An autopsy study of coronary atherosclerosis and its relation to anthropometric measurements/indices of overweight and obesity in men

Nicotine dependence as an independent risk factor for atherosclerosis in the National Lung Screening Trial

Background

Atherosclerosis and COPD are systemic inflammatory diseases that share common risk factors including cigarette smoking. A high level of nicotine dependence is emerging as a recently identified risk factor for pulmonary impairment, chronic obstructive pulmonary disease and tobacco-related cancers. We hypothesized that nicotine dependence is associated with the risk of atherosclerosis in long-term cigarette smokers.

Methods

A nested case-control study was conducted within the National Lung Cancer Screening Trial- American College of Radiology Imaging Network. Cases were defined as having a new diagnosis of any type of atherosclerosis. Controls were matched on a 2:1 basis by age, sex, race, study center, smoking status, years of smoking, and frequency of smoking. Dependence was measured by the time to first cigarette after awakening (TTFC).

Results

The study included 166 cases and 286 controls. Compared to participants who smoked within 5 min after waking, the risk of atherosclerosis for participants who smoked an hour or more after waking was borderline non-significant (odds ratio = 0.49, 95% confidence intervals [CI] 0.23, 1.00). Findings were similar for men and women. For aortic atherosclerosis, the corresponding odds ratio was 0.24 (95% CI 0.08, 0.69). Hypertension was associated with an increased risk and body mass index was associated with a decreased risk of aortic atherosclerosis. The TTFC was unrelated to coronary atherosclerosis.

Conclusions

Compared to smoking immediately after waking, delaying an hour or more reduces the risk of aortic atherosclerosis even among long-term heavy smokers. Possible mechanisms that explain this association are intensity of smoking, inflammation and oxidative stress, and elevated lipid levels.

The role of obesity in carotid plaque instability: interaction with age, gender, and cardiovascular risk factors

BACKGROUND

In the last decade, several studies have reported an unexpected and seemingly paradoxical inverse correlation between BMI and incidence of cardiovascular diseases. This so called "obesity paradox effect" has been mainly investigated through imaging methods instead of histologic evaluation, which is still the best method to study the instability of carotid plaque. Therefore, the purpose of our study was to evaluate by histology the role of obesity in destabilization of carotid plaques and the interaction with age, gender and other major cerebrovascular risk factors.

METHODS

A total of 390 carotid plaques from symptomatic and asymptomatic patients submitted to endarterectomy, for whom complete clinical and laboratory assessment of major cardiovascular risk factors was available, were studied by histology. Patients with a BMI ≥ 30.0 kg/m2 were considered as obese. Data were analyzed by multivariate logistic regression and for each variable in the equation the estimated odds ratio (OR) was calculated.

RESULTS

Unstable carotid plaque OR for obese patients with age < 70 years was 5.91 (95% CI 1.17-29.80), thus being the highest OR compared to that of other risk factors. Unstable carotid plaque OR decreased to 4.61 (95% CI 0.54-39.19) in males ≥ 70 years, being only 0.93 (95% CI 0.25-3.52) among women. When obesity featured among metabolic syndrome risk factors, the OR for plaque destabilization was 3.97 (95% CI 1.81-6.22), a significantly higher value compared to OR in non-obese individuals with metabolic syndrome (OR = 1.48; 95% CI 0.86-2.31). Similar results were obtained when assessing the occurrence of acute cerebrovascular symptoms.

CONCLUSIONS

Results from our study appear to do not confirm any paradoxical effect of obesity on the carotid artery district. Conversely, obesity is confirmed to be an independent risk factor for carotid plaque destabilization, particularly in males aged < 70 years, significantly increasing such risk among patients with metabolic syndrome.

Association of Waist-Hip Ratio to Sudden Cardiac Death and Severe Coronary Atherosclerosis in Medicolegal Autopsies

Various modifiable and nonmodifiable risk factors, such as abdominal obesity, are known to affect the development of atherosclerotic cardiovascular disease and subsequent sudden cardiac death (SCD). The waist-hip ratio is a surrogate marker of visceral obesity that has been shown in various studies to be a better predictor of cardiovascular risk than the body mass index (BMI), a measurement of generalized obesity. Waist-hip ratio was measured prospectively on medicolegal autopsies performed for 1 year, in addition to standard measurements of BMI and heart weight, and histologic determination of severe coronary atherosclerosis (SCA, coronary artery diameter stenosis >75%). Logistic modeling was performed to determine any association between WHR, BMI, cardiovascular disease risk factors, heart weight, and SCD or SCA. Waist-hip ratio was not shown to be statistically significantly associated with either SCD (P = 0.68) or SCA (P = 0.14). Body mass index was shown to be significantly associated with SCA (P < 0.001), and heart weight was shown to be significantly associated with both SCD and SCA (P < 0.001, both). Waist-hip ratio, as a surrogate marker of central obesity and increased risk of atherosclerotic cardiovascular disease, is shown not to be statistically significantly associated with either SCD or SCA in postmortem cases.

Predictive value of body mass index to metabolic syndrome risk factors in Syrian adolescents

BACKGROUND

Obesity has become a serious epidemic health problem in both developing and developed countries. There is much evidence that obesity among adolescents contributed significantly to the development of type 2 diabetes and coronary heart disease in adulthood. Very limited information exists on the prevalence of overweight, obesity, and associated metabolic risk factors among Syrian adolescents. Therefore, the purpose of this study was to determine the relationship between obesity determined by body mass index and the major metabolic risk factors among Syrian adolescents.

METHODS

A cross-sectional study of a randomly selected sample of 2064 apparently healthy Syrian adolescents aged 18 to 19 years from Damascus city, in Syria, was performed. Body mass index and blood pressure were measured. Serum concentrations of glucose, triglycerides, total cholesterol, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol were determined. Metabolic syndrome was defined using the national criteria for each determined metabolic risk factor. Individuals with a body mass index 25 to 29.9 were classified as overweight, whereas individuals with a body mass index ≥30 were classified as obese. A receiver operating characteristics curve was drawn to determine appropriate cut-off points of the body mass index for defining overweight and obesity, and to indicate the performance of body mass index as a predictor of risk factors.

RESULTS

The obtained data showed that blood pressure and the overall mean concentrations of fasting blood sugar, triglycerides, cholesterol, low-density lipoprotein-cholesterol, and triglycerides/high-density lipoprotein-cholesterol were significantly higher in overweight and obese adolescent groups (p <0.0001) in comparison with the normal group. Based on receiver operating characteristics calculation for body mass index and some metabolic risks, the data suggest the best body mass index cut-offs ranged between 23.25 and 24.35 kg/m².

CONCLUSIONS

A strong association between overweight and obesity as determined by body mass index and high concentrations of metabolic syndrome components has been demonstrated. Although body mass index values were lower than the international cut-offs, these values were good predictors of some metabolic abnormalities in Syrian adolescents; body mass index is a good predictor of these abnormalities in this population.

An obesity paradox: an inverse correlation between body mass index and atherosclerosis of the aorta

BACKGROUND AND AIMS

Morbid obesity generally has been associated with higher morbidity and mortality for a variety of diseases. However, a number of exceptions to this have been reported and referred to as the "obesity paradox." The purpose of the present study was to obtain objective data on aortic atherosclerosis and its relationship to body mass index (BMI, kg/m²), based on autopsy findings in a large cohort of overweight and obese decedents.

METHODS

Decedents were ≥18 years who had autopsies between 2003 and 2014, a subset of whom were morbidly obese (BMI≥40). Autopsy findings were reviewed and compared to a control group (BMI<40) who had consecutive autopsies performed between January 2013 and June 2014. Atherosclerosis was assessed by gross pathologic examination using a semiquantitative grading scale (from 0 to 3), and for statistical analysis, the scores were stratified into two groups: nonsevere (<2) or severe (≥2).

RESULTS

There were 304 decedents in the study: 66 were morbidly obese (BMI≥40), 94 were either Class I or II obese (BMI 30-40), 127 were either overweight (BMI 25.0-29.9) or normal weight (BMI 20-24.9), and 17 were underweight (BMI<20). Decedents with mild atherosclerosis were significantly younger than those with severe disease (55.2 vs. 67.3, P<.0001). Decedents were further stratified by age and BMI. Univariate analysis revealed that decedents >60 years were more likely to have severe atherosclerosis than those ≤60 years (61% vs. 30%, P<.0001). There was a highly significant (P=.008) inverse relationship between severe aortic atherosclerosis and BMI. Twenty of 66 decedents (30%) with a BMI≥40 had severe atherosclerosis vs. 122 of 238 decedents (51%) with BMIs<40 (P=.001). As BMI increased, the probability of developing severe disease decreased. Hypertension increased the probability of having severe atherosclerosis (54% vs. 33%, P=.007). After adjusting for other covariates, multivariable analysis revealed that age and hypertension were still positively correlated with the severity of atherosclerosis (P=.014 and 0.028, respectively), and the inverse relationship between BMI and atherosclerosis remained (adjusted relative risk of BMI≥40 vs. <40=0.64, 95% confidence interval: 0.4-1; P=.03).

CONCLUSIONS

Our data extend the previously described obesity paradox to another disease entity, atherosclerosis of the aorta. Morbid obesity appeared to have a protective effect for developing severe aortic atherosclerosis, for the reasons for which are yet to be determined. However, the mean age at death of decedents with BMIs≥40 was younger than those with BMIs in the 20-30 range (55.9 vs. 63.2 years, P=.001), confirming that morbid obesity was not associated with increased longevity.

Association between adiposity and systemic atherosclerosis: a protocol of a cross-sectional autopsy study

INTRODUCTION

Adiposity has been associated with atherosclerosis in clinical studies. However, few autopsy studies have investigated this association, and they had only examined the coronary artery disease. Moreover, most studies had small sample sizes and were limited to middle-aged or young adults. Our aim is to investigate the association between adiposity and systemic atherosclerosis in an autopsy study.

METHODS AND ANALYSIS

A sample of 240 deceased with 30 years or more will be evaluated. The sample size was calculated using the lowest correlation coefficient found in previous studies (r=0.109), assuming a power of 90% and α=0.05. We will collect information about sociodemographics, frequency of previous contact of the deceased's next of kin and cardiovascular risk factors. We will measure neck, waist and hip circumferences, weight, height and abdominal subcutaneous tissue thickness, and then we will calculate the body mass index, waist-to-hip ratio, waist-to-height ratio and body shape index. We will also weigh the pericardial and abdominal visceral fat, the heart, and we will measure the left ventricular wall thickness. We will evaluate the presence of myocardial infarction, the degree of atherosclerosis in the aorta, carotid, coronary and cerebral arteries and plaque composition in carotid, coronary and cerebral arteries. For each individual, we will fix arterial and adipose tissue samples in 10% formalin and freeze another adipose tissue sample at -80°C for future studies.

ETHICS AND DISSEMINATION

Ethical approval was granted by the Ethics Committee of University of Sao Paulo Medical School, Brazil. Results will be submitted for publication in a peer-reviewed journal.

VALIDITY OF USING WAIST AND HIP CIRCUMFERENCE MEASUREMENTS TO DETERMINE BODY COMPOSITION OF YOUNG SYRIAN MEN

This study examined the relation between waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHpR), waist-to-height ratio (WHtR) and triceps skin-fold thickness and percentage body fat in young Syrian men. The aim was to develop equations that can use these anthropometric characteristics to estimate percentage body fat in this group of subjects. A total of 2470 healthy Syrian men aged 18-19 years were enrolled in the study in 2010-2011. The anthropometric characteristics of all subjects were measured. The percentage body fat of 213 of the subjects was determined using the deuterium dilution (DD) technique as a reference method. The validity of using WC, HC, WHpR and WHtR to calculate percentage body fat, in comparison with the reference method (DD technique), was assessed by calculating biases and limits of agreement. The estimates of percentage body fat using 'WC' and 'WC with triceps skin-fold' measurements ranged from 13.00±5.56% to 14.55±8.63%, and were lower than those determined using the reference method (21.32±6.42%). A better prediction equation is proposed for young adults, based on a multiple linear regression model using WC, HC and WHtR.

A correlation between the weight of visceral adipose tissue and selected anthropometric indices: an autopsy study

WHAT IS ALREADY KNOWN ON THE SUBJECT

Several anthropometric indices are used as an estimation of the true amount of body fat, e.g. the body mass index (BMI). These indices correlate well with each other and with non-invasive measurements of total body fat and visceral adipose tissue. The indices generally show a strong correlation with cardiovascular disease and diabetes mellitus.

WHAT THIS STUDY ADDS

Direct measurement of visceral adipose tissue by weight (VAW) from autopsy cases positively correlates with the anthropometric indices. VAW also positively correlates with fatty tissue thickness at separate locations, i.e. renal capsular and epicardial fatty tissue. VAW is positively correlated with the severity of cardiosclerosis and diabetes mellitus, but there is no significant difference in VAW between deaths from cardiovascular complications and other natural deaths.

SUMMARY

Different anthropometric indices and non-invasive methods have been used to estimate the total burden of body fat. Increased visceral adipose tissue is believed to involve elevated risk for cardiovascular disease, type 2 diabetes, chronic kidney disease and hypertension. At present, the optimal method to estimate the visceral and total amount of fat remains undecided. In the present study of 201 autopsy cases, direct measurement of visceral adipose tissue by weight (VAW) has been compared to common anthropometric indices, namely body mass index (BMI), waist-to-hip ratio (W/Hip ratio), waist-to-height ratio (W/Height ratio), body adiposity index (BAI), waist circumference and abdominal wall thickness. The prevalence and severity of cardiovascular disease, diabetes mellitus and cause of death were also correlated with the anthropometric data. The outcome was that all anthropometric measurements showed a significant positive correlation with the weight of visceral adipose tissue, and the r-value of the comparison to waist circumference was the highest (r = 0.82). Thickness of fatty tissue enveloping the kidneys and heart, as well as heart weight, was also strongly correlated with VAW. VAW was significantly higher in men compared with women, and in diabetes mellitus compared with non-diabetic patients. VAW was also positively correlated with the severity of coronary artery sclerosis. On the contrary, there was no significant difference between high and low VAW comparing between deaths from cardiovascular complications and natural deaths from other causes. The conclusion is that the anthropometric measurements give a good approximation of the real amount of visceral fat, and that waist circumference and W/Height ratio show the best correlations.