Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies
ABSTRACT 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.
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.
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 (> or =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]).
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.
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ABSTRACT: 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. A total of 2,499 consecutive patients requiring all types of cardiac surgery with cardiopulmonary bypass between January 2004 and February 2009 were prospectively 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. 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 Infarction (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). In our population, obesity increases Perioperative Myocardial Infarction 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.PLoS ONE 03/2015; 10(3):e0118858. DOI:10.1371/journal.pone.0118858 · 3.53 Impact Factor
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ABSTRACT: In clinical practice obesity is primarily diagnosed through the body mass index. In order to characterize patients affected by obesity the use of traditional anthropometric measures appears misleading. Beyond the body mass index, there are overwhelming evidences towards the relevance of a more detailed description of the individual phenotype by characterizing the main body components as free-fat mass, muscle mass, and fat mass. Among the numerous techniques actually available, bioelectrical impedance analysis seems to be the most suitable in a clinical setting because it is simple, inexpensive, noninvasive, and highly reproducible. To date, there is no consensus concerning the use of one preferred equation for the resting energy expenditure in overweight and/or obese population. Energy restriction alone is an effective strategy to achieve an early and significant weight loss, however it results in a reduction of both fat and lean mass therefore promoting or aggravating an unfavourable body composition (as sarcobesity) in terms of mortality and comorbidities. Therefore the implementation of daily levels of physical activity should be simultaneously promoted. The major role of muscle mass in the energy balance has been recently established by the rising prevalence of the combination of two condition as sarcopenia and obesity. Physical exercise stimulates energy expenditure, thereby directly improving energy balance, and also promotes adaptations such as fiber type, mitochondrial biogenesis, improvement of insulin resistance, and release of myokines, which may influence different tissues, including muscle.03/2015; 5(1):1-9. DOI:10.5662/wjm.v5.i1.1
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ABSTRACT: The impact of body mass index (BMI) on the clinical outcomes after percutaneous coronary intervention (PCI) in patients ≥75 years old remained unclear. A total of 1098 elderly patients undergoing PCI with stent implantation were recruited. Patients were divided into four groups by the value of BMI: Underweight (≤20.0 kg/m 2 ), normal weight (20.0-24.9 kg/m 2 ), overweight (25.0-29.9 kg/m 2 ) and obese (≥30.0 kg/m 2 ). Major clinical outcomes after PCI were compared between the groups. The primary endpoint was defined as in-hospital major adverse cardiovascular events (MACEs), which included death, myocardial infarction (MI) and target vessel revascularization. The secondary endpoint was defined as 1 year death. Logistic regression analysis was performed to adjust for the potential confounders. Totally, 1077 elderly patients with available BMIs were included in the analysis. Patients of underweight, normal weight, overweight and obese accounted for 5.6%, 45.4%, 41.5% and 7.5% of the population, respectively. Underweight patients were more likely to attract ST-segment elevation MI, and get accompanied with anemia or renal dysfunction. Meanwhile, they were less likely to achieve thrombolysis in MI 3 grade flow after PCI, and receive beta-blocker, angiotensin converting enzyme inhibitor or angiotensin receptor blocker after discharge. In underweight, normal weight, overweight and obese patients, in-hospital MACE were 1.7%, 2.7%, 3.8%, and 3.7% respectively (P = 0.68), and 1 year mortality rates were 5.0%, 3.9%, 5.1% and 3.7% (P = 0.80), without significant difference between the groups. Multivariate regression analysis showed that the value of BMI was not associated with in-hospital MACE in patients at 75 years old. The BMI "obese paradox" was not found in patients ≥75 years old. It was suggested that BMI may not be a sensitive predictor of adverse cardiovascular events in elderly patients.Chinese medical journal 01/2015; 128(5):638-43. DOI:10.4103/0366-6999.151662 · 1.02 Impact Factor