The Influence of Body Mass Index on Outcomes in Patients Undergoing Cardiac Surgery: Does the Obesity Paradox Really Exist? Body mass index and mortality in acutely decompensated heart failure across the world: a global obesity paradox. Obesity paradox in coronary artery bypass grafting: myth or reality? Cardiovascular risk in relation to body mass index and use of evidence-based preventive medications in patients with or at risk of atherothrombosis. Is obesity a predictor of mortality, morbidity and readmission after cardiac surgery?
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 OBJECTIVES This study sought to define the relationship between  body mass index ( BMI )  and mortality in heart failure ( HF ) across the world and to identify specific groups in whom BMI may differentially mediate risk . BACKGROUND Obesity is associated with incident HF , but it is paradoxically associated with better prognosis during chronic HF . METHODS We studied 6,142 patients with acute decompensated HF from 12 prospect i ve observational cohorts followed-up across 4 continents . Primary outcome was all-cause mortality . Cox proportional hazards models and net reclassification index described associations of BMI with all-cause mortality . RESULTS Normal-weight patients ( BMI 18.5 to 25 kg/m(2 ) ) were older with more advanced HF and lower cardiometabolic risk . Despite worldwide heterogeneity in clinical features across obesity categories , a higher BMI remained associated with decreased 30-day and 1-year mortality ( 11 % decrease at 30 days ; 9 % decrease at 1 year per 5 kg/m(2 ) ; p < 0.05 ) , after adjustment for clinical risk . The BMI obtained at index admission provided effective 1-year risk reclassification beyond current markers of clinical risk ( net reclassification index 0.119 , p < 0.001 ) . Notably , the " protective " association of BMI with mortality was confined to persons with older age ( > 75 years ; hazard ratio [ HR ] : 0.82 ; p = 0.006 ) , decreased cardiac function ( ejection fraction < 50 % ; HR : 0.85 ; p < 0.001 ) , no diabetes ( HR : 0.86 ; p < 0.001 ) , and de novo HF ( HR : 0.89 ; p = 0.004 ) . CONCLUSIONS A lower BMI is associated with age , disease severity , and a higher risk of death in acute decompensated HF . The " obesity paradox " is confined to older persons , with decreased cardiac function , less cardiometabolic illness , and recent-onset HF , suggesting that aging , HF severity/chronicity , and metabolism may explain the obesity paradox 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 AIM Explore the relation between body mass index ( BMI ) and cardiovascular disease , and the influence of optimal medical therapy ( OMT ) on this relationship . METHODS AND RESULTS Patients from the REACH cohort , an international , prospect i ve cohort of patients with or at high risk of atherosclerosis with documentation of potential confounders , including treatments and risk factors , were followed up to 4 years ( n = 54 285 ) . Patients were categorized according to baseline BMI ( ranging from underweight to Grade III obesity ) . Optimal medical therapy was defined as the use of the four cardioprotective medication classes ( statins , ACE inhibitors/angiotensin II receptor blockers , β-blockers , and antiplatelet agents ) . The main outcomes were all-cause mortality , cardiovascular ( CV ) mortality , and CV events . In primary and secondary prevention , a reverse J-shaped curve best described the relationship between BMI categories and the incidence of the various outcomes . In secondary prevention , the highest adjusted risks were observed for underweight patients ( 1.97 , P < 0.01 , and 1.29 , P = 0.03 , for CV mortality and CV events ) and the lowest HRs were observed , respectively , in Grade II and Grade III obese patients ( 0.73 , P < 0.01 and 0.80 , P < 0.01 ) . The proportion of patients on OMT increased with BMI from 10.1 to 36 % ( P < 0.001 ) . The apparent CV protection conferred by obesity persisted in patients receiving OMT . CONCLUSION An obesity paradox was observed in both primary and secondary CV prevention patients . The intensity of use of evidence -based preventive medications does not account for the paradoxical CV protection associated with obesity . At extremes of BMI , further interventions beyond OMT may be needed to reduce CV risk INTRODUCTION Obesity has been described as a risk factor for the development of coronary artery disease , but it has not been determined whether obesity is associated with adverse outcomes after cardiac surgery . Therefore , we analyzed a large cohort of patients who had undergone cardiac surgery to determine whether obesity is a predictor of mortality , morbidity or early readmission to hospital . METHODS At the London Health Sciences Centre , an academic tertiary care centre , we prospect ively entered data from the cardiac surgical data base from July 1999 to April 2002 . We collected data on 1310 consecutive , unselected patients who underwent cardiac surgery during that time . We assessed the degree of obesity using the body mass index ( BMI ) , and we prospect ively documented the occurrence of 10 major complications after surgery . They included stroke , reoperation for bleeding , life-threatening cardiac arrest or arrhythmia , new renal failure requiring dialysis , septicemia , mediastinitis , sternal dehiscence , respiratory failure , postoperative myocardial infa rct ion and low cardiac output necessitating intra-aortic balloon pump use . Univariable and multivariable analyses were conducted to determine the factors associated with and predictive of postoperative death and major complications . RESULTS An increased BMI did not increase the risk of early postoperative death . Furthermore , increased BMI was not a predictor of a patient experiencing any of the major complications , except sternal dehiscence . An increased BMI was associated with a higher likelihood of readmission to hospital within 30 days of discharge . CONCLUSION Obesity was not associated with adverse outcomes after cardiac operations , aside from the increased risks of sternal dehiscence and early hospital readmission
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 : 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 .