Effect of body mass index on outcomes after cardiac surgery: is there an obesity paradox?

BACKGROUND: Numerous studies have documented an obesity paradox in which overweight and obese people with cardiovascular disease have a better prognosis compared with patients with normal body mass index (BMI). This study sought to quantify the effect of BMI on clinical outcomes after cardiac surgery and investigate the obesity paradox. METHODS: A concurrent cohort study of 2,440 consecutive patients undergoing cardiac surgery (coronary artery bypass grafting [CABG], valve, or CABG and valve surgery) from January 2004 to December 2008 was carried out. The patients were divided into three groups on the basis of BMI: normal weight (BMI 18.5 to 24.9; n=556; 23%), overweight (BMI 25.0 to 29.9; n=965; 39%), and obese (BMI≥30; n=919; 38%). Multivariable analyses and propensity score matching were used to compare the early and late clinical outcomes among the different BMI groups. RESULTS: Overweight patients had a lower operative mortality (odds ratio, 0.4; 95% confidence interval, 0.2 to 0.9; p=0.031) compared with normal BMI patients. Obese patients had a comparable risk for operative mortality (odds ratio, 0.8; 95% confidence interval, 0.4 to 1.6; p=0.47) compared with normal-weight patients. Actuarial 5-year survival was better for the overweight (hazard ratio, 0.5; 95% confidence interval, 0.4 to 0.8; p=0.002) and comparable for the obese (hazard ratio, 0.9; 95% confidence interval, 0.5 to 1.4; p=0.49) groups compared with the normal-weight patients. CONCLUSIONS: Overweight patients have better early hospital outcomes and improved survival after cardiac surgery compared with normal BMI patients, supporting the obesity paradox.

Aprotinin in cardiac surgery patients: is the risk worth the benefit?

BACKGROUND: Aprotinin is the only Food and Drug Administration-approved agent to reduce haemorrhage related to cardiac surgery and its safety and efficacy has been extensively studied. Our study sought to compare the efficacy, early and late mortality and major morbidity associated with aprotinin compared with e-aminocaproic acid (EACA) in cardiac surgery operations. METHODS: Between January 2002 and December 2006, 2101 patients underwent coronary artery bypass grafting (CABG), valve surgery or CABG and valve surgery in our institution with the use of aprotinin (1898 patients) or EACA (203 patients). Logistic regression and propensity score analysis were used to adjust for imbalances in the patients' preoperative characteristics. The propensity score-adjusted sample included 570 patients who received aprotinin and 114 who received EACA (1-5 matching). RESULTS: Operative mortality was higher in the aprotinin group in univariate (aprotinin 4.3% vs EACA 1%, p=0.023) but not propensity score-adjusted multivariate analysis (4% vs 0.9%, p=0.16). In propensity score-adjusted analysis, aprotinin was also associated with a lower rate of blood transfusion (38.8% vs 50%, p=0.04), a lower rate of haemorrhage-related re-exploration (3.7% vs 7.9%, p=0.04) and a higher risk of in-hospital cardiac arrest (3.7% vs 0%, p=0.03) and a marginally but not statistically significantly higher risk of acute renal failure (6.8% vs 2.6%, p=0.09). In Cox proportional hazards regression analysis, the risk of late death was higher in the aprotinin compared to EACA group (hazard ratio=4.33, 95% confidence interval (CI)=1.60-11.67, p=0.004). CONCLUSION: Aprotinin decreases the rate of postoperative blood transfusion and haemorrhage-related re-exploration, but increases the risk of in-hospital cardiac arrest and late mortality after cardiac surgery when compared to EACA. Cumulative evidence suggests that the risk associated with aprotinin may not be worth the haemostatic benefit.

Quality improvement program increases early tracheal extubation rate and decreases pulmonary complications and resource utilization after cardiac surgery.

BACKGROUND: Early tracheal extubation is a common goal after cardiac surgery and may improve postoperative outcomes. Our study evaluates the impact of a quality improvement program (QIP) on early extubation, pulmonary complications, and resource utilization after cardiac surgery. METHODS: Between 2002 and 2006, 980 patients underwent early tracheal extubation (<6 hours after surgery) and 1231 had conventional extubation (> 6 hours after surgery, conventional group). Outcomes compared between the two groups included: (1) pneumonia, (2) sepsis, (3) intensive care unit (ICU) length of stay, (4) hospital length of stay, (5) ICU readmission, and (6) reintubation. Logistic regression analysis and propensity score adjustment were used to adjust for imbalances in the patients' preoperative characteristics. RESULTS: Early extubation rates were significantly increased with QIP (QIP 53% vs. Non-QIP 38%, p = 0.01). Early extubation was associated with a lower rate of (1) pneumonia (odds ratio [OR]= 0.35, 95% confidence intervals [CI]= 0.22-0.55, p <0.001), (2) sepsis (OR = 0.38, CI = 0.20-0.74, p <0.004), (3) prolonged ICU length of stay (OR = 0.42, CI = 0.35-0.50, p <0.001), (4) hospital length of stay (OR = 0.37, CI = 0.29-0.47, p <0.001), (5) ICU readmission (OR = 0.55, CI = 0.39-0.78, p <0.001), and (6) reintubation (OR = 0.53, CI = 0.34-0.81, p <0.003) both in multivariable logistic regression analysis and propensity score adjustment. CONCLUSIONS: QIP and early tracheal extubation reduce pulmonary complications and resource utilization after cardiac surgery.

Continuous quality improvement program and major morbidity after cardiac surgery.

The aim of this study was to investigate how a continuous quality improvement (CQI) program affected major morbidity and postoperative outcomes after cardiac surgery. Patients were divided into 2 groups: those who underwent surgery (coronary artery bypass grafting, isolated valve surgery, or coronary artery bypass grafting and valve surgery) after the establishment of a CQI program (from January 2005 to December 2006, n = 922) and those who underwent surgery beforehand (from January 2002 to December 2003, n = 1,289). Patients who had surgery in 2004, when the system and processes were reengineered, were not included in the analysis. Outcomes compared between the 2 groups included (1) acute renal failure, (2) stroke, (3) sepsis, (4) hemorrhage-related reexploration, (5) cardiac tamponade, (6) mediastinitis, and (7) prolonged length of stay. Logistic regression analysis and propensity score adjustment were used to adjust for imbalances in the patients' preoperative characteristics. After propensity score adjustment, CQI was found to decrease the rate of sepsis (odds ratio [OR] 0.5, 95% confidence interval [CI] 0.3 to 0.9, p = 0.02) and cardiac tamponade (OR 0.2, 95% CI 0.04 to 0.8, p = 0.02) but to only marginally decrease the rate of acute renal failure (OR 0.7, 95% CI 0.5 to 1.0, p = 0.07). CQI did not emerge as an independent risk factor for hemorrhage-related reexploration, prolonged length of stay, mediastinitis, or stroke in either multivariate logistic regression analysis or propensity score adjustment. In conclusion, the systematic implementation of a CQI program and the application of multidisciplinary protocols decrease sepsis and cardiac tamponade after cardiac surgery.

Quality improvement program decreases mortality after cardiac surgery.

OBJECTIVE: This study investigated the effects of a quality improvement program and goal-oriented, multidisciplinary protocols on mortality after cardiac surgery. METHODS: Patients were divided into two groups: those undergoing surgery (coronary artery bypass grafting, isolated valve surgery, or coronary artery bypass grafting and valve surgery) after establishment of the multidisciplinary quality improvement program (January 2005-December 2006, n = 922) and those undergoing surgery before institution of the program (January 2002-December 2003, n = 1289). Logistic regression and propensity score analysis were used to adjust for imbalances in patients' preoperative characteristics. RESULTS: Operative mortality was lower in the quality improvement group (2.6% vs 5.0%, P < .01). Unadjusted odds ratio was 0.5 (95% confidence interval 0.3-0.8, P < .01); propensity score-adjusted odds ratio was 0.6 (95% confidence interval 0.4-0.99, P = .04). In multivariable analysis, diabetes (P < .01), chronic renal insufficiency (P = .05), previous cardiovascular operation (P = .04), congestive heart failure (P < .01), unstable angina (P < .01), age older than 75 years (P < .01), prolonged pump time (P < .01), and prolonged operation (P = .05) emerged as independent predictors of higher mortality after cardiac surgery, whereas quality improvement program (P < .01) and male sex (P = .03) were associated with lower mortality. Mortality decline was less pronounced in patients with than without diabetes (P = .04). CONCLUSION: Application of goal-directed, multidisciplinary protocols and a quality improvement program were associated with lower mortality after cardiac surgery. This decline was less prominent in patients with diabetes, and focused quality improvement protocols may be required for this subset of patients.