Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery: A Nationwide Study With a Systematic Review and Meta-Analysis

Giovanni Mariscalco (Corresponding Author), Marcin J. Wozniak, Alan G. Dawson, Giuseppe F. Serraino, Richard Porter, Mintu Nath, Catherine Klersy, Tracy Kumar, Gavin J. Murphy

Research output: Contribution to journalReview article

56 Citations (Scopus)

Abstract

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.

METHODS: Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.

RESULTS: A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.

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.

Original languageEnglish
Pages (from-to)850-863
Number of pages14
JournalCirculation
Volume135
Issue number9
Early online date28 Dec 2016
DOIs
Publication statusPublished - 28 Feb 2017

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Thoracic Surgery
Meta-Analysis
Body Mass Index
Mortality
Obesity
Odds Ratio
Confidence Intervals
Cohort Studies
Cardiac Surgical Procedures
Low Cardiac Output
Renal Replacement Therapy
Thinness
Wound Infection
Chronic Renal Insufficiency
MEDLINE
Causality
Lung Diseases
Libraries
Registries
Heart Diseases

Keywords

  • adult
  • cardiac surgical procedures
  • mobidity
  • mortality
  • obesity

Cite this

Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery : A Nationwide Study With a Systematic Review and Meta-Analysis. / Mariscalco, Giovanni (Corresponding Author); Wozniak, Marcin J.; Dawson, Alan G.; Serraino, Giuseppe F.; Porter, Richard; Nath, Mintu; Klersy, Catherine; Kumar, Tracy; Murphy, Gavin J.

In: Circulation, Vol. 135, No. 9, 28.02.2017, p. 850-863.

Research output: Contribution to journalReview article

Mariscalco, G, Wozniak, MJ, Dawson, AG, Serraino, GF, Porter, R, Nath, M, Klersy, C, Kumar, T & Murphy, GJ 2017, 'Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery: A Nationwide Study With a Systematic Review and Meta-Analysis', Circulation, vol. 135, no. 9, pp. 850-863. https://doi.org/10.1161/CIRCULATIONAHA.116.022840
Mariscalco, Giovanni ; Wozniak, Marcin J. ; Dawson, Alan G. ; Serraino, Giuseppe F. ; Porter, Richard ; Nath, Mintu ; Klersy, Catherine ; Kumar, Tracy ; Murphy, Gavin J. / Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery : A Nationwide Study With a Systematic Review and Meta-Analysis. In: Circulation. 2017 ; Vol. 135, No. 9. pp. 850-863.
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note = "ACKNOWLEDGMENTS The authors thank Dr Francesco Zaccardi for critical reading of the manuscript and for statistical advice. SOURCES OF FUNDING This study was supported by British Heart Foundation (RG/13/6/29947) and the National Institute for Health Research Leicester Biomedical Research Unit in Cardiovascular Medicine. Drs Murphy and Wozniak are supported by the British Heart Foundation (CH/12/1/29419).",
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T2 - A Nationwide Study With a Systematic Review and Meta-Analysis

AU - Mariscalco, Giovanni

AU - Wozniak, Marcin J.

AU - Dawson, Alan G.

AU - Serraino, Giuseppe F.

AU - Porter, Richard

AU - Nath, Mintu

AU - Klersy, Catherine

AU - Kumar, Tracy

AU - Murphy, Gavin J.

N1 - ACKNOWLEDGMENTS The authors thank Dr Francesco Zaccardi for critical reading of the manuscript and for statistical advice. SOURCES OF FUNDING This study was supported by British Heart Foundation (RG/13/6/29947) and the National Institute for Health Research Leicester Biomedical Research Unit in Cardiovascular Medicine. Drs Murphy and Wozniak are supported by the British Heart Foundation (CH/12/1/29419).

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Y1 - 2017/2/28

N2 - 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.METHODS: Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.RESULTS: A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.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.

AB - 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.METHODS: Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.RESULTS: A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.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.

KW - adult

KW - cardiac surgical procedures

KW - mobidity

KW - mortality

KW - obesity

UR - http://hdl.handle.net/2381/42682

U2 - 10.1161/CIRCULATIONAHA.116.022840

DO - 10.1161/CIRCULATIONAHA.116.022840

M3 - Review article

C2 - 28034901

VL - 135

SP - 850

EP - 863

JO - Circulation

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SN - 0009-7322

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