Early mortality from off-pump and on-pump coronary bypass surgery in Canada: a comparison of the STS and the EuroSCORE risk prediction algorithms.

OBJECTIVE: Early mortality from off-pump and on-pump coronary artery bypass graft (CABG) surgery was assessed and compared with two widely used risk algorithms for CABG: The Society of Thoracic Surgeons (STS) and the European System for Cardiac Operative Risk Evaluation (EuroSCORE). METHOD: From March 12, 2001, to December 31, 2002, 1657 consecutive patients were treated with off-pump CABG and 1693 consecutive patients were treated with on-pump CABG. The predicted risk of mortality scores for the STS and EuroSCORE models were calculated. The predictive accuracy for early mortality was assessed by comparing the observed and expected mortalities for equal-sized quantiles of risk using the Hosmer-Lemeshow goodness-of-fit test. The discriminatory power of the models was evaluated by calculating the area under the receiver operating characteristic (ROC) curves. RESULTS: The observed postoperative mortality was 1.8% (95% CI 1.3% to 2.4%) for off-pump CABG and 1.5% (95% CI 1.1% to 2.1%) for on-pump CABG. For both on-pump and off-pump CABG surgery, the Hosmer-Lemeshow goodness-of-fit test indicated good accuracy. The area under the ROC curve was 0.81 (95% CI 0.73 to 0.90) for the STS and 0.79 (95% CI 0.71 to 0.88) for EuroSCORE in off-pump CABG (P=0.567). The area under the ROC curve was 0.82 (95% CI 0.73 to 0.91) for STS and 0.81 (95% CI 0.71 to 0.90) for EuroSCORE in on-pump CABG (P=0.616). The STS-predicted risk of stroke, prolonged ventilation and renal failure were similar to the observed data, with relatively good discriminatory powers for both off-pump and on-pump CABG. CONCLUSION: Both the STS and EuroSCORE risk algorithms are good predictors of early mortality from off-pump or on-pump CABG surgery. However, the generalizability of these results in the Canadian context would require a broader sampling of Canadian centres, including ones that provide both on-pump and off-pump CABG.

A cost comparison of off-pump CABG versus on-pump CABG at one-year: The Canadian off-pump CABG registry.

BACKGROUND: Evidence suggests that off-pump coronary artery bypass graft surgery (CABG) is as safe and effective as on-pump CABG, and the cost of initial hospitalization for off-pump CABG is less expensive than on-pump CABG. However, it is uncertain whether the cost savings are sustained over a longer period of time. OBJECTIVE: To assess in-hospital and one-year direct medical costs of off-pump CABG versus on-pump CABG in the context of the Canadian health care system. METHODS AND RESULTS: From March 2001 to December 2002, 1657 consecutive patients enrolled in the Canadian Off-Pump CABG Registry were compared with 1693 consecutive on-pump patients from Hamilton Health Sciences CABG database. At one year, patients of both groups were followed by telephone interview. An economic analysis was conducted from the perspective of the Ontario Ministry of Health and Long-Term Care, and the data analysis was based on propensity score-matched registry patients (1233 pairs) to ensure the comparability of the two study groups. Clinical event and resource use information was collected from all patients. Unit costs from the Hamilton Health Sciences case-costing system were used to estimate hospital costs; all costs were reported in 2003 Canadian dollars. Sensitivity analyses were performed to account for uncertainties. The cost of initial hospitalization for off-pump CABG was significantly less than on-pump CABG (11,744 dollars versus 13,720 dollars, P < 0.001). Although follow-up costs were similar between the groups, the one-year total cost per patient for off-pump CABG remained significantly less than on-pump CABG (12,063 dollars versus 14,141 dollars, P < 0.001). CONCLUSION: Off-pump CABG offers significant savings during initial hospitalization that are also sustained after one year.

The Canadian off-pump coronary artery bypass graft registry: a one-year prospective comparison with on-pump coronary artery bypass grafting.

BACKGROUND: The authors sought to examine in-hospital and one-year outcomes of off-pump coronary artery bypass grafting (CABG) and to determine the subgroups of patients most likely to benefit from the off-pump procedure in a regular surgical practice. METHODS: From March 2001 to December 2002, 1657 consecutive patients were treated with off-pump CABG and 1693 consecutive patients were treated with on-pump CABG. Propensity score modelling was performed to control for treatment and selection bias. A propensity-matched analysis was performed to identify factors associated with survival benefit from the off-pump procedure. RESULTS: The mortality was similar postoperatively and at one year after surgery. The rate of stroke was decreased in the off-pump group postoperatively (OR=0.49, 95% CI 0.23 to 1.06) and significantly at one year after surgery (OR=0.49, 95% CI 0.27 to 0.90). A significant reduction in acute renal dialysis and a significant increase in myocardial infarction rates were seen in off-pump patients during the initial hospitalization but these differences disappeared during the follow-up period. The number of grafts completed was significantly lower in off-pump CABG than in on-pump CABG (2.62+/-1.00 versus 3.36+/-0.92, respectively; P<0.001). Hospital length of stay and the percentage of patients who required mechanical ventilation were significantly lower in the off-pump group than in the on-pump group. At one year after surgery, the adjusted rate of coronary angiogram and revascularization was similar between the two groups, and the adjusted rate of self-reported angina and memory status was significantly better in the off-pump CABG group. Almost all subgroups of patients had a neutral effect or a survival benefit with the off-pump technique. CONCLUSIONS: The results from a Canada-wide multicentre registry showed the safety and effectiveness of off-pump CABG in most subgroups of patients in a regular surgical practice.

The effect of oxygenator membranes on blood: a comparison of two oxygenators in open-heart surgery.

Open-heart surgery (OHS) requires cardiopulmonary bypass (CPB) in most patients. Membrane oxygenators are a critical component of the CPB system. Despite advancements in CPB technology, injury to blood components during CPB still occurs and may result in complications after surgery. The purpose of the present study was to evaluate the performance of the Medtronic Affinity NT with Trillium coating and the Cobe Optima XP oxygenators and compare their influence on blood components. Two hundred and fifty-six male and female patients scheduled for urgent or elective cardiac surgery with CPB were randomly assigned to either the Affinity NT or the Optima XP oxygenators. Outcomes included platelets, hemoglobin, leukocyte counts, and O2 transfer, measured preoperatively and at 15, 45 and 75 min of CPB time. Blood loss was measured at six and 12 hours postoperatively. A modified intention-to-treat analysis was conducted. The two groups were similar for age, sex, height, weight, body surface area, and blood components at baseline. There were no differences between the Affinity NT and Optima XP for any outcome measure, although a significant change with time was seen in platelets, hemoglobin, hematocrit and leukocytes, as well as O2 transfer for both groups (p < 0.001). The Affinity NT oxygenator had a significantly lower difference in pressure across the membrane (p < 0.001) compared with the Optima XP. In conclusion, the two oxygenators performed similarly with respect to their impact on blood components, O2 transfer, and blood loss postoperatively during OHS with CPB. The Affinity NT had the smaller transmembrane pressure drop of the two.

Economic evaluation of the MEDENOX trial: a Canadian perspective. Medical Patients with Enoxaparin.

OBJECTIVE: To perform an economic evaluation of the Prophylaxis in Medical Patients with Enoxaparin (MEDENOX) trial from a Canadian perspective. METHOD: Using a decision tree model, cost effectiveness analysis was carried out to compare the costs and consequences of thromboprophylaxis using enoxaparin 40 mg with placebo in tertiary and community settings. From a third party payer's perspective, the model calculated the expected rate of symptomatic venous thromboembolism (VTE), and the total expected cost of prophylaxis and VTE management, including inpatient and outpatient treatment, professional fees and long term therapy. Data were derived directly from the MEDENOX trial. Costs are direct medical costs in year 2000 Canadian dollars. RESULTS: In a tertiary setting in which the estimated inpatient to outpatient deep vein thrombosis treatment ratio was 10%:90%, the total expected cost per patient was 64 dollars in the enoxaparin group and 62 dollars in the placebo group. The expected symptomatic VTE rates were 0.8% and 3.1% in the enoxaparin and placebo groups, respectively. The incremental cost effectiveness of enoxaparin 40 mg versus placebo was 87 dollars/VTE avoided. In a community hospital setting (with a 50%:50% inpatient to outpatient deep vein thrombosis treatment ratio), the total expected cost per patient was 68 dollars in the enoxaparin group compared with 72 dollars in the placebo group, indicating that prophylaxis with enoxaparin 40 mg was cost saving. The model was sensitive to the inpatient to outpatient ratio. However, within each setting, the results were not sensitive to changes in key variables. CONCLUSION: For patients hospitalized for acute respiratory failure, congestive heart failure or acute infectious disease and who are at moderate risk of developing VTE, thromboprophylaxis with enoxaparin 40 mg daily is a cost effective strategy in both tertiary and community settings.