Risk score elaboration for mediastinitis after coronary artery bypass grafting.

INTRODUCTION: The mediastinitis is a serious postoperative complication of cardiac surgery, with an incidence of 0.4 to 5% and mortality between 14 and 47%. Several models were proposed to assess risk of mediastinitis after cardiac surgery. However, most of these models do not evaluate the postoperative morbidity. OBJECTIVE: This study aims to develop a score risk model to predict the risk of mediastinitis for patients undergoing coronary artery bypass grafting. METHODS: The study sample included data from 2,809 adult patients undergoing coronary artery bypass grafting between January 1996 and December 2007 at Hospital São Lucas -PUCRS. Logistic regression was used to examine the relationship between risk factors and the development of mediastinitis. Data from 1,889 patients were used to develop the model and its performance was evaluated in the remaining data (n=920). The definitive model was created with the data analysis of 2,809 patients. RESULTS: The rate of mediastinitis was 3.3%, with mortality of 26.6%. In the multivariate analysis, five variables remained independent predictors of the outcome: chronic obstructive pulmonary disease, obesity, surgical reintervention, blood transfusion and stable angina class IV or unstable. The area under the ROC curve was 0.72 (95% CI, 0.67-0.78) and P = 0.61. CONCLUSION: The risk score was constructed for use in daily practice to calculate the rate of mediastinitis after coronary artery bypass grafting. The score includes routinely collected variables and is simple to use.

Elaboração de escore de risco para mediastinite pós-cirurgia de revascularização do miocárdio / Risk score elaboration for mediastinitis after coronary artery bypass grafting

INTRODUÇÃO: A mediastinite é uma grave complicação do pós-operatório de cirurgia cardíaca, com prevalência de 0,4 a 5 por cento e mortalidade entre 14 e 47 por cento. Vários modelos foram propostos para avaliar risco de mediastinite após cirurgia cardíaca. OBJETIVO: Desenvolver um modelo de escore de risco para prever mediastinite em pacientes submetidos à cirurgia de revascularização do miocárdio. MÉTODOS: A amostra do estudo inclui dados de 2.809 pacientes adultos que realizaram cirurgia de revascularização do miocárdio, entre janeiro de 1996 e dezembro de 2007, no Hospital São Lucas da PUCRS. Regressão logística foi usada para examinar a relação entre fatores de risco e o desenvolvimento de mediastinite. Dados de 1.889 pacientes foram usados para desenvolver o modelo e seu desempenho foi avaliado nos dados restantes (n=920). O modelo final foi criado com a análise dos dados de 2.809 pacientes. RESULTADOS: O índice de mediastinite foi de 3,3 por cento, com mortalidade de 26,6 por cento. Na análise multivariada, cinco variáveis permaneceram preditores independentes para o desfecho: doença pulmonar obstrutiva crônica, obesidade, reintervenção cirúrgica, politransfusão no pós-operatório e angina estável classe IV ou instável. A área sob a curva ROC foi 0,72 (IC 95 por cento, 0,67-0,78) e P = 0,61. CONCLUSÃO: O escore de risco foi construído para uso na prática diária para calcular o índice de mediastinite após cirurgia de revascularização do miocárdio. O escore inclui variáveis coletadas rotineiramente e de fácil utilização.

INTRODUCTION: The mediastinitis is a serious postoperative complication of cardiac surgery, with an incidence of 0.4 to 5 percent and mortality between 14 and 47 percent. Several models were proposed to assess risk of mediastinitis after cardiac surgery. However, most of these models do not evaluate the postoperative morbidity. OBJECTIVE: This study aims to develop a score risk model to predict the risk of mediastinitis for patients undergoing coronary artery bypass grafting. METHODS: The study sample included data from 2,809 adult patients undergoing coronary artery bypass grafting between January 1996 and December 2007 at Hospital São Lucas -PUCRS. Logistic regression was used to examine the relationship between risk factors and the development of mediastinitis. Data from 1,889 patients were used to develop the model and its performance was evaluated in the remaining data (n=920). The definitive model was created with the data analisys of 2,809 patients. RESULTS: The rate of mediastinitis was 3.3 percent, with mortality of 26.6 percent. In the multivariate analysis, five variables remained independent predictors of the outcome: chronic obstructive pulmonary disease, obesity, surgical reintervention, blood transfusion and stable angina class IV or unstable. The area under the ROC curve was 0.72 (95 percent CI, 0.67-0.78) and P = 0.61. CONCLUSION: The risk score was constructed for use in daily practice to calculate the rate of mediastinitis after coronary artery bypass grafting. The score includes routinely collected variables and is simple to use.

O impacto da obesidade na morbi-mortalidade de pacientes submetidos à cirurgia de revascularização miocárdica / Impact of obesity in morbity and mortality of patients submitted to myocardial revascularization surgery

Objetivos: avaliar se a obesidade pode aumentar a incidência de complicações e mortalidade no pós-operatório de cirurgia de revascularização do miocárdio. Métodos: coorte histórica de 2.445 pacientes submetidos à cirurgia de revascularização do miocárdio entre janeiro de 1996 e dezembro 2006 no Hospital São Lucas da PUCRS. Os casos foram constituídos pelos pacientes obesos, definidos como tendo índice de massa corporal acima de 29kg/m2. As variáveis préoperatórias foram idade, sexo, classe funcional da angina, classe funcional da insuficiência cardíaca, diabetes, acidente vascular encefálico prévio, hipertensão,insuficiência renal, doença pulmonar obstrutiva crônica, tabagismo, uso de balão intra-aórtico, uso de beta-bloqueador e fração de ejeção. No transoperatório foi avaliado o tempo de circulação extracorpórea. As variáveis pós-operatórias incluíram: óbito, mediastinite, acidente vascular encefálico, infecção respiratória, tempo de ventilação mecânica, sepse, uso de drogas vasoativas, síndrome da resposta inflamatória sistêmica, infarto do miocárdio, tromboembolia pulmonar, insuficiência renal aguda, fibrilação atrial, hipertensão, sangramento e tempo de internação hospitalar. A análise estatística foi feita pelo software SPSS 10.5. As variáveis contínuas foram analisadas pelo teste t de Student e as categóricas comparadas pelo teste do qui-quadrado. Foram utilizadas análises univariada e multivariada com cálculo da odds ratio (OR) com intervalo de confiança (IC) de 95% e nível de significância de < 0,05. Resultados: dos 2.445 pacientes incluídos no estudo, 11,5 % eram obesos e 56,2 % eram do sexo masculino. Diabete tipo 1, diabete tipo 2 e hipertensão foram mais prevalentes no grupo dos obesos. Não houve diferença em relação a óbito entre os dois grupos: (10,7 % obesos X 8,6 % não obesos) p = 0,14. Na análise multivariada, a obesidade esteve associada com mediastinite OR=2,7 (IC 95% 1,6-4,5 ), síndrome da resposta inflamatória sistêmica...

Aims: To evaluate if obesity increase the incidence of post-operative complications and mortality after myocardial revascularization surgery. Methods: Hystorical cohort of 2.445 patients who underwent isolated coronary artery bypass grafting surgery etween January 1996 and December 2006 at Hospital São Lucas da PUCRS. The pre-operative variables were: age, sex, functional class of angina (Canadian Heart Association), functional class of heart failure, diabetes, prior cerebral vascular accident (stroke), hypertension, renal dysfunction, chronic obstructive pulmonary disease, smoking, use of Intra-aortic Ballon, use of betablocker, and left ventricular ejection fraction. In the intraoperative, the cardiopulmonary bypass time was evaluated. The postoperative variables included: death, mediastinitis, stroke, respiratory infection, mechanical ventilation time, sepsis, vasoactive drugs, systemic inflammatory response syndrome, myocardial infarction, pulmonary embolism, acute renal disfunction, atrial fibrillation, hypertension, bleeding andlenght of hospital stay. The analysis was performed with statistical software SPSS 10.5, using the Student t test for continuous variables and x square test for categorical variables. Univariate and multivariate analysis were made and the odds ratio (OR) calculated with a 95% confidence interval (CI) and a 0.05 level of significance Results: From the total of 2.445 patients, 11.5% were obese and 56.2% were males. Diabetes, diabetes insulindependent and hypertension were more prevalent in the obese group. There were no differences in relation to death between the two groups: (10.7% in the obese x 8.6% in the non-obese) p = 0.14. In the multivariate analysis obesity was associated with mediastinitis OR=2.7 (95% CI 1.6-4.5), systemic inflammatory response syndrome OR= 2.7 (95% CI 1.8-3.8 ) and pulmonary embolism OR= 2.3 (95% CI 1.3-4.2) Conclusions: In this study obesity...