title: The impact of body mass index on short- and long-term outcomes inpatients undergoing coronary revascularization. Insights from the bypass angioplasty revascularization investigation (BARI). The Influence of Body Mass Index on Outcomes in Patients Undergoing Cardiac Surgery: Does the Obesity Paradox Really Exist? Relationship of body mass index with outcomes after coronary artery bypass graft surgery. Effects of intensified lifestyle modification on the need for further revascularization after coronary angioplasty Obesity paradox in coronary artery bypass grafting: myth or reality?
abstract: OBJECTIVES We sought to investigate the impact of body mass index ( BMI ) on short- and long-term outcomes after initial revascularization with percutaneous transluminal coronary angioplasty ( PTCA ) or coronary artery bypass graft surgery ( CABG ) .  BACKGROUND Equivocal results exist on the impact of BMI on the risk of in-hospital complications after PTCA or CABG , and no long-term mortality data exist from a large series of revascularized patients . METHODS From the r and omized series and observational registry of the Bypass Angioplasty Revascularization Investigation ( BARI ) , 2,108 patients who had PTCA and 1,526 patients who had CABG were evaluated by taking their BMI at study entry . They were classified as follows : low ( < 20 kg/m(2 ) ) , normal ( 20 to 24.9 kg/m(2 ) ) , overweight ( 25 to 29.9 kg/m(2 ) ) , class I obese ( 30 to 34.9 kg/m(2 ) ) and class II/III obese ( greater-than-or-equal 35 kg/m(2 ) ) . In-hospital complications and short- and long-term mortalities were compared between levels of BMI within each mode of initial revascularization . RESULTS Among patients who had PTCA , each unit increase in BMI was associated with a 5.5 % lower adjusted risk of a major in-hospital event ( death , myocardial infa rct ion , stroke , coma ) ; among patients who had CABG , no difference in the in-hospital outcome was observed according to BMI . In contrast , BMI was not associated with five-year mortality in the PTCA group ; among the CABG group , adjusted relative risks of five-year cardiac mortality according to levels of BMI were 0.0 ( low ) , 1.0 ( normal ) , 2.02 ( overweight ) , 3.16 ( class I obese ) and 4.85 ( class II/III obese ) ( linear p < 0.001 ) . CONCLUSIONS Body mass index appears to have a differential impact on short- and long-term outcomes after coronary revascularization . These results underscore the need for further research to identify factors responsible for the apparent short-term protective effect of a higher BMI in patients undergoing PTCA and to study the impact of weight reduction on the long-term survival of obese patients undergoing CABG Purpose Obesity influences risk stratification in cardiac surgery in everyday practice . However , some studies have reported better outcomes in patients with a high body mass index ( BMI ): this is known as the obesity paradox . The aim of this study was to quantify the effect of diverse degrees of high BMI on clinical outcomes after cardiac surgery , and to assess the existence of an obesity paradox in our patients . Methods A total of 2,499 consecutive patients requiring all types of cardiac surgery with cardiopulmonary bypass between January 2004 and February 2009 were prospect ively studied at our institution . Patients were divided into four groups based on BMI : normal weight ( 18.5–24.9 kg∙m−2 ; n = 523 ; 21.4 % ) , overweight ( 25–29.9kg∙m−2 ; n = 1150 ; 47 % ) , obese ( ≥30–≤34.9kg∙m−2 ; n = 624 ; 25.5 % ) and morbidly obese ( ≥35kg∙m−2 ; n = 152 ; 6.2 % ) . Follow-up was performed in 2,379 patients during the first year . Results After adjusting for confounding factors , patients with higher BMI presented worse oxygenation and better nutritional status , reflected by lower PaO2/FiO2 at 24h and higher albumin levels 48h after admission respectively . Obese patients showed a higher risk for Perioperative Myocardial Infa rct ion ( OR : 1.768 ; 95 % CI : 1.035–3.022 ; p = 0.037 ) and septicaemia ( OR : 1.489 ; 95 % CI : 1.282–1.997 ; p = 0.005 ) . In-hospital mortality was 4.8 % ( n = 118 ) and 1-year mortality was 10.1 % ( n = 252 ) . No differences were found regarding in-hospital mortality between BMI groups . The overweight group showed better 1-year survival than normal weight patients ( 91.2 % vs. 87.6 % ; Log Rank : p = 0.029 . HR : 1.496 ; 95 % CI : 1.062–2.108 ; p = 0.021 ) . Conclusions In our population , obesity increases Perioperative Myocardial Infa rct ion and septicaemia after cardiac surgery , but does not influence in-hospital mortality . Although we found better 1-year survival in overweight patients , our results do not support any protective effect of obesity in patients undergoing cardiac surgery BACKGROUND A debate exists whether obesity is a risk factor for operative mortality after  coronary artery bypass graft surgery ( CABG ) . The contradictory findings in the literature may largely be attributable to the variety of method ological approaches used to model the association between body mass index ( BMI ) and post-CABG outcomes . This study aims to investigate this association , and to uncover possible explanations for the lack of consensus across prior studies . METHODS Data were prospect ively collected on 80,792 patients who underwent a CABG procedure during a 14-year period at the 45 Department of Veterans Affairs cardiac surgery programs .  Generalized additive models were used to estimate the relationship of BMI and outcomes after a CABG procedure . RESULTS We found that the relationship of BMI with post-CABG mortality and morbidity is U-shaped with the minimum risk located around a BMI of 30 kg/m2 , indicating that patients classified as overweight have the lowest risk , and those in the lower end of the obese range do not have seriously elevated risk . This U-shape relationship is significantly nonlinear and robust to adjustment for other risk factors . CONCLUSIONS This study demonstrates that BMI is an independent predictor of mortality and morbidity after CABG surgery . Previous studies that model BMI linearly or as categories can not accurately capture this U-shaped relationship and are unlikely to find a significant contribution by including BMI . Further research is needed to determine the mechanisms of risk for patients with low and high BMI and whether interventions to modify BMI may improve patient outcomes In patients with coronary artery disease ( CAD ) , a rate of restenosis as high as 50 % is observed after percutaneous transluminal coronary angioplasty ( PTCA ) . Frequently , this results in further revascularization procedures . Lifestyle intervention has been shown to slow the progression of CAD and to reduce cardiovascular events after myocardial infa rct ion . However , no information exists whether such treatment influences the rate of restenosis in patients with CAD . The present study was performed to investigate the effects of an intensified lifestyle intervention on the need for further revascularization procedures in patients with established CAD after successful PTCA OBJECTIVE A high body mass index has been suggested to be protective in patients with coronary artery disease and in those undergoing coronary artery bypass grafting ( CABG ) .  However , these conflicting results might be related to the different risk profiles among the various body mass index categories . We sought to clarify the effect of varying degrees of excessive body weight on hard clinical outcomes in patients undergoing CABG .  METHODS A retrospective analysis of prospect ively collected data was conducted to investigate the effect of a high body mass index on early and late mortality after  first-time isolated CABG . Propensity score matching was used to adjust for confounding factors . RESULTS The study sample consisted of 3269 normal weight , 6662 overweight , 3821 obese , and 211 morbidly obese patients . After matching , early mortality was not affected by overweight ( mean difference , 0.7 % ; 95 % confidence interval [ CI ] , -0.2 % to 1.5 % ) , obesity ( mean difference , 0.5 % ; 95 % CI , -0.7 % to 1.7 % ) , and morbid obesity ( mean difference , 1.6 % ; 95 % CI , -1.0 % to 1.0 % ) , regardless of the patients ' risk profile according to the European system for cardiac operative risk evaluation . Overweight status was not protective for late death ( hazard ratio , 1.05 ; 95 % CI , 0.9 - 1.08 ; P = .4 ) . Compared with normal weight patients , both obese and morbidly obese patients had a higher risk of late death ( hazard ratio , 1.22 ; 95 % CI , 1.07 - 2.66 ; P = .006 for obese patients ; hazard ratio , 1.36 ; 95 % CI , 0.74 - 2.49 ; P = .3 for morbidly obese patients ) . CONCLUSIONS Obesity did not increase operative mortality , but it was associated with reduced late survival in patients undergoing primary isolated CABG . Our results raise concerns in supporting any protective effect of obesity in cardiovascular disease , specifically in patients undergoing surgical myocardial revascularization
target: Conclusions : Obesity is associated with lower risks after cardiac surgery , with consistent effects noted in multiple analyses attempting to address residual confounding and reverse causation
background: Background : In an apparent paradox , morbidity and mortality are lower in obese patients undergoing cardiac surgery  , although the nature of this association is unclear .
  We sought to determine whether the obesity paradox observed in cardiac surgery is attributable to reverse epidemiology , bias , or confounding .