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Objective To determine which of four proposed risk scores best predicts immediate outcome of cardiac surgery. Design Observational cohort study. Setting Sir Charles Gairdner Hospital (a university teaching hospital), Perth, Western Australia, 18 March 1993 to 5 March 1996. Subjects 927 consecutive patients undergoing surgery for coronary artery disease. Outcome measures Patient risk scores (by methods of Parsonnet et al., Higgins et al., Tremblay et al. and Tu et al.); in‐hospital mortality; postoperative hospital stay >14 days; receiver operating characteristic (ROC) curves comparing sensitivity and specificity in predicting adverse outcomes for each risk score. Results In‐hospital mortality rate was 3.5% and mean postoperative hospital stay was 10.7 days. The four scores had similar predictive abilities, with mean areas under the ROC curves (95% confidence intervals) for mortality and postoperative stay >14 days, respectively: 0.70 (0.62‐0.78) and 0.70 (0.65‐0.75) for the Parsonnet score; 0.68 (0.59‐0.77) and 0.70 (0.64‐0.75) for the Higgins score; 0.68 (0.59‐0.77) and 0.67 (0.62‐0.73) for the Tremblay score; and 0.68 (0.60‐0.76) and 0.69 (0.64‐0.75) for the Tu score. Conclusion Any of the scores may be used to estimate perioperative risk and to compare outcome between coronary surgery units, but none has sufficient specificity and sensitivity to identify specific individuals who will experience an adverse outcome. Further development of risk assessment is needed before adverse outcome can be accurately predicted in cardiac surgical patients.

Background: It has been suggested that blood transfusion has an adverse effect on long-term health, mainly through immune modulation and tumor promotion. To further assess this concern, the authors have performed a prospective observational study with the hypothesis that after taking perioperative risk factors relevant to long-term survival into account, patients undergoing coronary artery surgery who receive a perioperative allogeneic blood transfusion have worse long-term survival than those who do not.Methods: The health outcomes of 1,841 consecutive subjects who had isolated nonemergency first-time coronary artery surgery and who survived more than 60 days after surgery were determined by record linkage. The association between length of survival, blood products transfused, and risk factors for longterm survival at entry to the study were determined by Cox proportional hazards regression.Results: A total of 1,062 subjects were transfused. Of these, 266 subjects died during a mean follow-up of 8.1 yr. Of subjects who were transfused, 27% had a new malignant condition recorded on the death certificate, compared with 43% who were not transfused. Older age, cerebrovascular disease, use of a mammary graft, chronic pulmonary disease, renal dysfunction, reduced left ventricular function, and preoperative anemia were predictive of reduced long-term survival. There was no association between transfusion of blood products and longterm survival.Conclusions: Patients who have undergone coronary artery surgery and who have received moderate amounts of blood as part of responsible and conservative management should be reassured that they are unlikely to experience a reduction in long-term survival.

In an observational study using heparinase-modified thrombelastography, we investigated the percentage of elective cardiothoracic surgical patients receiving low-dose unfractionated heparin (5000 IU 12 hourly subcutaneously) who had a demonstrable systemic heparin effect. Blood samples were obtained at induction from 40 adult elective cardiothoracic surgical patients who had received 5000 IU unfractionated heparin subcutaneously within six hours. Simultaneous kaolin and heparinase-modified thrombelastographies were run on all samples. Fourteen patients (35%; 95% CI: 20 to 50%) had a demonstrable heparin effect(defined as a kaolin thrombelastography R time >25% longer than the heparinase-modified control). Their mean±SD kaolin thrombelastography R time was 13.6±5.9 minutes (normal range 4 to 8 minutes) vs. 7.1±2.0 minutes for the heparinase-modified controls. In 10 patients the thrombelastography R times were >50% longer and in four patients >100% longer, than their respective heparinase-modified controls. In a post hoc analysis, there was little correlation between the extent of the prolongation and patient age (r=0.02), weight (r=-0.31), preoperative creatinine (r=-0.17), or time since administration of heparin (r=0.14). These results indicate that about one third of patients who have received low-dose unfractionated heparin subcutaneously within six hours have a demonstrable heparin effect. The potential for this effect should be considered if central neural blockade is planned.