,4%, P < 0,001), insuficiência renal aguda (9,1% vs 3,9%, P<0,001), reintubação orotraqueal (3,8% vs 1,4%, P < 0,001) e choque séptico (2,2% vs 0,4%, P < 0,001). Os pacientes transfundidos também apresentaram maior tempo de internação hospitalar [16 dias (12-23) vs 13 dias (9-18), P < 0,001] e em unidade de terapia intensiva [3 dias (2-6) vs 2 dias (2-4), P < 0,001]. A concentração da hemoglobina menor que 9 g/dL ocorreu em 1847 pacientes (64,7%) durante a internação hospitalar e foi associada a maior risco de insuficiência renal aguda e de acidente vascular cerebral. O escore de propensão identificou 588 pacientes pareados em relação à exposição à transfusão, e essa análise demonstrou que a transfusão intraoperatória de hemácias não aumentou a ocorrência de complicações no período de internação hospitalar. Contudo a transfusão de 4 ou mais unidades de hemácias está associada a maior ocorrência de mortalidade hospitalar, choque cardiogênico e IRA, maior incidência de reintubação orotraqueal, choque séptico e AVC. Além de uma relação direta entre as unidades de hemácias transfundidas e a ocorrência de morte. CONCLUSÃO: Esse estudo observacional demonstrou que a anemia é frequentemente detectada no pós-operatório de cirurgia cardíaca, e está associada a maior incidência de complicações. Além disso, a transfusão de hemácias no intraoperatório não modifica a ocorrência das complicações pós-operatórias em pacientes submetidos a cirurgia cardíaca. No entanto a transfusão de 4 ou mais hemácias está associada a maior incidência de complicações clínicas, além de uma relação dose-dependente. Estratégias como detecção precoce de anemia e emprego de técnicas alternativas à transfusão no manejo devem ser estimuladas no ambiente perioperatório / OBJECTIVE: The objective of this study was to evaluate whether the transfusion of red blood cells in the intraoperative cardiac surgery with extracorporeal circulation is associated with complications after cardiac surgery. DESIGN: A retrospective cohort study with a propensity score analysis, performed at Instituto do Coração (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. PATIENTS: Adult patients undergoing elective cardiac surgery with cardiopulmonary bypass in the period of January to 2008 December. PRIMARY OUTCOME: Clinical complications during hospital stay (cardiogenic shock, arrhythmia, cardiogenic shock, acute kidney injury, myocardial ischemia, septic shock, tracheal reintubation, stroke or hospital mortality). SECONDARY OUTCOME: 1- Evaluate the effect of intraoperative red blood cell transfusion in inotropic and vasopressor free time, mechanical ventilation time, length of ICU stay and hospital stay. 2- Evaluate the effect of the number of units of transfused red blood cells intraoperatively on the occurrence of hospital mortality, cardiogenic shock, arrhythmia, myocardial ischemia, septic shock, stroke and orotracheal reintubation. 3- Evaluate the effect of anemia on admission and during hospitalization in the occurrence of postoperative complications. RESULTS: In the final analysis, 2851 patients were included. Of these patients, 1471(51.6%) were exposed to red blood cell transfusion (RBC) and 1380 (48.4%) were not exposed to RBC during intraoperative. Transfused patients had higher incidence of the following complications: mortality (2.1% vs. 0.4%, P < 0.001), acute kidney injury (9.1% vs. 3.9%, P < 0,001), tracheal reintubation (3.8% vs. 1.4%, P < 0.001) and septic shock (2.2% vs. 0.4%, P < 0.001). Transfused patients also had a longer length of hospital stay [16 days (12-23) vs. 13 days (9-18), P<0.001] and prolonged intensive care unit stay [3 days (2-6) vs. 2 days (2-4), P < 0.001]. Hemoglobin lower than 9 g/dL was found in 1847 patients (64.7%) during hospital stay and was associated to a higher risk of acute kidney injury and stroke. The propensity score identified 588 paired patients in relation to transfusion exposure, and this analysis demonstrated that intraoperative transfusion of red blood cells did not increase the occurrence of complications during hospitalization. However, transfusion of 4 or more units of red blood cells is associated with a higher occurrence of hospital mortality, cardiogenic shock and acute renal failure, a higher incidence of orotracheal reintubation, septic shock and stroke. In addition to a direct relationship between the units of transfused red blood cells and the occurrence of death. CONCLUSIONS: This observational study demonstrated that anemia is frequently detected in the postoperative period of cardiac surgery, and is associated with a higher incidence of complications. In addition, red blood cell transfusion in the intraoperative does not modify the occurrence of postoperative complications in patients undergoing cardiac surgery. However, transfusion of 4 or more erythrocytes is associated with a higher incidence of clinical complications, in addition to a dose-dependent relationship. Strategies such as early detection of anemia and use of alternative techniques to transfusion in management should be stimulated in the perioperative environment