Elsevier

The Lancet

Volume 368, Issue 9536, 19–25 August 2006, Pages 666-678
The Lancet

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Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies

https://doi.org/10.1016/S0140-6736(06)69251-9Get rights and content

Summary

Background

Studies of the association between obesity, and total mortality and cardiovascular events in patients with coronary artery disease (CAD) have shown contradictory results. We undertook a systematic review to determine the extent and nature of this association.

Methods

We selected cohort studies that provided risk estimates for total mortality, with or without cardiovascular events, on the basis of bodyweight or obesity measures in patients with CAD, and with at least 6 months' follow-up. CAD was defined as history of percutaneous coronary intervention, coronary artery bypass graft, or myocardial infarction. We obtained risk estimates for five predetermined bodyweight groups: low, normal weight (reference), overweight, obese, and severely obese.

Findings

We found 40 studies with 250,152 patients that had a mean follow-up of 3·8 years. Patients with a low body-mass index (BMI) (ie, <20) had an increased relative risk (RR) for total mortality (RR=1·37 [95% CI 1·32–1·43), and cardiovascular mortality (1·45 [1·16–1·81]), overweight (BMI 25–29.9) had the lowest risk for total mortality (0·87 [0·81–0·94]) and cardiovascular mortality (0·88 [0·75–1·02]) compared with those for people with a normal BMI. Obese patients (BMI 30–35) had no increased risk for total mortality (0·93 [0·85–1·03]) or cardiovascular mortality (0·97 [0·82–1·15]). Patients with severe obesity (≥35) did not have increased total mortality (1·10 [0·87–1·41]) but they had the highest risk for cardiovascular mortality (1·88 [1·05–3·34]).

Interpretation

The better outcomes for cardiovascular and total mortality seen in the overweight and mildly obese groups could not be explained by adjustment for confounding factors. These findings could be explained by the lack of discriminatory power of BMI to differentiate between body fat and lean mass.

Introduction

The American Heart Association and American College of Cardiology guidelines for secondary prevention in coronary artery disease (CAD) list obesity as a major modifiable cardiovascular risk factor.1 About two-thirds of patients who have had myocardial infarction (MI) have a higher than normal body-mass index (BMI) of 25 or above.

There are several pathophysiological pathways by which obesity increases the risk for developing CAD and adverse cardiovascular events. Obesity reduces insulin sensitivity, enhances free fatty acid turnover, increases basal sympathetic tone, induces a hypercoagulable state, and promotes systemic inflammation, all of which contribute to the development and progression of CAD.2 In addition, obesity is a “conditional” risk for developing cardiovascular risk factors such as diabetes, dyslipidemia, hypertension, and obstructive sleep apnoea.3, 4 Although obesity is clearly a risk factor for developing CAD, once CAD has been established, the correlation of obesity with total mortality, cardiovascular mortality, infarction, and revascularisation is unclear. The relation between obesity and mortality in patients with CAD has so far only been investigated by post-hoc analysis of cohort studies, which have produced contradictory results.5, 6, 7, 8, 9

In view of the high prevalence of obesity in patients with CAD,10 we need a more accurate estimate of the link between obesity, and cardiovascular events and total mortality. Our aim was to undertake a systematic review of cohort studies and perform a meta-analysis to better estimate the effect of bodyweight and other measures of obesity on total mortality, cardiovascular mortality, reinfarction, and revascularisation in patients with established CAD.

Section snippets

Search strategy and selection criteria

We searched, with no language restrictions, the OVID/MEDLINE electronic database from 1966 to December, 2005, for studies reporting total mortality and cardiovascular events in patients with established CAD, on the basis of bodyweight or other measures of fat distribution. We used terms related to bodyweight (eg, body mass index, bodyweight, obesity, overweight, central obesity, body fat), mortality and other cardiovascular events (eg, cardiac death, cardiovascular death, survival, mortality,

Results

Of the 1560 articles and 34 abstracts identified, 54 studies met the inclusion criteria. On the whole, both reviewers were in agreement over which studies should be included (κ=0·79). Figure 1 shows details of study selection.

40 studies had weight groups based on BMI and the rest had BMI reported as a continuous variable or used another measure of obesity. The BMI group studies represented the core of this analysis and included 250 152 patients with CAD, with a mean follow-up of 3·8 years

Discussion

Our study shows that after grouping cohort studies with adjusted risks, a low BMI is strongly associated with an increased long-term risk of total mortality and other cardiovascular events. Overweight patients were consistently associated with a better survival and lower cardiovascular events. Obesity was associated with a higher total mortality only in patients with history of CABG. Severe obesity was associated with a significantly higher cardiovascular mortality but not with an increased

References (74)

  • DL McGee

    Body mass index and mortality: a meta-analysis based on person-level data from twenty-six observational studies

    Ann Epidemiol

    (2005)
  • S Yusuf et al.

    Obesity and the risk of myocardial infarction in 27,000 participants from 52 countries: a case-control study

    Lancet

    (2005)
  • HS Gurm et al.

    The impact of body mass index on short- and long-term outcomes inpatients undergoing coronary revascularization. Insights from the bypass angioplasty revascularization investigation (BARI)

    J Am Coll Cardiol

    (2002)
  • JM Johnston et al.

    The impact of body weight on outcome after percutaneous coronary intervention—the obesity paradox revisited: a report from the National, Heart, Lung, and Blood Institute Dynamic Registry

    J Am Coll Cardiol

    (2003)
  • HS Gurm et al.

    Impact of body mass index on outcome after percutaneous coronary intervention (the obesity paradox)

    Am J Cardiol

    (2002)
  • L Gruberg et al.

    Impact of body mass index on the outcome of patients with multivessel disease randomized to either coronary artery bypass grafting or stenting in the ARTS trial: The obesity paradox II?

    Am J Cardiol

    (2005)
  • L Gruberg et al.

    The impact of obesity on the short-term and long-term outcomes after percutaneous coronary intervention: the obesity paradox?

    J Am Coll Cardiol

    (2002)
  • J Kim et al.

    Obesity and the risk of early and late mortality after coronary artery bypass graft surgery

    Am Heart J

    (2003)
  • TA Schwann et al.

    Effects of body size on operative, intermediate, and long-term outcomes after coronary artery bypass operation

    Ann Thorac Surg

    (2001)
  • TD Rea et al.

    Body mass index and the risk of recurrent coronary events following acute myocardial infarction

    Am J Cardiol

    (2001)
  • F Lopez-Jimenez et al.

    Prevalence and secular trends of excess body weight and impact on outcomes after myocardial infarction in the community

    Chest

    (2004)
  • A Nigam et al.

    Excess weight at time of presentation of myocardial infarction is associated with lower initial mortality risks but higher long-term risks including recurrent re-infarction and cardiac death

    Int J Cardiol

    (2006)
  • HM Krumholz et al.

    Predicting one-year mortality among elderly survivors of hospitalization for an acute myocardial infarction: results from the Cooperative Cardiovascular Project

    J Am Coll Cardiol

    (2001)
  • LM Kennedy et al.

    The prognostic importance of body mass index after complicated myocardial infarction

    J Am Coll Cardiol

    (2005)
  • J Sierra-Johnson et al.

    Relation of body mass index to fatal and nonfatal cardiovascular events after cardiac rehabilitation

    Am J Cardiol

    (2005)
  • EL Eisenstein et al.

    Elevated body mass index and intermediate-term clinical outcomes after acute coronary syndromes

    Am J Med

    (2005)
  • VM Montori et al.

    Publication bias: a brief review for clinicians

    Mayo Clin Proc

    (2000)
  • FX Pi-Sunyer

    The obesity epidemic: pathophysiology and consequences of obesity

    Obes Res

    (2002)
  • RM Krauss et al.

    Obesity: impact on cardiovascular disease

    Circulation

    (1998)
  • AS Shamsuzzaman et al.

    Obstructive sleep apnea: implications for cardiac and vascular disease

    JAMA

    (2003)
  • F Lopez-Jimenez et al.

    Recognition, diagnosis and management of obesity after myocardial infarction

    Int J Obes (Lond)

    (2005)
  • KS Khan et al.
  • DF Stroup et al.

    Meta-analysis of observational studies in epidemiology: a proposal for reporting—Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group

    JAMA

    (2000)
  • Review Manager (RevMan)

    (2003)
  • LR Smith et al.

    Determinants of early versus late cardiac death in patients undergoing coronary artery bypass graft surgery

    Circulation

    (1991)
  • RR Arora et al.

    Restenosis after transluminal coronary angioplasty: a risk factor analysis

    Cathet Cardiovasc Diagn

    (1990)
  • JP Ottervanger et al.

    Long-term results after the glycoprotein IIb/IIIa inhibitor abciximab in unstable angina: one-year survival in the GUSTO IV-ACS (Global Use of Strategies To Open Occluded Coronary Arteries IV—Acute Coronary Syndrome) Trial

    Circulation

    (2003)
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