Measuring body fat-How accurate is the extrapolation of predictive models in epidemiology?

Excess fat is a risk factor for many chronic diseases which can lead to premature mortality. Many studies have proposed predictive equations for body fat mass and body fat mass percentage based on anthropometric measures in relation to age and sex. However, the use of these predictive equations on other subject samples may not be relevant. Our objective is to assess whether the predictive equations proposed in the literature are generalizable to any population. We obtained fat mass and fat percentage on a reference population using Absorptiometry DXA. The predictive equations were applied to our population and the mean and individual differences between actual and estimated values were obtained. Predictive equations obtained from a reduced number of subjects have a very high Standard Error of Estimate (>3) and therefore their accuracy is not acceptable. Only the formulae established from a large number of individuals allow the estimation of values whose Standard Error of Estimate is less than 3. These equations, thanks to the large sample size, include a sufficiently large variability in anthropometric measurements covering the diversity of anthropometric values for the same fat value. However, predictive equations based on a large sample size, while exhibiting no current difference in variances, can show a shift in mean values. This mean-shift is the result of differences in DXA devices and needs to be corrected. It means that DXA values from a few individuals in the population under study must be obtained to calculate a corrective factor.

Pancreatic Steatosis Is Associated with Both Metabolic Syndrome and Pancreatic Stiffness Detected by Ultrasound Elastography.

INTRODUCTION: There is increasing evidence that pancreatic steatosis (PS) is associated with metabolic syndrome (MS). However, it is not known whether it is associated with PS grade and pancreatic stiffness, or not. We aimed to evaluate the relationship between PS and its grade detected by transabdominal ultrasound, and pancreatic stiffness determined by two-dimensional shearwave elastography (2D-SWE), whether it has clinical significance and its relationship with MS. METHODS: Patients with and without PS were evaluated prospectively. RESULTS: Patients with PS had higher odds ratio for MS (OR 5.49). Also, ultrasonographic grade of PS was associated with MS parameters and hepatosteatosis. Pancreatic SWE value was significantly higher in PS group and positively correlated with PS grade, liver fat, MS, number of MS criteria. DISCUSSION/CONCLUSION: PS and its grade were associated with MS. In this first comprehensive PS-SWE study, we found that pancreas stiffness increased in the presence of PS, in correlation with PS grade and MS.

Aging and changes in adiposity indices: the impact of menopause.

PURPOSE: Aging is associated with significant changes in fat distribution and menopause may alter this process. This study aimed to investigate the longitudinal effect of menopause on changes in adiposity indices (AI). METHODS: A total number of 3876 non-menopausal women, aged > 20 years, who participated in the Tehran Lipid and Glucose study, were selected for the present study. They were followed from 1998 to 2018 at a 3-year interval and their adiposity indices were measured. Throughout the study, participants were categorized into two groups according to their menopausal status as group 1): women who reached menopause and group 2): women who did not reach menopause. The generalized estimation equation (GEE) models were used to compare the trend of changes in AIs between these two groups. RESULTS: At the end of the study, a total number of 1479 (38.2%) participants reached menopause. The odds of general obesity decreased by 5% (OR: 0.95, 95% CI: 0.90-0.99), and the odds of central obesity increased by 6% in group1 compared to group2 (OR: 1.06, 95% CI: 1.01-1.12). CONCLUSIONS: Menopause alters the impact of aging on central fat distribution. Increasing awareness of the related risk in menopausal women and their healthcare professional may prevent adverse related outcomes.

Nonalcoholic Fatty Pancreas Disease: Role in Metabolic Syndrome, "Prediabetes," Diabetes and Atherosclerosis.

Fat accumulation in the pancreas associated with obesity and the metabolic syndrome (MetS) has been defined as "non-alcoholic fatty pancreas disease" (NAFPD). The aim of this review is to describe the association of NAFPD with obesity, MetS, type 2 diabetes mellitus (T2DM) and atherosclerosis and also increase awareness regarding NAFPD. Various methods are used for the detection and quantification of pancreatic fat accumulation that may play a significant role in the differences that have been observed in the prevalence of NAFPD. Endoscopic ultrasound provides detailed images of the pancreas and its use is expected to increase in the future. Obesity and MetS have been recognized as NAFPD risk factors. NAFPD is strongly associated with non-alcoholic fatty liver disease (NAFLD) and it seems that the presence of both may be related with aggravation of NAFLD. A role of NAFPD in the development of "prediabetes" and T2DM has also been suggested by most human studies. Accumulation of fat in pancreatic tissue possibly initiates a vicious cycle of beta-cell deterioration and further pancreatic fat accumulation. Additionally, some evidence indicates a correlation between NAFPD and atherosclerotic markers (e.g., carotid intima-media thickness). Weight loss and bariatric surgery decreases pancreatic triglyceride content but pharmacologic treatments for NAFPD have not been evaluated in specifically designed studies. Hence, NAFPD is a marker of local fat accumulation possibly associated with beta-cell function impairment, carbohydrate metabolism disorders and atherosclerosis.

Comparison of pancreatic fat content measured by different methods employing MR mDixon sequence.

OBJECTIVE: To compare the reliability of different methods for measuring fat content of pancreas by MR modified Dixon(mDixon) Sequence and accurately evaluate pancreatic fat in as simple a way as possible. METHODS: This is a retrospective study, 64 patients were included in this study who underwent abdominal MR scan that contained the mDixon sequence from June 2019 to May 2020(Included 7 patients with type 2 diabetes and 4 patients with impaired glucose tolerance (IGT), they were admitted to hospital through the obesity clinic set up by endocrine department, all of them were initially diagnosed and untreated). All of the 64 patients were scanned in 3.0T MR (Philips Ingenia II) due to their condition, 10-34 slice pancreas images were obtained, which were different from each other. Three different methods of measurement were employed by two observers using Philips Intellispace Portal software: (1) All images (whole-pancreas) measurement, the whole-pancreatic fat fraction (wPFF) was calculated by software. (2) Interval slices measurement, that is half-pancreatic slices fat fraction (hPFF) measured in the same way, fat fraction obtained by the interlayer assay was calculated. (3) As usual, the fat content of pancreatic head, body and tail fat was measured respectively, and in order to improve credibility, we also measured head、 body and tail in every layer, and its average value was taken. The elapsed time of the above different measurement methods was recorded. Intra-group correlation coefficient (ICC) was used to analyze the consistency of the measured data within and between observers. T-tests and Friedman tests were applied to compare the difference of measured values among groups. RESULTS: No matter in normal person or diabetic or IGT, hPFF has shown good stability (ICChPFF = 0.988), and there was no significant difference compared with wPFF. But the average fat percentage composition of head, body and tail were significantly different from wPFF and hPFF (P < 0.01). At the same time, compared with normal person, pancreatic fat content in IGT and diabetic patients showed progressive significance(P<0.05). CONCLUSION: The distribution of pancreatic fat is not uniform, the method of measuring half pancreas by interlayer data collection can reflect the fat content of the entire pancreas, this suggests that measuring 50% of the pancreas is sufficient, this method effectively saves time and effort without affecting the results, which may have a better clinical application prospect.

White adipose tissue dysfunction in obesity and aging.

Both obesity and aging are associated with the development of metabolic diseases such as type 2 diabetes and cardiovascular disease. Chronic low-grade inflammation of adipose tissue is one of the mechanisms implicated in the progression of these diseases. Obesity and aging trigger adipose tissue alterations that ultimately lead to a pro-inflammatory phenotype of the adipose tissue-resident immune cells. Obesity and aging also share other features such as a higher visceral vs. subcutaneous adipose tissue ratio and a decreased lifespan. Here, we review the common characteristics of obesity and aging and the alterations in white adipose tissue and resident immune cells. We focus on the adipose tissue metabolic derangements in obesity and aging such as inflammation and adipose tissue remodeling.

Estimation of the marbling development pattern in Japanese Black cattle by using serial ultrasound measurement data.

The objective of this study was to develop mathematical equations for describing the change in marbling in Japanese Black steers using longitudinal measurements. Serial ultrasound measurements were taken at 14, 16, 20, and 26 months of age and analyzed using an image analysis software. The longitudinal marbling measurements from the ultrasound images and carcasses were fitted into a nonlinear logistic curve. Data used for the analysis consisted of 749 steers that converged in nonlinear curve fitting and showed reasonable estimated parameters of the logistic curves. The average predicted mature beef marbling score (BMS) and maturation rate were 6.26 and 0.353, respectively, and the average maturity levels at 24 months of age were 83.9%. The heritability estimates for the predicted maturity traits were moderate, indicating that these traits may have potential for genetic improvement. There was a negative relationship between the expected progeny differences between carcass BMS and maturity traits, suggesting that genetic improvement by carcass BMS may lead to the selection of bulls with late maturity for marbling. The results indicate that ultrasound and model building for marbling can be useful tools to correctly select candidate bulls with high marbling in the early fattening period.

Comparative analysis of BIA, IBC and DXA for determining body fat in American Football players.

BACKGROUND: Body composition is frequently measured by sports, fitness, and healthcare professionals. Dual-Energy X-ray Absorptiometry (DXA) analysis is a validated measurement of body composition and is considered a criterion or "gold-standard" measurement. However, due to long scan times, accessibility and cost, conducting DXA scans on larger athletes (i.e., football players) is difficult. Hence fitness professionals, notably strength and conditioning coaches, typically use other methods to measure body composition. The aim of this study was to assess the accuracy of the Bioelectrical Impedance Analysis (BIA) and Integrative Body Composition (IBC) techniques to DXA body fat percent (BF%) in collegiate American Football players. METHODS: Participants performed all three modes of body composition measurement: DXA, BIA (BIA-A [athlete]and BIA-NA [non-athlete modes]), and IBC, on the same day during early morning hours in a fasted state. RESULTS: The BF% measured via all methods significantly correlated with BF% measured via DXA (i.e., BIA-A [P<0.001, r=0.903], BIA-NA [P<0.001, r=0.891], and IBC [P<0.001, r=0.867]). However, values obtained via BIA-A (athlete) (P<0.001) and IBC (P<0.001) methods under predicted BF%. CONCLUSIONS: BIA and IBC can be used as an alternative to DXA for measuring BF% in American Football players. The BIA-A and IBC under predicted BF% compare to DXA, therefore, a correction formula can be utilized by coaches and athletes to predict BF% more accurately compared to IBC and BIA-A methods in American Football players.

Evaluation of the body adiposity index against dual-energy X-ray absorptiometry for assessing body composition in children and adolescents.

BACKGROUND: It is important to clarify the association of lean and fat mass between children and adolescents considering the rising prevalence of overweight and obesity in this age group. The aim of this study was to verify the association between the body adiposity index (BAI) and dual-energy X-ray absorptiometry (DXA) methods for analyzing body composition, as well as analyzing the validity of BAI to verify the percentage of fat in children and adolescents. METHODS: The sample was composed of 106 children and adolescents, 44 females (age: 11.5 ± 1.8 years) and 62 evils (13.6 ± 2.6 years). The body fat (%F) was measured using DXA and the doubly indirect BAI body fat estimation technique. RESULTS: The BAI and DXA estimates of %F were strongly correlated (boys: r = .71, P < .0001; girls: r = .72, P < .0001). The linear regression analyses showed that BAI is significant to estimate the %F in total sample (P < .0001). For boys, the %F analyzes performed by BAI and DXA did not show any differences when compared (P = .2). In addition, BAI pointed out a significant proportion bias for both sexes (P < .0001), which suggests its inefficiency in the analysis of %F. CONCLUSIONS: BAI and DXA correlate; however, there is low reliability and a high proportion bias for the analysis of %F by BAI.

Relationships of Physical Activity and Diet Quality with Body Composition and Fat Distribution in US Adults.

OBJECTIVE: This study aimed to investigate the relationships among physical activity (PA), diet quality, body composition, and fat distribution in a representative sample of US adults. METHODS: A cross-sectional analysis was conducted using publicly accessible data from the 2011 to 2016 National Health and Nutrition Examination Survey and the Food Patterns Equivalents Database (n = 7,423). Variables from the data sets were analyzed for this study, including PA, two 24-hour dietary recalls, and dual-energy x-ray absorptiometry outputs. RESULTS: For men, PA and diet quality were inversely associated with the percentage of body fat (ß = -0.0042, 95% CI: -0.0084 to -0.0001; ß = -0.28, 95% CI: -0.42 to -0.14) and fat mass index (ß = -0.0125, 95% CI: -0.0209 to -0.0041; ß = -0.56, 95% CI: -0.81 to -0.32); meeting the PA recommendation and having good diet quality provided an additive effect on body fat. A similar pattern was observed in women. Additionally, diet quality was inversely associated with all fat distribution measures in both sexes, whereas PA was positively associated with lean mass measures in men only. CONCLUSIONS: Increased PA and/or better diet quality were associated with reduced body fat, a healthier fat distribution, and increased lean mass. Further research examining how changes in PA or diet quality influence body composition and fat distribution in adults is warranted.

RNA-Seq based genetic variant discovery provides new insights into controlling fat deposition in the tail of sheep.

Genetic basis of fat deposition in sheep tail have not been completely elucidated yet. Understanding the genetic mechanisms controlling fat-tail size can improve breeding strategies to modulate fat deposition. RNA sequencing has made it possible to discover genetic variants that may underlie various phenotypic differences. Hence, to identify genetic variants that are important for describing different fat-tail phenotypes in sheep, RNA sequencing was used for single nucleotide polymorphism (SNP) calling in two Iranian sheep breeds (Lori-Bakhtiari, fat-tailed; n = 4, vs Zel, thin-tailed; n = 4). Using a stringent pipeline, a total of 112,344 known SNPs were genotyped, of which 30,550 and 42,906 SNPs were shared by at least two Lori-Bakhtiari and Zel, respectively. Comparing these SNPs showed 2,774 (including 209 missense and 25 deleterious SNPs) and 10,470 (including 1,054 missense and 116 deleterious SNPs) breed-specific SNPs in Lori-Bakhtiari and Zel sheep, respectively. Potential breed-specific SNPs were detected by considering those located in QTL regions associated with fatness or reported as important candidates in previous similar studies. Of the breed-specific SNPs, 724 and 2,905 were located in the QTL regions. Functional enrichment analysis of the affected genes revealed several enriched gene ontologies and KEGG pathways related to fat metabolism. Based on the results, several affected genes were proposed to be strongly linked with fat deposition such as DGAT2, ACSL1, ACACA, ADIPOQ, ACLY, FASN, CPT2, SCD, ADCY6, PER3, CSF1R, SLC22A4, GFPT1, CDS2, BMP6, ACSS2, ELOVL6, HOXA10 and FABP4. Moreover, several SNPs were found in the candidate genes related to fatty acid oxidation introducing them as promising candidates responsible for lower fat content in tail of Zel. Our findings provided new insights into the genetic mechanisms of fat deposition in sheep, which can serve to designing appropriate breeding programs.

In Vivo Investigation of High-Fat Diet-Induced Hepatic Lipid Dysfunctions.

Fat distribution, on top of general obesity, contributes to the severity of histologic features in patients with nonalcoholic fatty liver diseases (NAFLD); and visceral obesity has been correlated to fatty liver diseases. Therefore, investigation of fat distribution in vivo could be a good predictor of fatty liver risks in obesity. Fatty acids composition is a key player in hepatic dysfunctions and cardiovascular risk in obesity. Because fatty acids can damage biological membranes, fatty acid accumulation in the liver may be partially responsible for the functional and morphological changes that are observed in NAFLD. Fatty acids stored into triglycerides are lipid species that act as signaling molecules and therefore are key regulators of posttranslational regulation of biological functions such as lipid homeostasis and lipotoxicity. Here, we describe magnetic resonance methods to investigate in vivo whole-body fat distribution and hepatic liver fatty acid composition in order to directly assess the liver metabolic status and may allow to anticipate liver diseases.

Adipose tissue morphology, imaging and metabolomics predicting cardiometabolic risk and family history of type 2 diabetes in non-obese men.

We evaluated the importance of body composition, amount of subcutaneous and visceral fat, liver and heart ectopic fat, adipose tissue distribution and cell size as predictors of cardio-metabolic risk in 53 non-obese male individuals. Known family history of type 2 diabetes was identified in 25 individuals. The participants also underwent extensive phenotyping together with measuring different biomarkers and non-targeted serum metabolomics. We used ensemble learning and other machine learning approaches to identify predictors with considerable relative importance and their intricate interactions. Visceral fat and age were strong individual predictors of ectopic fat accumulation in liver and heart along with markers of lipid oxidation and reduced glucose tolerance. Subcutaneous adipose cell size was the strongest individual predictor of whole-body insulin sensitivity and also a marker of visceral and ectopic fat accumulation. The metabolite 3-MOB along with related branched-chain amino acids demonstrated strong predictability for family history of type 2 diabetes.

Obesity and Overactive Bladder: Is It a Matter of Body Weight, Fat Distribution or Function? A Preliminary Results.

OBJECTIVE: To determine the relationship between subcutaneous fat, visceral fat surface area (VFA), bladder wall fat distribution, and visceral adiposity index (VAI) as risk factors for overactive bladder (OAB) occurrence. PATIENTS AND METHODS: A cross-sectional study involved 157 participants was conducted. The participants were divided into 2 groups; study group (87 patients diagnosed with OAB) and control group (70 healthy participants). All participants were evaluated for OAB using short-form OABSS version. Physical examination including waist circumference (WC) measurement in addition to metabolic laboratory investigations (eg, High density lipoprotein (HDL), cholesterol, etc) were done. Study group underwent urodynamic testing. Using noncontrast spiral CT abdomen and pelvis, trunkal fat measurements and bladder wall fat distribution were detected. VAI was calculated for both females and males. Univariate and multivariate analyses were done to detect risk factors for OAB occurrence. Correlation between all factors and total OABSS and urodynamics was done. RESULTS: The mean age ± SD was 40.4 ± 9 years. In multivariate analysis, increased VFA, higher cholesterol level, increased VAI and focal fat distribution at bladder wall were associated with 9.4, 1.98, 5.5, and 1.6 times higher risk for OAB occurrence. VAI and VFA were strongly correlated with total OABSS, DLPP, amplitude, and frequency of bladder detrusor contractions. On the other hand, WC and body mass index were not correlated significantly. CONCLUSION: Body mass index and WC are crude inaccurate methods correlated with OAB presence. Focal bladder wall fat distribution, higher VAI, higher VFA are novel risk factors for OAB occurrence. Both VAI and VFA are correlated significantly to total OABSS and urodynamics findings in patients with OAB.

Titrating Growth Hormone Dose to High-Normal IGF-1 Levels Has Beneficial Effects on Body Fat Distribution and Microcirculatory Function Despite Causing Insulin Resistance.

To clarify the mechanism underlying the described U-shaped relation of both low and high levels of IGF-1 with cardiovascular disease this study explores the effect of decreasing and increasing growth hormone dose in GH deficient adults on (micro)vascular function, body composition and insulin resistance. In this randomized clinical trial, thirty-two subjects receiving GH therapy with an IGF-1 concentration between -1 and 1 SD score (SDS) for at least one year were randomized to receive either a decrease (IGF-1 target level of -2 to -1 SDS) or an increase of their daily GH dose (IGF-1 target level of 1 to 2 SDS) for a period of 24 weeks. Microvascular endothelium (in)dependent vasodilatation and vasomotion, vascular stiffness by pulse wave analysis, and HOMA-IR were measured. At the end of the study 30 subjects (65.6% men, mean age 46.6 (SD 9.9) years) were analyzed. There was a favorable effect of increasing the IGF-1 level on waist circumference compared to decreasing the IGF-1 level (p=0.05), but a detrimental effect on insulin resistance (p=0.03). Decreasing IGF-1 level significantly lowered the endothelial domain of vasomotion (p=0.03), whereas increasing IGF-1 level increased the contribution of the neurogenic domain (p=0.05). This change was related to the favorable change in waist circumference. In conclusion, increasing IGF-1 levels was beneficial for body composition but detrimental with respect to insulin resistance. The contribution of the neurogenic vasomotion domain increased in parallel, and could be explained by the favorable change in waist circumference. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT01877512.

The comparison of percent body fat estimated by different anthropometrics to predict the incidence of hypertension.

Percent body fat (%BF) is associated with the development of hypertension. However, the power of %BF estimated by different anthropometrics to predict incident hypertension was unknown. This study was from the China Health and Nutrition Survey (CHNS). %BF was calculated using the equations with BMI, WC, and skinfold thickness and divided into low and high %BF according to ROC. Cox regression was employed to evaluate the power of different %BFs to predict the development of hypertension. When not adjusting for covariates, %BFs defined by BMI, WC, and ST were the significant predictors of the development of hypertension (all P < 0.0001; crude HR: 2.238, 3.243, and 1.574; and HR 95% CI: 2.098-2.387, 2.905-3.619, and 1.464-1.692). When three %BFs entered into model simultaneously, the significance in %BF estimated by ST disappeared (P = 0.0765; adjusted HR: 1.124; and HR 95% CI: 0.988-1.280). For males, %BFs by BMI, WC, and ST significantly affected the incidence of hypertension as they were separately analyzed (all P < 0.0001; crude HR: 2.445, 2.335, and 1.828; and HR 95% CI: 2.220-2.693, 2.011-2.712, and 1.636-2.042, respectively). For females, %BFs estimated by BMI, WC, and ST were the determinants of the development of hypertension whether covariates were adjusted or not (all P < 0.0001). In conclusion, there was a poor and ineffective association of %BF estimated by triceps skinfold thickness with the development of hypertension, especially when three %BFs were analyzed together. High %BFs estimated by BMI and WC were the true and effective predictors of the incidence of hypertension.

Prediction of Circulating Adipokine Levels Based on Body Fat Compartments and Adipose Tissue Gene Expression.

BACKGROUND: Adipokines are hormones secreted from adipose tissue (AT), and a number of them have been established as risk factors for chronic diseases. However, it is not clear whether and to what extent adiposity, gene expression, and other factors determine their circulating levels. OBJECTIVES: To assess to what extent adiposity, as measured by the amount of subcutaneous AT (SAT) and visceral AT (VAT) using magnetic resonance imaging, and gene expression levels in SAT determine plasma concentrations of the adipokines adiponectin, leptin, soluble leptin receptor, resistin, interleukin 6, and fatty acid-binding protein 4 (FABP4). METHODS: We performed a cross-sectional analysis of 156 participants from the EPIC Potsdam cohort study and analyzed multiple regression models and partial correlation coefficients. RESULTS: For leptin and FABP4 concentrations, 81 and 45% variance were explained by SAT mass, VAT mass, and gene expression in SAT in multivariable regression models. For the remaining adipokines, AT mass and gene expression explained <16% variance of plasma concentrations. Gene expression in SAT was a less important predictor compared to AT mass. SAT mass was a better predictor than VAT mass for leptin (partial correlation r = 0.81, 95% confidence interval 0.75-0.86, vs. r = 0.58, 95% confidence interval 0.46-0.67), while differences between AT compartments were small for the other adipokines. CONCLUSIONS: While plasma levels of leptin and FABP4 can be explained in a large and medium part by the amount of AT and SAT gene expression, surprisingly, these predictors explained only little variance for all other investigated adipokines.

Quantification of intrathoracic fat adds prognostic value in women undergoing myocardial perfusion imaging.

AIM: Amongst patients with coronary artery disease (CAD), women experience relatively worse outcomes as compared to men. Evidence to date has failed to explore unique female imaging targets as major determinants of cardiovascular risk. We sought to assess the prognostic value of epicardial (EFV) and intrathoracic fat volume (IFV) quantification in women and men with suspected and known CAD. METHODS AND RESULTS: Intrathoracic fat volume and EFV were calculated from non-contrast CT and analyzed in a propensity-matched cohort of 190 patients (95 women, mean age 62.5 ±â€¯11.3 years) undergoing myocardial perfusion imaging (MPI) and coronary computed tomography angiography (CCTA) for evaluation of CAD. IFV and EFV were significantly lower in women as compared to men (198.2 ±â€¯78.4 vs 293.2 ±â€¯114.7 cm3 and 105.6 ±â€¯48.9 vs 135.8 ±â€¯60.9 cm3, p < 0.001) and showed a strong association with coronary artery calcium score (CACS) and obstructive CAD in women (p < 0.05), but not in men. Fat volumes were not related to abnormal MPI in either population (p = NS). During a median follow-up of 2.8 years, high IFV was associated with reduced event free survival (log rank = 0.019 vs low IFV) in women, but not in men. Accordingly, a multivariate Cox regression model adjusted for cardiovascular risk factors, CACS, CCTA, and MPI findings selected IFV as a significant predictor of major adverse cardiovascular events (MACE) in women (HR 1.32, 95%CI 1.18-1.55, p = 0.001). CONCLUSION: Quantification of IFV provides incremental prognostic value for MACE in women, beyond that provided by traditional risk factors and imaging findings.

CT-Quantified Adipose Tissue Distribution: Risk or Protective Factor for Complications after Rectal Cancer Surgery?

PURPOSE: Obesity is associated with increased incidence and mortality in rectal cancer (RC). However, an obesity paradox in the sense of a protective effect of obesity is discussed controversially. We evaluated whether adipose tissue distribution has an impact on medical (MC) and surgical complications (SC) after RC surgery. METHODS: A total of 296 RC patients underwent oncological surgery and multidetector CT with quantification of total (TAT), visceral (VAT), and subcutaneous adipose tissue (SAT). Logistic regressions on SC (anastomotic leakage [n = 26], wound infection [n = 58], bleeding [n = 12], abscess [n = 32], bladder dysfunction [n = 24], burst abdomen [n = 10]), and MC (pulmonary [n = 22], cardiac [n = 18], urinary tract infection [n = 9], sepsis [n = 5]) were performed. RESULTS: High pelvicVAT was associated with reduced risk for overall SC (OR = 0.915, p = 0.012) and anastomotic leakage (OR = 0.587, p = 0.024, CI: 0.369/0.934). In contrast, CT-quantified obesity was associated with increased risk for wound infection, bladder dysfunction, burst abdomen, overall MC, and cardiac complications (ORs up to 1.423). BMI was not associated with any SC or MC. CONCLUSION: An obesity paradox with a protective effect of CT-quantified adipose tissue was confirmed for anastomotic leakage and overall SC. In contrast, high adipose tissue was associated with higher risk for other SC and MC. These results show a more complex influence of body composition on MC and SC. CT-quantified obesity is able to provide deeper insights to explain the obesity paradox beyond BMI.