From the BMI paradox to the obesity paradox: the obesity-mortality association in coronary heart disease

Effects of Initial Body Mass Index and Weight Change on All-Cause Mortality: A 10-Year Cohort Study in Korea

We evaluated the effects of baseline body mass index (BMI) and its changes over 4 years on all-cause mortality in Korean population. We analyzed 351 735 participants whose BMI was measured in both 2002/2003 and 2006/2007. Mortality was assessed until 2013. Multivariate hazard ratios for all-cause mortality were estimated. Underweight and severe obesity with BMI >30 kg/m2 were significantly associated with higher mortality. Similarly, >5% decrease or >10% increase of BMI for 4 years was associated with the increased risk of death. Comparing the results between baseline BMI and BMI change, the BMI change showed more stable associations with mortality than the baseline BMI in subgroup analysis such as nonsmokers and healthy participants. This study suggests that BMI change could be a useful health indicator along with obesity level by BMI. In addition, maintaining a healthy weight is needed for longevity, but rapid weight change should be carefully monitored.

DR, Lee DH. Persistent Organic Pollutants and Type 2 Diabetes: A Critical Review of Review Articles

Low dose persistent organic pollutants (POPs) have emerged as a new risk for type 2 diabetes (T2D). Despite substantial evidence from human and experimental studies, there are several critical issues which have not been properly addressed by POPs researchers. First, as POPs exist as mixtures, findings about POPs from human studies should be interpreted from the viewpoint of lipophilic chemical mixtures which include both measured and unmeasured POPs. Second, as POPs can directly reduce insulin secretion of beta cells, the role of POPs may be more prominent in the development of beta-cell dysfunction-dominant T2D rather than insulin resistance-dominant T2D. Third, there are multidimensional interrelationships between POPs and adipose tissue. Even though POPs are now considered as a new risk factor for T2D, independent of obesity, POPs and obesity are mechanistically linked to each other. POPs are involved in key mechanisms linking obesity and T2D, such as chronic inflammation of adipose tissue and lipotoxicity with ectopic fat accumulation. Also, POPs can explain puzzling human findings which suggest benefits of obesity because healthy adipose tissue can be protective by reducing the amount of POPs reaching other organs. Fourth, non-linear dose-response relationships between POPs and T2D are biologically possible. Although POPs are well-known endocrine disrupting chemicals (EDCs), mitochondrial dysfunction may be a more plausible mechanism due to unpredictability of EDC mixtures. As adipose tissue plays a role as an internal exposure source of POPs, how to manage POPs inside us may be essential to protect against harms of POPs.

Body mass index as a biomarker for the evaluation of the "Obesity Paradox" among inpatients

BACKGROUND

Overweight and obesity are, on the one hand, recognized as risk factors for many health-related disorders, and, on the other, as favorable prognostic factors in various patients treated for several different conditions; what is called the "obesity paradox". Until now, the existence of this phenomenon among a general population of consecutive inpatients has not been evaluated. We decided, therefore, to perform an evaluation.

PATIENTS AND METHODS

Historical prospective analysis of the medical documentation of 23 603 hospitalizations during two consecutive years in one center was performed. The outcomes measured were as follows: length of stay, in-hospital all-cause mortality, and non-scheduled readmission in the 14-day, 30-day and one-year periods following discharge.

RESULTS

Overweight and obese patients had a lower or similar prevalence of the measured outcomes than malnourished patients and those of normal weight. Adjustment of the standard WHO BMI ranges for patients aged ≥65 y (normal weight BMI range 23-33 kg/m²) made these differences more apparent. In logistic regression, the ratio of fat to fat-free body mass was a stronger and unfavorable risk factor compared with BMI for the measured outcomes.

CONCLUSIONS

The greatest risk of all-cause in-hospital death and readmission concerned malnourished inpatients. Compared to patients with a normal BMI range, overweight and obesity had a lower or similar (but not greater) risk of the outcomes measured. However, due to several BMI limitations, our observations should be interpreted as suggesting a "BMI paradox", rather than an "obesity paradox".

Associations of changes in body mass index with all-cause and cardiovascular mortality in healthy middle-aged adults

Background

Conflicting data exist regarding the association of body mass index (BMI) changes with all-cause and cardiovascular (CV) mortality. The current study investigated the association between changes in BMI and all-cause, CV, and non-CV mortality in a large cohort of middle-aged adults.

Methods

A total of 379,535 adults over 40 years of age without pre-existing CV disease or cancer at baseline were enrolled to undergo a series of at least three health examinations of biennial intervals. Changes in BMI between baseline, midpoint follow-up, and final health examination during mean 9.3 years were defined according to the pattern of BMI change as follows: stable, sustained gain, sustained loss, and fluctuation. The relationship between BMI change category and mortality was assessed by multivariate Cox regression reporting hazard ratio (HR) with 95% confidence interval (95% CI).

Results

During a mean follow-up of 10.7 years for mortality, 12,378 deaths occurred from all causes, of which 2,114 were CV and 10,264 were non-CV deaths. Sustained BMI gain was associated with the lower risk of all-cause (HR 0.89, 95% CI: 0.83–0.95), CV (HR 0.84, 95% CI 0.72–0.98), and non-CV mortality (HR 0.90, 95% CI 0.84–0.96) compared with stable BMI. Conversely, sustained BMI loss (HR 1.25, 95% CI 1.19–1.32) and fluctuation (HR 1.13, 95% CI 1.08–1.19) displayed a higher risk of all-cause mortality compared with stable BMI, which was mainly attributable to the increase in non-CV mortality.

Conclusion

Sustained BMI gains were associated with reduced risk of all-cause, CV, and non-CV mortality in middle-aged healthy adults.

Exploring the Crosstalk between Adipose Tissue and the Cardiovascular System

Obesity is a clinical entity critically involved in the development and progression of cardiovascular disease (CVD), which is characterised by variable expansion of adipose tissue (AT) mass across the body as well as by phenotypic alterations in AT. AT is able to secrete a diverse spectrum of biologically active substances called adipocytokines, which reach the cardiovascular system via both endocrine and paracrine routes, potentially regulating a variety of physiological and pathophysiological responses in the vasculature and heart. Such responses include regulation of inflammation and oxidative stress as well as cell proliferation, migration and hypertrophy. Furthermore, clinical observations such as the “obesity paradox,” namely the fact that moderately obese patients with CVD have favourable clinical outcome, strongly indicate that the biological “quality” of AT may be far more crucial than its overall mass in the regulation of CVD pathogenesis. In this work, we describe the anatomical and biological diversity of AT in health and metabolic disease; we next explore its association with CVD and, importantly, novel evidence for its dynamic crosstalk with the cardiovascular system, which could regulate CVD pathogenesis.

Associations between body mass index and mortality or cardiovascular events in a general Korean population

Background/Objectives

The relationship between body mass index (BMI) and mortality remains controversial. Furthermore, the association between BMI and cardiovascular events (CVE) is not conclusive and may differ by ethnicity. We aimed to estimate the associations between the BMI and mortality or cardiovascular disease in a general Korean population.

Subjects/Methods

This study was based on a sample cohort database released by the Korean National Health Insurance Service. We analyzed a total of 415,796 adults older than 30 years of age who had undergone a national health examination at least once from 2002 to 2012. Hazard ratios for death and cardiovascular events were calculated using Cox proportional hazards models.

Results

For both men and women, BMI and overall mortality showed a U-shaped association, with the lowest mortality rate among those with a BMI of 25–27.4 kg/m². Compared with them, subjects with a BMI ≥ 30kg/m², men with a BMI < 25 kg/m², and women with a BMI < 22.5 kg/m² showed significantly higher overall mortality. Additionally, men with a BMI < 22.5 kg/m² and women with a BMI < 20 kg/m² displayed an increased risk of cardiovascular mortality. Unlike the mortality trend, the CVD events trend showed a linearly positive association. The risk of a CVE was the lowest in men with a BMI ranging from 20 to 22.4 kg/m² and in women with a BMI < 20 kg/m².

Conclusions

The BMI showed a U-shaped association with overall mortality, where slightly obese subjects showed the lowest rate of mortality. The CVE exhibited a linear association with the BMI, where the lowest risk was observed for normal weight subjects in a general Korean population.

Dipeptidyl peptidase IV inhibitors as novel regulators of vascular disease

Dipeptidyl peptidase IV (DPP-IV) has been revealed as an adipokine with potential relevance in cardiovascular disease (CVD), while clinically used DPP-IV inhibitors have demonstrated beneficial cardiovascular effects in several experimental studies. Perivascular adipose tissue (PVAT) is a unique adipose tissue depot in close anatomical proximity and bidirectional functional interaction with the vascular wall, which is a source of DPP-IV and its biology may be influenced by DPP-IV inhibition. Recently, DPP-IV inhibition has been associated with decreased local inflammation and oxidative stress both in the vascular wall and the PVAT, potentially regulating atherogenesis progression in vivo. DPP-IV inhibition may thus be a promising target in cardiovascular disease. However, the exact pleiotropic mechanisms that underlie the cardiovascular effects of DPP-IV inhibition need to be clarified, while the in vivo benefit of DPP-IV inhibition in humans remains unclear.

The role of epicardial adipose tissue in cardiac biology: classic concepts and emerging roles

Classic concepts about the role of epicardial adipose tissue (EpAT) in heart physiology include its role in cardiac metabolism, mechanical protection of coronaries, innervation and possibly cryoprotection of the heart too. Nevertheless, recent evidence has revealed that epicardial adipose tissue regulates multiple aspects of cardiac biology including myocardial redox state, intracellular Ca²⁺ cycling, the electrophysiological and contractile properties of cardiomyocytes, cardiac fibrosis as well as coronary atherosclerosis progression. Moreover, it is now understood that the communication between EpAT and the heart is regulated by complex bidirectional pathways, since not only do adipokines regulate cardiac function, but also the heart affects EpAT biology via paracrine 'reverse' signalling. Such complex interactions as well as epicardial fat accumulation as a consequence of cardiac disease and epicardium to adipocyte differentiation should be taken into account by the clinical studies investigating EpAT as a risk marker and its potential as a therapeutic target against cardiovascular disease. Further in-depth exploration of the molecular mechanisms regulating the cross-talk between the heart and EpAT is expected to enhance our understanding regarding the role of the latter in cardiac physiology and relevant disease mechanisms.

Persistent organic pollutants in adipose tissue should be considered in obesity research

Although low doses of persistent organic pollutants (POPs), strong lipophilic chemicals with long half-lives, have been linked to various endocrine, immune, nervous and reproductive system diseases, few obesity studies have considered adipose tissue as an important POPs exposure source. Because the toxicodynamics of POPs relate directly to the dynamics of adiposity, POPs might explain puzzling findings in obesity research. In two people exposed to the same amounts of environmental POPs, the one having more adipose tissue may be advantaged because POPs storage in adipose tissue can reduce burden on other critical organs. Therefore, adipose tissue can play a protective role against the POPs effects. However, two situations increase the POPs release from adipose tissue into the circulation, thereby increasing the risk that they will reach critical organs: (i) weight loss and (ii) insulin resistance. In contrast, weight gain reduces this possibility. Therefore, avoiding harmful health effects of POPs may mostly contradict conventional judgments about obesity and weight change. These contradictory situations can explain the obesity paradox, the adverse effects of intensive intentional weight loss and the protective effects of obesity against dementia. Future studies should consider that adipose tissue is widely contaminated with POPs in modern society.

Prognostic implications of epicardial fat volume quantification in acute pericarditis

BACKGROUND

The pathophysiology of acute pericarditis remains largely unknown, and biomarkers are needed to identify patients susceptible to complications. As adipose tissue has a pivotal role in cardiovascular disease pathogenesis, we hypothesized that quantification of epicardial fat volume (EFV) provides prognostic information in patients with acute pericarditis.

MATERIALS AND METHODS

Fifty (n = 50) patients with first diagnosis of acute pericarditis were enrolled in this study. Patients underwent a cardiac computerized tomography (CT) scan to quantify EFV on a dedicated workstation. Patients were followed up in hospital for atrial fibrillation (AF) development and up to 18 months for the composite clinical endpoint of development of constrictive, recurrent or incessant pericarditis or poor response to nonsteroidal anti-inflammatory drugs.

RESULTS

Patients presenting with chest pain had lower EFV vs. patients without chest pain (167·2 ± 21·7 vs. 105·1 ± 11·1 cm³ , respectively, P < 0·01); EFV (but not body mass index) was strongly positively correlated with pericardial effusion size (r = 0·395, P = 0·007) and associated with in-hospital AF. At follow-up, patients that reached the composite clinical endpoint had lower EFV (P < 0·05). After adjustment for age, EFV was associated with lower odds ratio for the composite clinical endpoint point of poor response to NSAIDs or the development of constrictive, recurrent or incessant pericarditis during follow-up (per 20 cm³ increase in EFV: OR = 0·802 [0·656-0·981], P < 0·05).

CONCLUSIONS

We report for the first time a significant association of EFV with the clinical features and the outcome of patients with acute pericarditis. Measurement of EFV by CT may have important prognostic implications in these patients.

Body Adiposity Index Performance in Estimating Body Fat Percentage in Colombian College Students: Findings from the FUPRECOL-Adults Study

Recently, a body adiposity index (BAI = (hip circumference)/((height)(1.5))-18) was developed and validated in adult populations. The aim of this study was to evaluate the performance of BAI in estimating percentage body fat (BF%) in a sample of Colombian collegiate young adults. The participants were comprised of 903 volunteers (52% females, mean age = 21.4 years ± 3.3). We used the Lin's concordance correlation coefficient, linear regression, Bland-Altman's agreement analysis, concordance correlation coefficient (ρc) and the coefficient of determination (R²) between BAI, and BF%; by bioelectrical impedance analysis (BIA)). The correlation between the two methods of estimating BF% was R² = 0.384, p < 0.001. A paired-sample t-test showed a difference between the methods (BIA BF% = 16.2 ± 3.1, BAI BF% = 30.0 ± 5.4%; p < 0.001). For BIA, bias value was 6.0 ± 6.2 BF% (95% confidence interval (CI) = -6.0 to 18.2), indicating that the BAI method overestimated BF% relative to the reference method. Lin's concordance correlation coefficient was poor (ρc = 0.014, 95% CI = -0.124 to 0.135; p = 0.414). In Colombian college students, there was poor agreement between BAI- and BIA-based estimates of BF%, and so BAI is not accurate in people with low or high body fat percentage levels.

Perivascular adipose tissue as a regulator of vascular disease pathogenesis: identifying novel therapeutic targets

Adipose tissue (AT) is an active endocrine organ with the ability to dynamically secrete a wide range of adipocytokines. Importantly, its secretory profile is altered in various cardiovascular disease states. AT surrounding vessels, or perivascular AT (PVAT), is recognized in particular as an important local regulator of vascular function and dysfunction. Specifically, PVAT has the ability to sense vascular paracrine signals and respond by secreting a variety of vasoactive adipocytokines. Due to the crucial role of PVAT in regulating many aspects of vascular biology, it may constitute a novel therapeutic target for the prevention and treatment of vascular disease pathogenesis. Signalling pathways in PVAT, such as those using adiponectin, H₂ S, glucagon-like peptide 1 or pro-inflammatory cytokines, are among the potential novel pharmacological therapeutic targets of PVAT.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Predictive Validity of the Body Adiposity Index in Overweight and Obese Adults Using Dual-Energy X-ray Absorptiometry

The body adiposity index (BAI) is a recent anthropometric measure proven to be valid in predicting body fat percentage (BF%) in some populations. However, the results have been inconsistent across populations. This study was designed to verify the validity of BAI in predicting BF% in a sample of overweight/obese adults, using dual-energy X-ray absorptiometry (DEXA) as the reference method. A cross-sectional study was conducted in 48 participants (54% women, mean age 41.0 ± 7.3 years old). DEXA was used as the “gold standard” to determine BF%. Pearson’s correlation coefficient was used to evaluate the association between BAI and BF%, as assessed by DEXA. A paired sample t-test was used to test differences in mean BF% obtained with BAI and DEXA methods. To evaluate the concordance between BF% as measured by DEXA and as estimated by BAI, we used Lin’s concordance correlation coefficient and Bland–Altman agreement analysis. The correlation between BF% obtained by DEXA and that estimated by BAI was r = 0.844, p < 0.001. Paired t-test showed a significant mean difference in BF% between methods (BAI = 33.3 ± 6.2 vs. DEXA 39.0 ± 6.1; p < 0.001). The bias of the BAI was −6.0 ± 3.0 BF% (95% CI = −12.0 to 1.0), indicating that the BAI method significantly underestimated the BF% compared to the reference method. Lin’s concordance correlation coefficient was considered stronger (ρc = 0.923, 95% CI = 0.862 to 0.957). In obese adults, BAI presented low agreement with BF% measured by DEXA; therefore, BAI is not recommended for BF% prediction in this overweight/obese sample studied.