Review
Obesity paradox in elderly patients with cardiovascular diseases

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Abstract

Many elderly people are affected by cardiovascular diseases (CVD) and the majority of CVD patients are elderly people. For both patient populations, studies have shown that a high body mass index (BMI) is associated with lower mortality when compared to normal weight subjects, a fact commonly known as the “obesity paradox”. Whether the correlation between obesity and better survival is based on methodological influences and other non-causal factors alone, or whether there is a causal link between obesity and a better survival in these subjects remains widely unexplored. The interrelation between aging, obesity, CVD, frailty and inflammation is a current issue of intensive research. For the elderly, parameters which include measures of body composition, fat and fat-free mass are of greater importance than BMI. Weight management in elderly people with cardiovascular diseases should aim at improvement and maintenance of physical function and quality of life rather than prevention of medical problems associated with obesity in younger and middle aged patients. Although many studies have shown that weight loss in elderly patients is associated with a poor prognosis, recent data demonstrate that intentional weight reduction in obese elderly people ameliorates the cardiovascular risk profile, reduces chronic inflammation and is correlated with an improved quality of life. An individual approach to weight management that includes the participation of the patient, co-morbidity, functional status, and social support should be aspired.

Introduction

Recent publications have shown that obesity in different populations such as elderly people and patients with cardiovascular diseases (CVD), like heart failure (HF) or coronary artery disease (CAD), is surprisingly not associated with a higher but with a lower mortality risk. This fact has thus been termed “obesity paradox”. A major overlap between those two population groups, in which the obesity paradox is usually observed, should here be taken into account: many elderly people are affected by CVD and the majority of CVD patients are elderly people [1], [2].

In the general population overweight and obesity are well-known risk factors for the development of cardiovascular diseases [3], [4] like HF [5], ischemic heart diseases [6], abnormal left ventricular geometry, endothelial dysfunction, systolic and diastolic dysfunction and atrial fibrillation [4]. Overweight and obesity increase overall mortality and predict premature death [7], [8], [9], [10]. Furthermore obesity is associated with the development of cardiovascular risk factors like increased insulin resistance and type 2 diabetes mellitus, hypertension and dyslipidemia. The majority of studies evaluating obesity-related cardiovascular risk factors have been conducted in middle-aged, not in older adults, however, the prevalences of most of the obesity-related cardiovascular risk factors, such as hypertension and diabetes mellitus increase with age.

Prevalence of overweight and obesity are increasing in all age groups, including elderly people [11], [12], [13]. On the other hand, until recently, underweight, malnutrition and frailty in elderly people constituted the most important issues. However, the increase in prevalence of overweight and obesity due to an increase in this overall prevalence and due to the ongoing expansion of the elderly proportion in the population in industrial nations has led to a focus of this problem in the elderly, too. Obesity in older subjects is associated with increased morbidity such as infections [14], functional limitations and poor quality of life [15], [16], and obese older persons are admitted more frequently to nursing homes compared to those who are not [17]. Additionally, obesity in the elderly is correlated with decreased autonomy and mobility, with increased handicap in activities of daily living (such as personal hygiene, washing and eating) and instrumental activities of daily living (such as climbing stairs and shopping) [18]. A high BMI is associated with a lower quality of life, as a study in 5362 patients with coronary artery diseases one year after their index cardiac catheterization revealed. This is especially marked in subjects with severe obesity [19].

If the role of overweight and obesity in older patients and in patients with heart diseases is controversial, clinical consequences and the role of weight management in elderly patients, in patients with heart disease and in subjects with a combination of both are even more so. Hence, it was the aim of this review to analyze the role of obesity in the elderly in the development of cardiovascular risk factors and CVD. Furthermore, the so called obesity paradox in elderly and in patients with CVD is analyzed and possible explanations discussed. The association of aging, obesity, CVD and mortality and underlying patho-physiological mechanisms are reviewed and the effect of weight loss in elderly subjects and in patients with CVD examined. The recommendations of medical associations in terms of weight management in patients for whom an obesity paradox has been reported are accumulated, and based on the analyzed literature, possible clinical implications are summarized.

Section snippets

Definition of obesity

Obesity is commonly classified as BMI  30 kg/m, whereas a BMI < 18.5 is classified as underweight, a BMI of 18.5–24.9 as normal weight and a BMI of 25–29.9 as overweight [20], [21]. This classification does not take into account sex or age. In a systematic meta-analysis BMI cut-offs to diagnose obesity showed a pooled sensitivity of only 0.50 (95% CI 0.43–0.57) and a specificity of 0.90 (95% CI 0.86–0.94) [22]. In older persons, age-related changes in body composition like decrease in fat free

The obesity paradox

An unexpected finding which showed that obese patients with terminal renal insufficiency and hemodialyses seemed to live longer compared to normal weight subjects formed the basis for the “obesity-survival paradox”, first published in 1999 [28]. The fact that obesity and other classical cardiovascular risk factors like hypercholesterolemia and hypertension apparently seemed to decrease and not increase the risk in chronic diseases, like terminal kidney diseases and chronic HF, was acknowledged

Prevalence of cardiovascular risk factors in the elderly

The metabolic syndrome and its components which include excess abdominal fat, insulin-resistance, dyslipidemia, and high blood pressure are highly prevalent in older populations (NCEP, 2002). The prevalence of the metabolic syndrome increases with age and reaches a peak in men aged 50–70 years and women aged 60–80 years [39]. In the adult population with age fasting plasma glucose and postprandial glucose increase by 1–2 mg/dl and 10–20 mg/dl, respectively, for each decade [40]. As a consequence,

Obesity in the elderly, cardiovascular risk factors and risk of cardiovascular diseases

Abdominal obesity is associated with the development of the metabolic syndrome, even in men and women aged 70–79 years [44]. Older adults who are physically active and do not have increased abdominal circumference are much less likely to develop type 2 diabetes mellitus [45]. Obesity and hypertension continue to be correlated, even in old age [46], [47]. Dyslipidemia, low HDL-cholesterol and high triglycerides are also associated with abdominal obesity, even in old adults [48], [49], [50]. In a

Obesity and mortality in older people

In the general population, all-cause mortality as well as mortality due to cardiovascular diseases depending on the BMI show a J-shaped curve. Both a low and a very high BMI are associated with increased overall as well as cause-specific mortality [3], [57], [58]. In the general population the nadir of this J-shaped curve was found at a BMI of 23.5 to 24.9 in men and 22.0 to 23.4 in women [57]. For older people, a U- or J-shaped mortality curve depending on the BMI has also been described, with

Obesity and mortality in patients with heart failure

In a meta-analysis examining the mortality in HF patients by BMI, nine observational studies were analyzed, including a total sample of 28,209 subjects [63]. The mean age in these studies ranged from 51 to 72 years, the proportion of females ranged from 13 to 39%. In all of these studies overweight and obesity were associated with a lower all-cause mortality risk compared to normal weight, although this association was not statistically significant in either of the studies. The pooled odds ratio

Obesity and mortality in patients with ischemic heart disease

In a meta-analysis, including 22 cohort studies with a total sample size of 196,084 subjects after coronary revascularization the mortality was analyzed by BMI categories [72]. Out of these there were ten studies on mortality post-percutaneous coronary intervention (PCI). The subjects had a mean age between 60 and 67 years and the proportion of females was between 18 and 33%. In the meta-analysis, in the subgroup of post-PCI subjects the odds ratios for 30-day in-hospital mortality for

Possible explanations for the obesity paradox

The so called obesity paradox in elderly subjects and in patients with cardiovascular diseases has been critically analyzed by a number of review articles [83], [84], [85], [86]. The studies that show a significant statistic association between a high BMI and reduced overall mortality are all observational studies and not randomized clinical trials. Based on this design, no clear conclusions can be drawn with regards to causality. A number of potential methodological influences and other

Association between aging, obesity, cardiovascular diseases and mortality and possible involved patho-physiological mechanisms

The association between aging, obesity, cardiovascular diseases and mortality and the role of frailty and inflammation in this cascade are depicted in Fig. 1. In this figure also potential explanations which are discussed to be involved in the obesity paradox are outlined. Aging is not only an independent risk factor for cardiovascular diseases and mortality, aging is also associated with fat redistribution. With age, body composition changes with an increase in fat mass and a decrease in

Effects of weight loss in the elderly

There are several observational studies in which the effect of weight loss on mortality in older age groups has been evaluated. Most studies show that recent weight loss is associated with increased mortality [120], [121], [122]. In a review of 17 studies of weight loss and all-cause mortality the conclusion was that those who remained weight-stable had the lowest mortality rate [123].

In a prospective study of 5722 Swedish overweight and obese, but otherwise healthy men who lost weight were

Recommendation for weight loss in the elderly with CVD

The American Heart Association recommends weight reduction in patients with HF and with a BMI of > 40 kg/m². Weight loss should not be encouraged in patients with HF if the BMI is < 30 kg/m2, but patients should rather be encouraged to monitor for loss of appetite, unexpected weight loss, and muscle wasting [144]. There is no specific recommendation for elderly people with HF, but in the recommendation it is stated that the vast majority of persons with HF seen in clinics and hospitals are older

Conclusion

The clinical implications of the observed interrelation between a high BMI and a lower mortality in the elderly and in patients with cardiovascular diseases remain inconclusive. Since there is a big overlap between elderly patients and patients with CVD, it remains unclear which medical condition causes the so called obesity paradox. Intentional weight reduction as a result of personal choice even in elderly patients with obesity, especially with severe obesity, seems to be beneficial with

Acknowledgement

The authors would like to thank Katharina Viktoria Stein for proof-reading the manuscript. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [147].

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