Anthropometric measurements and adverse outcomes in heart failure with reduced ejection fraction: revisiting the obesity paradox
Summary
Goals
Although body mass index (BMI) is the most widely used anthropometric measure, newer indices, such as waist-to-height ratio, better reflect the location and amount of ectopic fat, as well as skeletal weight, and may be more useful.
Methods and results
The prognostic value of several newer anthropometric indices was compared with that of BMI in patients with heart failure (HF) and reduced ejection fraction (HFrEF) enrolled in a prospective comparison of ARNI with ACEI to determine the impact on overall mortality and morbidity. in heart failure.
The primary outcome was hospitalization for HF or cardiovascular death. The association between anthropometric indices and outcomes was extensively adjusted for other prognostic variables, including natriuretic peptides.
An “obesity survival paradox” was identified related to a lower risk of mortality in those with a BMI ≥25 kg/m2 (compared with normal weight), but this was eliminated by adjustment for other prognostic variables. This paradox was less evident for the waist-to-height ratio (as an example of indices that do not incorporate weight) and was eliminated by adjusting: the adjusted hazard ratio (aHR) for all-cause mortality, for quintile 5 compared to quintile 1, it was 1.10 [95% confidence interval (CI) 0.87-1.39].
However, both BMI and waist-to-height ratio showed that higher adiposity was associated with a higher risk of the primary outcome and hospitalization for HF; this was most evident for the waist-to-height ratio and persisted after adjustment, e.g. The aHR for HF hospitalization for quintile 5 versus quintile 1 of waist-to-height ratio was 1.39 (95% CI: 1.06-1.81).
Conclusion
In patients with HFrEF, alternative anthropometric measurements showed no evidence of an “obesity survival paradox . ” Newer indices that do not incorporate weight showed that greater adiposity was clearly associated with a greater risk of hospitalization for HF.
Graphic summary : At the top of the figure the calculation of each of the anthropometric measurements is described. The bottom part of the figure shows risk outcomes based on continuous body mass index (left panel) and waist-to-height ratio (right panel). The solid line represents the hazard ratio and the shaded area the 95% confidence interval. The blue spline is adjusted for treatment and region. The red spline is adjusted for treatment, age, sex, region, systolic blood pressure, heart rate, estimated glomerular filtration rate, left ventricular ejection fraction, log of n-terminal B-type natriuretic peptide, body mass index (only in analyzes of waist-to-height ratio), New York Heart Association functional class, etiology of heart failure, duration of heart failure, previous hospitalization for heart failure, history of diabetes and atrial fibrillation. BMI, body mass index; BRI, body roundness index; BSA, body surface area; BSI, body shape index; CI: confidence interval; HF, heart failure; HR: hazard ratio; RFM, relative fat mass; WHR: waist-hip ratio; WHtR: waist-height ratio; WWI, weight-adjusted waist index.
Comments
New research has debunked the idea that there is an "obesity paradox ," in which heart failure patients who are overweight or obese are thought to be less likely to end up in hospital or die than people of normal weight. .
The study, published in the European Heart Journal , shows that if doctors measure their patients’ waist-to-height ratio, instead of looking at their body mass index (BMI), the supposed survival advantage for women people with a BMI of 25 kg/m2 or more disappears.
The "obesity paradox" relates to counterintuitive findings that suggest that although people are at greater risk of developing heart problems if they are overweight or obese, once a person has developed a heart condition, those with a higher BMI They seemed to be doing better and were less likely to die than those of normal weight. Several explanations have been suggested, including the fact that once someone has developed heart problems, a little extra fat somehow protects against further health problems and death, especially because people who develop serious, chronic disease at They often lose weight.
John McMurray, professor of medical cardiology at the University of Glasgow, UK, who led the latest research, said: "It has been suggested that living with obesity is good for patients with heart failure and reduced ejection fraction, which is when the main chamber of the heart cannot squeeze out normal amounts of blood. We knew this couldn’t be right and that obesity must be bad rather than good. We thought part of the problem was that BMI was a weak indicator of the amount of fatty tissue that a patient has.”
As Professor Stephan von Haehling, consultant cardiologist, and Dr Ryosuke Sato, research associate, both from Göttingen University Medical Center, Germany, write in an accompanying editorial, BMI does not take into account the fat composition of the body. body, muscle and bone, or where fat is distributed. “Would it be feasible to assume that an American professional wrestler (more muscle) and a Japanese sumo wrestler (more fat) with the same BMI would have a similar risk of cardiovascular disease? The same is true for people like Arnold Schwarzenegger in his youth when he played ’Terminator’ with a BMI of ~30 kg/m2."
The study is the first to look at different ways of measuring patients’ size and proportions, including BMI, but also anthropometric measures such as waist-to-height ratio, waist circumference and waist-to-hip ratio, and fit. of patients’ outcomes to take into account other factors that play a role in or predict these outcomes, such as levels of natriuretic peptides , hormones that are secreted into the blood when the heart is under pressure, as occurs with heart failure .
“Natriuretic peptides are the most important prognostic variable in patients with heart failure. Normally, levels of natriuretic peptides are increased in people with heart failure, but patients living with obesity have lower levels than those who are of normal weight,” Professor McMurray said.
Prof. McMurray and colleagues analyzed data from 1,832 women and 6,567 men with heart failure and reduced ejection fraction who were enrolled in the international PARADIGM-HF randomized controlled trial taking place in 47 countries on six continents. When patients were randomized, doctors collected data on BMI, blood pressure, anthropometric measurements, blood test results, medical history, and treatments. The researchers were interested in knowing which patients were hospitalized with heart failure or who died from it.
An "obesity survival paradox" showed lower mortality rates for people with a BMI of 25 kg/m2 or more [4], but this was eliminated when the researchers adjusted the results to take into account all the factors that may affect outcomes, including natriuretic peptide levels.
The study’s first author, Dr Jawad Butt, a researcher at Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark, who carried out the analyses, said: "The paradox was much less evident when we looked at waist-to-height ratios, and disappeared after adjustment for prognostic variables. After adjustment, both BMI and waist-to-height ratio showed that higher body fat was associated with a higher risk of death or hospitalization for heart failure, but this was more evident for waist-to-height ratio. Looking at the waist-to-height ratio, we found that the top 20% of people with the most fat had a 39% higher risk of being hospitalized for heart failure compared to people in the bottom 20% who had less fat".
Prof McMurray said: “Our study shows that there is no ’obesity survival paradox’ when we use better ways of measuring body fat. BMI does not take into account the location of fat on the body or its amount in relation to muscle or skeletal weight, which can differ by sex, age, and race. Specifically in heart failure, retained fluid also contributes to body weight. It is non-weight indices, such as waist-to-height ratio, that have clarified the true relationship between body fat and patient outcomes in our study, demonstrating that greater adiposity is actually associated with worse outcomes. , not better, outcomes, including high hospitalization rates and poorer health-related quality of life.
“Obesity is not good and is bad in patients with heart failure and reduced ejection fraction. These observations raise the question of whether weight loss could improve outcomes, and we need trials to test this. In the UK, the National Institute for Health and Care Excellence, NICE, now recommends that waist-to-height ratio be used instead of BMI for the general population, and we should also support this for heart failure patients.
“It is important because underdiagnosis of heart failure in people living with obesity is a major problem in primary care. Patients’ symptoms of shortness of breath are often dismissed as due solely to obesity. Obesity is a risk factor and driver of heart failure. While in the past weight loss may have been a concern for patients with heart failure and reduced ejection fraction, today it is obesity.”
Prof. von Haehling and Dr. Sato write in their editorial: “The current findings raise the alarm about the term ’obesity paradox’, which is claimed to be based on BMI. Can we tell obese patients with HF [heart failure] to stay as they are? To adequately address this question, not only should the obesity paradox be reviewed even in patients with heart failure with preserved ejection fraction (HFpEF) and in lean patients with heart failure by WHtR [waist-to-height ratio], which better reflects the pathophysiological processes of obesity, but further evidence is also warranted to validate the effect of weight loss in ’truly’ obese HF patients with a high WHtR.”
Limitations of the study are that it may be more difficult to accurately measure body shapes, such as waist circumference, especially when the measurements are made by different people; there may be more unknown factors that could affect the results; The analysis was carried out on measurements and other data taken at the time participants joined the study and did not take into account any changes in weight or waist circumference during the follow-up period; there was no data on the cardiorespiratory status of the participants, which could have an effect on the link between anthropometric measures and outcomes; and, finally, only 153 patients were underweight, with a BMI less than 18.5 kg/m2, and 171 patients with a waist-height index less than 0.4 (0.5 is considered a healthy index), therefore that the study findings cannot be extrapolated to patients with low BMI or waist-hip ratio.
