Ethnic and sex differences in fatty liver on cardiac computed tomography: the multi-ethnic study of atherosclerosis

Structural and social determinants of health: The multi-ethnic study of atherosclerosis

BACKGROUND

Researchers have increasingly recognized the importance of structural and social determinants of health (SSDOH) as key drivers of a multitude of diseases and health outcomes. The Multi-Ethnic Study of Atherosclerosis (MESA) is an ongoing, longitudinal cohort study of subclinical cardiovascular disease (CVD) that has followed geographically and racially/ethnically diverse participants starting in 2000. Since its inception, MESA has incorporated numerous SSDOH assessments and instruments to study in relation to CVD and aging outcomes. In this paper, we describe the SSDOH data available in MESA, systematically review published papers using MESA that were focused on SSDOH and provide a roadmap for future SSDOH-related studies.

METHODS AND FINDINGS

The study team reviewed all published papers using MESA data (n = 2,125) through January 23, 2023. Two individuals systematically reviewed titles, abstracts, and full text to determine the final number of papers (n = 431) that focused on at least one SSDOH variable as an exposure, outcome, or stratifying/effect modifier variable of main interest (discrepancies resolved by a third individual). Fifty-seven percent of the papers focused on racialized/ethnic groups or other macrosocial/structural factors (e.g., segregation), 16% focused on individual-level inequalities (e.g. income), 14% focused on the built environment (e.g., walking destinations), 10% focused on social context (e.g., neighborhood socioeconomic status), 34% focused on stressors (e.g., discrimination, air pollution), and 4% focused on social support/integration (e.g., social participation). Forty-seven (11%) of the papers combined MESA with other cohorts for cross-cohort comparisons and replication/validation (e.g., validating algorithms).

CONCLUSIONS

Overall, MESA has made significant contributions to the field and the published literature, with 20% of its published papers focused on SSDOH. Future SSDOH studies using MESA would benefit by using recently added instruments/data (e.g., early life educational quality), linking SSDOH to biomarkers to determine underlying causal mechanisms linking SSDOH to CVD and aging outcomes, and by focusing on intersectionality, understudied SSDOH (i.e., social support, social context), and understudied outcomes in relation to SSDOH (i.e., sleep, respiratory health, cognition/dementia).

Association of disproportionate liver fat with markers of heart failure: The multi-ethnic study of atherosclerosis

BACKGROUND

Metabolic dysfunction associated steatotic liver disease (MASLD) has been linked to heart failure with preserved ejection fraction (HFpEF). We sought to understand association between individuals with amounts of liver adiposity greater than would be predicted by their body mass index (BMI) in order to understand whether this disproportionate liver fat (DLF) represents a proxy of metabolic risk shared between liver and heart disease.

METHODS

We studied 2,932 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) who received computed tomography (CT) measurements of hepatic attenuation. Quartiles of DLF were compared and multivariable linear regression was performed to evaluate the association of DLF with clinical, echocardiographic, and quality of life metrics.

RESULTS

Compared to the lowest quartile of DLF, individuals in the highest quartile of DLF were more likely to be male (52.0% vs 47.1%, P < .001), less likely to be Black or African American (14.8 % vs 38.1% P < .001), have higher rates of dysglycemia (31.9% vs 16.6%, P < .001) and triglycerides (140 [98.0, 199.0] vs 99.0 [72.0, 144.0] mg/dL, P > .001). These individuals had lower global longitudinal strain (-0.13 [-0.25, -0.02], P = .02), stroke volumes (-1.05 [-1.76, -0.33], P < .01), lateral e' velocity (-0.10 [-0.18, -0.02], P = .02), and 6-minute walk distances (-4.25 [-7.62 to -0.88], P = .01).

CONCLUSION

DLF is associated with abnormal metabolic profiles and ventricular functional changes known to be associated with HFpEF and may serve as an early metric to assess for those that may progress to clinical HFpEF.

Non-Hispanic Black Persons With Nonalcoholic Fatty Liver Disease Have Lower Rates of Advanced Fibrosis, Cirrhosis, and Liver-Related Events Even After Controlling for Clinical Risk Factors and PNPLA3 Genotype

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is less frequent in non-Hispanic persons (NHB), but there are knowledge gaps in our understanding of disease severity and outcomes of NAFLD in NHB. We compared liver histology and clinical outcomes of NAFLD in non-Hispanic Black persons (NHB) and non-Hispanic White persons (NHW).

METHODS

We compared liver histology and outcomes of 109 NHB and 1,910 NHW adults with biopsy-proven NAFLD participating in the Nonalcoholic Steatohepatitis Clinical Research Network observational studies. The relationship between self-reported NHB race/ethnicity and advanced fibrosis was assessed through multivariable logistic regression after controlling for clinical covariates and PNPLA3 genotype.

RESULTS

NHB and NHW with NAFLD had similar NAFLD activity scores (NAS, 4.4 vs 4.3, P = 0.87) and proportions with definite metabolic dysfunction-associated steatohepatitis (59% vs 58%, P = 1.0), but NHB had significantly lower rates of advanced fibrosis (22% vs 34%, P = 0.01) or cirrhosis (4.6% vs 12.1%, P = 0.010). Compared with NHW, NHB had significantly lower frequency of advanced fibrosis (Odds Ratio: 0.48, 95% Confidence Interval: 27-0.86, P = 0.01). In a comparison between 24 NHB and 655 NHW with advanced fibrosis, the NAS (5.6 vs 4.9, P = 0.01) and lobular inflammation grade (2.2 vs 1.7, P < 0.002) were significantly higher among NHB with advanced fibrosis. One NHB and 23 NHW died during follow-up (0.30 vs 0.28 per 100 person-year follow-up). Seven and zero liver-related deaths occurred in NHW and NHB with NAFLD, respectively.

DISCUSSION

The risk of advanced fibrosis in NHB with NAFLD is significantly lower, after controlling for clinical risk factors and PNPLA3 genotype. Although their risk of advanced fibrosis was low, NHB with NAFLD and advanced fibrosis had higher NAS and lobular inflammation, indicating a difference in their relationship between necroinflammation and fibrosis.

Observational and genetic association of non-alcoholic fatty liver disease and calcific aortic valve disease

Background

Non-alcoholic fatty liver disease (NAFLD) has emerged as a predominant driver of chronic liver disease globally and is associated with increased cardiovascular disease morbidity and mortality. However, the association between NAFLD and calcific aortic valve disease remains unclear. We aimed to prospectively investigate the association between NAFLD and incident aortic valve calcification (AVC), as well as its genetic relationship with incident calcific aortic valve stenosis (CAVS).

Methods

A post hoc analysis was conducted on 4226 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) database. We employed the adjusted Cox models to assess the observational association between NAFLD and incident AVC. Additionally, we conducted two-sample Mendelian randomization (MR) analyses to investigate the genetic association between genetically predicted NAFLD and calcific aortic valve stenosis (CAVS), a severe form of CAVD. We repeated the MR analyses by excluding NAFLD susceptibility genes linked to impaired very low-density lipoprotein (VLDL) secretion.

Results

After adjustment for potential risk factors, participants with NAFLD had a hazard ratio of 1.58 (95% CI: 1.03-2.43) for incident AVC compared to those without NAFLD. After excluding genes associated with impaired VLDL secretion, the MR analyses consistently showed the significant associations between genetically predicted NAFLD and CAVS for 3 traits: chronic elevation of alanine aminotransferase (odds ratio = 1.13 [95% CI: 1.01-1.25]), imaging-based NAFLD (odds ratio = 2.81 [95% CI: 1.66-4.76]), and biopsy-confirmed NAFLD (odds ratio = 1.12 [95% CI: 1.01-1.24]). However, the association became non-significant when considering all NAFLD susceptibility genes.

Conclusions

NAFLD was independently associated with an elevated risk of incident AVC. Genetically predicted NAFLD was also associated with CAVS after excluding genetic variants related to impaired VLDL secretion.

Effect of a Higher-Protein Nut versus Higher-Carbohydrate Cereal Enriched Diet on the Gut Microbiomes of Chinese Participants with Overweight and Normoglycaemia or Prediabetes in the Tū Ora Study

Global increases in metabolic disorders such as type 2 diabetes (T2D), especially within Asian populations, highlight the need for novel approaches to dietary intervention. The Tū Ora study previously evaluated the effects on metabolic health of including a nut product into the diet of a New Zealand cohort of Chinese participants with overweight and normoglycaemia or prediabetes through a 12-week randomised, parallel-group clinical trial. In this current study, we compared the impact of this higher-protein nut bar (HP-NB) versus a higher-carbohydrate cereal bar (HC-CB) on the faecal microbiome by employing both 16S rRNA gene amplicon and shotgun metagenomic sequencing of pre- and post-intervention pairs from 84 participants. Despite the higher fibre, protein, and unsaturated fat content of nuts, there was little difference between dietary groups in gut microbiome composition or functional potential, with the bacterial phylum Firmicutes dominating irrespective of diet. The lack of observed change suggests the dietary impact of the bars may have been insufficient to affect the gut microbiome. Manipulating the interplay between the diet, microbiome, and metabolic health may require a more substantial and/or prolonged dietary perturbation to generate an impactful modification of the gut ecosystem and its functional potential to aid in T2D risk reduction.

Prognostic value of metabolic dysfunction-associated steatotic liver disease over coronary computed tomography angiography findings: comparison with no-alcoholic fatty liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the proposed name change for non-alcoholic fatty liver disease (NAFLD). This study aimed to investigate the association of cardiovascular disease risk with MASLD and NAFLD in patients who underwent clinically indicated coronary computed tomography angiography (CCTA).

METHODS

This retrospective study included 2289 patients (60% men; mean age: 68 years) with no history of coronary artery disease who underwent CCTA. The steatotic liver was defined as a hepatic-to-spleen attenuation ratio of < 1.0 on CT just before CCTA. MASLD is defined as the presence of hepatic steatosis along with at least one of the five cardiometabolic risk factors. Adverse CCTA findings were defined as obstructive and/or high-risk plaques. Major adverse cardiac events (MACE) encompassed composite coronary events, including cardiovascular death, acute coronary syndrome, and late coronary revascularization.

RESULTS

MASLD and NAFLD were identified in 415 (18%) and 368 (16%) patients, respectively. Adverse CCTA findings were observed in 40% and 38% of the patients with MASLD and with NAFLD, respectively. Adverse CCTA findings were significantly associated with MASLD (p = 0.007) but not NAFLD (p = 0.253). During a median follow-up of 4.4 years, 102 (4.4%) MACE were observed. MASLD was significantly associated with MACE (hazard ratio 1.82, 95% CI 1.18-2.83, p = 0.007), while its association with NAFLD was not significant (p = 0.070). By incorporating MASLD into a prediction model of MACE, including the risk score and adverse CCTA findings, global chi-squared values significantly increased from 87.0 to 94.1 (p = 0.008).

CONCLUSIONS

Patients with MASLD are likely to have a higher risk of cardiovascular disease than those with NAFLD. Concurrent assessment of MASLD during CCTA improves the identification of patients at a higher risk of cardiovascular disease among those with clinically indicated CCTA.

The association between hepatic steatosis and incident cardiovascular disease, cancer, and all-cause mortality in a US multicohort study

BACKGROUND AND AIMS

NAFLD strongly associates with cardiovascular disease (CVD) risk factors; however, the association between NAFLD and incident CVD, CVD-related mortality, incident cancer, and all-cause mortality is unclear.

APPROACH AND RESULTS

We included 10,040 participants from the Framingham Heart Study, the Coronary Artery Risk Development in Young Adults Study, and the Multi-ethnic Study of Atherosclerosis to assess the longitudinal association between liver fat (defined on CT) and incident CVD, CVD-related mortality, incident cancer, and all-cause mortality. We performed multivariable-adjusted Cox regression models including age, sex, diabetes, systolic blood pressure, alcohol use, smoking, HDL, triglycerides, and body mass index at baseline or time-varying covariates. The average age was 51.3±3.3 years and 50.6% were women. Hepatic steatosis was associated with all-cause mortality after 12.7 years of mean follow-up when adjusting for baseline CVD risk factors, including body mass index (HR: 1.21, 1.04-1.40); however, the results were attenuated when utilizing time-varying covariates. The association between hepatic steatosis and incident CVD was not statistically significant after we accounted for body mass index in models considering baseline covariates or time-varying covariates. We observed no association between hepatic steatosis and CVD-related mortality or incident cancer.

CONCLUSIONS

In this large, multicohort study of participants with CT-defined hepatic steatosis, accounting for change in CVD risk factors over time attenuated associations between liver fat and overall mortality or incident CVD. Our work highlights the need to consider concurrent cardiometabolic disease when determining associations between NAFLD and CVD and mortality outcomes.

Prognostic Value of Nonalcoholic Fatty Liver Disease in Patients With Severe Aortic Stenosis Who Underwent Transcatheter Aortic Valve Implantation

Nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of cardiovascular events. Although the association between NAFLD and aortic valve sclerosis has been described, the prevalence and prognostic implications of NAFLD among patients with severe aortic stenosis (AS) have not been described. In addition, the effect of the presence of severe tricuspid regurgitation (TR) on the prevalence of NAFLD remains unexplored. Accordingly, we investigated the prognostic implications of NAFLD among patients with severe AS with and without concomitant significant TR. A total of 538 patients (aged 80 ± 7 y, 49.6% men) who underwent noncontrast computed tomography before transcatheter aortic valve implantation (TAVI) between 2007 and 2019 were included. NAFLD was defined as a liver-to-spleen attenuation ratio <1.0 on noncontrast computed tomography. NAFLD was present in 118 patients (21.9%). There were no significant differences in pulmonary arterial pressure, right atrial pressure, or the prevalence of significant TR between patients with and without NAFLD. During a median follow-up of 47 months (interquartile range 20 to 70 months), 224 patients (41.6%) died. Univariate Cox regression analysis demonstrated that NAFLD was not significantly associated with all-cause death among patients treated with TAVI (hazard ratio 1.32, 95% confidential interval 0.97 to 1.79, p = 0.07). In conclusion, among patients with severe AS who underwent TAVI, the prevalence of significant TR and the clinical outcomes were similar in patients with and without NAFLD.

Relationship of American Heart Association's Life Simple 7, Ectopic Fat, and Insulin Resistance in 5 Racial/Ethnic Groups

BACKGROUND

The inverse association between ideal cardiovascular health (CVH) as measured by the American Heart Association's Life Simple 7 (LS7) and cardiovascular disease (CVD) incidence is well documented. However, research exploring the association between CVH and specific risk factors for cardiometabolic disease is sparse in diverse cohorts.

METHODS

This study included 7717 participants from the Mediators of Atherosclerosis in South Asians Living in America and the Multi-Ethnic Study of Atherosclerosis cohorts. We assigned each LS7 component a 0, 1, and 2 and summed these scores to derive an overall CVH score. Visceral, subcutaneous, and intermuscular fat area, pericardial fat volume, and hepatic fat attenuation were measured using noncontrast computed tomography. Multivariable linear regression was used to examine associations between CVH categories and each log-transformed ectopic fat depot, as well as the homeostatic assessment for insulin resistance (HOMA-IR).

RESULTS

In adjusted analysis, compared to those with ideal CVH, participants with poor CVH demonstrated 63.4% (95% CI, 54.3-73.0) higher visceral fat area, 84.0% (95% CI, 76.5-92.1) higher pericardial fat volume, 61.6% (95% CI, 50.7-73.2) higher subcutaneous fat area, and 40.6% (95% CI, 30.2-52.0) higher intermuscular fat area, and 15.1% (95% CI, 13.1-17.2) higher hepatic fat (all Ps < 0.001). Also, poor CVH was associated with 148.2% (95% CI, 131.1-166.7) higher HOMA-IR. We also found significant heterogeneity in the strengths of association by race/ethnicity for each ectopic fat depot.

CONCLUSION

Poor and intermediate CVH, as defined by LS7 metrics, were associated with significantly higher measures of ectopic fat and insulin resistance among individuals from 5 racial/ethnic groups.

Hepatic Fat in Participants With and Without Incident Diabetes in the Diabetes Prevention Program Outcome Study

CONTEXT

There is little information about fatty liver in prediabetes as it transitions to early diabetes.

OBJECTIVE

This study is aimed at evaluating the prevalence and determinants of fatty liver in the Diabetes Prevention Program (DPP).

METHODS

We measured liver fat as liver attenuation (LA) in Hounsfield units (HU) in 1876 participants at ~14 years following randomization into the DPP, which tested the effects of lifestyle or metformin interventions versus standard care to prevent diabetes. LA was compared among intervention groups and in those with versus without diabetes, and associations with baseline and follow-up measurements of anthropometric and metabolic covariates were assessed.

RESULTS

There were no differences in liver fat between treatment groups at 14 years of follow-up. Participants with diabetes had lower LA (mean ± SD: 46 ± 16 vs 51 ± 14 HU; P < 0.001) and a greater prevalence of fatty liver (LA < 40 HU) (34% vs 17%; P < 0.001). Severity of metabolic abnormalities at the time of LA evaluation was associated with lower LA categories in a graded manner and more strongly in those with diabetes. Averaged annual fasting insulin (an index of insulin resistance [OR, 95% CI 1.76, 1.41-2.20]) waist circumference (1.63, 1.17-2.26), and triglyceride (1.42, 1.13-1.78), but not glucose, were independently associated with LA < 40 HU prevalence.

CONCLUSION

Fatty liver is common in the early phases of diabetes development. The association of LA with insulin resistance, waist circumference, and triglyceride levels emphasizes the importance of these markers for hepatic steatosis in this population and that assessment of hepatic fat in early diabetes development is warranted.

Incremental prognostic value of non-alcoholic fatty liver disease over coronary computed tomography angiography findings in patients with suspected coronary artery disease

AIMS

This study aimed to investigate additional risk stratification benefits of hepatic steatosis (HS) concurrently assessed during coronary computed tomography angiography (CTA) in a large patient cohort with suspected stable coronary artery disease (CAD).

METHODS AND RESULTS

In this prospective study, 1148 Japanese outpatients without a history of CAD who underwent coronary CTA for suspected stable CAD (mean age 64 ± 14 years) were included. HS, defined on CT as a hepatic-to-spleen attenuation ratio of <1.0, was examined just before the evaluation of adverse CTA findings, defined as obstructive and/or high-risk plaque. The major adverse cardiac events (MACE) were the composite of cardiac death, acute coronary syndrome, and late revascularization. The incremental predictive value of HS was evaluated using the global χ2 test and C-statistic. HS was identified in 247 (22%) patients. During a median follow-up of 3.9 years, MACE was observed in 40 (3.5%) patients. HS was significantly associated with MACE in a model that included adverse CTA findings (hazard ratio 4.01, 95% confidence interval 2.12-7.59, P < 0.001). By adding HS to the Framingham risk score and adverse CTA findings, the global χ2 score and C-statistic significantly increased from 29.0 to 49.5 (P < 0.001) and 0.74 to 0.81 (P = 0.026), respectively. In subgroup analyses in patients with diabetes mellitus and metabolic syndrome, HS had significant additive predictive value for MACE over the Framingham risk score and adverse CTA findings.

CONCLUSION

In patients with suspected stable CAD, concurrent evaluation of HS during coronary CTA enables more accurate detection of patients at higher risk of MACE.

Multi-Ethnic Study of Atherosclerosis (MESA): JACC Focus Seminar 5/8

The MESA (Multi-Ethnic Study of Atherosclerosis) is a National Heart, Lung, and Blood Institute-sponsored prospective study aimed at studying the prevalence, progression, determinants, and prognostic significance of subclinical cardiovascular disease in a sex-balanced, multiethnic, community-dwelling U.S. cohort. MESA helped usher in an era of noninvasive evaluation of subclinical atherosclerosis presence, burden, and progression for the evaluation of atherosclerotic cardiovascular disease risk, beyond what could be predicted by traditional risk factors alone. Concepts developed in MESA have informed international patient care guidelines, providing new tools to effectively guide public health policy, population screening, and clinical decision-making. MESA is grounded in an open science model that continues to be a beacon for collaborative science. In this review, we detail the original goals of MESA, and describe how the scope of MESA has evolved over time. We highlight 10 significant MESA contributions to cardiovascular medicine, and chart the path forward for MESA in the year 2021 and beyond.

Correlation Between Anthropometric Measurements and Non-alcoholic Fatty Liver Disease in Individuals With Obesity Undergoing Bariatric Surgery: Cross-Sectional Study

BACKGROUND

We hypothesize that non-alcoholic fatty liver disease (NAFLD) may be significantly associated with waist circumference (WC), neck circumference (NC), hip circumference (HC), and waist-to-hip ratio (WHR).

OBJECTIVES

To analyze correlations between anthropometric parameters and the occurrence and intensity of NAFLD aspects assessed by histopathological examination in individuals undergoing bariatric surgery.

METHODS

This is a cross-sectional study carried out in a tertiary university hospital. Demographic, clinical, anthropometric, laboratory, and histopathological variables were analyzed; uni- and multivariate analyses were performed. Histopathological variables analyzed were findings of liver biopsies collected during surgical procedures.

RESULTS

Of 119 individuals, 105 (88.2%) were female. The mean age was 38.8 ± 9.3 years and the mean BMI was 37.6 ± 3.1 kg/m². The prevalence of NAFLD histopathological aspects was: steatosis (76.5%), steatohepatitis (49.6%), and fibrosis (51.3%). WC was significantly higher in individuals with steatosis (103.5 ± 9.9 vs. 99.4 ± 8.4; p = 0.03). Individuals with steatohepatitis presented significantly higher BMI (38.2 ± 3.2 vs. 36.7 ± 2.8; p = 0.01), WC (105.3 ± 10.4 vs. 99.6 ± 8.8; p = 0.002), and WHR (1 ± 0.1 vs. 0.9 ± 0.1; p = 0.02). Age (40.6 ± 9.7 vs. 37 ± 8.5; p = 0.03) and hemoglobin A1c (6.5 ± 0.5 vs. 5.6 ± 0.5; p = 0.004) were significantly higher among individuals with fibrosis. A positive correlation was observed between the steatosis intensity and WHR (R = 0.2; p = 0.04). BMI (R = 0.2; p = 0.02) and glucose (R = 0.2; p = 0.009) were independently correlated with the steatohepatitis intensity. Age (R = 0.3; p = 0.04) was independently correlated with the fibrosis intensity.

CONCLUSION

There were significant associations between anthropometric parameters and NAFLD aspects. WC and WHR were associated with steatosis; BMI, WC, and WHR were associated with steatohepatitis. WHR independently correlated with steatosis intensity.

Life's Simple 7 and Nonalcoholic Fatty Liver Disease: The Multiethnic Study of Atherosclerosis

BACKGROUND

The American Heart Association (AHA) has defined Life's Simple 7 (LS7) as a measure of overall cardiovascular health . Nonalcoholic fatty liver disease (NAFLD) has been involved as a risk factor for cardiovascular disease. We evaluated the association between LS7 and NAFLD.

METHODS

We evaluated participants form the Multi-Ethnic Study of Atherosclerosis (MESA) cohort. Cardiovascular health score was calculated from the Life's Simple 7 metrics. A score of 0-8 was considered inadequate, 9-10 average, and 11-14 optimal. NAFLD was defined using noncontrast cardiac computed tomography (CT) and a liver/spleen attenuation ratio (L/S) < 1. Multivariable regression were performed to evaluate the association.

RESULTS

Our cross-sectional analysis of 3901 participants showed 19% (n = 747) had optimal cardiovascular health, 33% (n = 1270) had average, and 48% (n = 1884) had inadequate. White participants were most likely to have an optimal score (51%, n = 378), whereas African American participants had the lowest proportion with optimal scores (16%, n = 120; P < 0.001). The overall prevalence of NAFLD was 18% with a distribution of 7%, 14%, and 25% in the optimal, average, and inadequate score categories, respectively (P < 0.001). Adjusted for risk factors, average and optimal health categories had lower odds of NAFLD compared to those with inadequate scores: odds ratio for average, 0.44 (95% confidence interval 0.36-0.54); optimal, odds ratio 0.19 (95% confidence interval 0.14-0.26). This association was similar across gender, race and age groups.

CONCLUSION

A more favorable cardiovascular health score was associated with a lower prevalence of NAFLD. This study may suggest a potential of Life's Simple 7 in the prevention of liver disease.

Non-alcoholic fatty liver disease (NAFLD) in non-obese individuals

Individuals with non-alcoholic fatty liver disease (NAFLD) who lack classical risk factors also have the ability to develop nonalcoholic steatohepatitis (NASH) and progression to more advanced liver disease. The pathophysiology and risk factors for the development of NAFLD in non-obese persons are not fully understood but seem to be closely related to insulin resistance, atherogenic dyslipidaemia and alterations in body composition, with some patients harbouring predisposing genetic polymorphisms. In normal-weight individuals, also called 'lean', there is limited potential for effective lifestyle change in disease management. Additionally, biological mechanisms underlying the development of NASH in non-obese individuals may reveal novel targets for intervention. In this review, the authors discuss the clinical, histological and genetic features and risk factors for non-obese NAFLD and highlight gaps in knowledge and areas for future research.

Sex- and Age-Related Differences in the Contribution of Ultrasound-Measured Visceral and Subcutaneous Abdominal Fat to Fatty Liver Index in Overweight and Obese Caucasian Adults

Differences in body fat distribution may be a reason for the sex-, age-, and ethnicity-related differences in the prevalence of fatty liver disease (FL). This study aimed to evaluate the sex- and age-related differences in the contribution of visceral (VAT) and subcutaneous (SAT) abdominal fat, measured by ultrasound, to fatty liver index (FLI) in a large sample of overweight and obese Caucasian adults, and to identify the VAT and SAT cut-off values predictive of high FL risk. A cross-sectional study on 8103 subjects was conducted. Anthropometrical measurements were taken and biochemical parameters measured. VAT and SAT were measured by ultrasonography. FLI was higher in men and increased with increasing age, VAT, and SAT. The sex*VAT, age*VAT, sex*SAT, and age*SAT interactions negatively contributed to FLI, indicating a lower VAT and SAT contribution to FLI in men and in the elderly for every 1 cm of increment. Because of this, sex- and age-specific cut-off values for VAT and SAT were estimated. In conclusion, abdominal adipose tissue depots are associated with FLI, but their contribution is sex- and age-dependent. Sex- and age-specific cut-off values of ultrasound-measured VAT and SAT are suggested, but they need to be validated in external populations.

Nonalcoholic Fatty Liver Disease Is Associated With Arterial Distensibility and Carotid Intima-Media Thickness: (from the Multi-Ethnic Study of Atherosclerosis)

Nonalcoholic fatty liver disease (NAFLD) is considered a potential independent risk factor for cardiovascular disease (CVD). The Multi-Ethnic Study of Atherosclerosis cohort enrolled 6,814 adults without previous CVD. We excluded 2,692 participants who had missing variables, were heavy drinkers, or history of steroid use and/or chronic liver disease. NAFLD was defined using noncontrast cardiac CT and a liver/spleen Hounsfield Unit attenuation ratio <1. Ultrasound-measured carotid arterial compliance and stiffness, was expressed as distensibility coefficient and Young's modulus. Common and internal carotid intima-media thickness (CIMT) and coronary artery calcium (CAC) >0 were used as markers of subclinical CVD. A multivariate robust linear regression and logistic regression analysis were done to evaluate the association of NAFLD and this subclinical CVD markers. Our analysis of 4,123 participants showed 55% were female with a mean age of 63 (±10) years, 39% white, 10% Chinese, 28% black, and 23% were Hispanic. The prevalence of NAFLD was 17% (n = 729). Patients with NAFLD had higher distensibility coefficient and higher CIMT. Multivariate linear regression analysis showed the presence of NAFLD was associated with both the common carotid and internal carotid IMT and logCAC. Logistic analysis showed an independent association with CAC > 0 (odds ratio [OR] 1.44 95% confidence interval [CI] 1.18, 1.75) and CIMT > 1 mm (OR 1.30 95% 1.08, 1.56). When stratified by race the association with CIMT > 1 mm was significant in whites (OR 1.37 95% 1.00, 1.90) and Hispanic (OR 1.53 95% 1.08, 2. 17) and CAC > 0 was significant in Hispanics (OR 1.52 95% 1.06, 2.19). In conclusion, NAFLD is modestly associated with carotid IMT and coronary artery calcification in a multiethnic population.

Body Composition and Diabetes Risk in South Asians: Findings From the MASALA and MESA Studies

OBJECTIVE

South Asians have a higher prevalence of type 2 diabetes compared with other race/ethnic groups. Body composition is associated with the risk for type 2 diabetes. Differences in body composition between South Asians and other race/ethnic groups are one hypothesized mechanism to explain the disproportionate prevalence of type 2 diabetes in this population.

RESEARCH DESIGN AND METHODS

This study used data from the Mediators of Atherosclerosis in South Asians Living in America (MASALA) and the Multi-Ethnic Study of Atherosclerosis (MESA) cohorts to determine whether body composition mediated the elevated prevalence of impaired fasting glucose and type 2 diabetes in South Asians. Participants (n = 2,615) with complete body composition data were included. Ordinal logistic regression models were calculated to determine the odds for glycemic impairment in South Asians compared with the MESA cohort.

RESULTS

In multivariate models, South Asians had a significantly higher prevalence of glycemic impairment and type 2 diabetes compared with all four race/ethnic groups included in the MESA (P < 0.001 for all). In unadjusted and multivariate adjusted models, South Asians had higher odds for impaired fasting glucose and type 2 diabetes compared with all other race/ethnic groups (P < 0.001 for all). The addition of body composition measures did not significantly mitigate this relationship.

CONCLUSIONS

We did not identify strong evidence that accounting for body composition explains differences in the risk for type 2 diabetes. Future prospective studies of the MESA and MASALA cohorts are needed to understand how adipose tissue impacts the risk for type 2 diabetes and how to best assess this risk.

High prevalence of non-alcoholic fatty liver disease and metabolic risk factors in Guatemala: A population-based study

BACKGROUND

There are no data on the prevalence of non-alcoholic fatty liver disease (NAFLD) in general population samples in Guatemala or in other Central American countries. The prevalence and distribution of NAFLD and its associated risk factors were evaluated in a population-based sample of adults in Guatemala.

METHODS

Cross-sectional study of 411 men and women 40 years of age or older residing in urban and rural areas of Guatemala. Metabolic outcomes included obesity, central obesity, hypercholesterolemia, diabetes, and metabolic syndrome (MetS). Liver disease outcomes included elevated liver enzymes, elevated Fatty Liver Index (FLI), and elevated FIB-4 score.

RESULTS

The overall prevalence of obesity, central obesity, diabetes, and MetS were 30.9, 74.3, 21.6, and 64.2%, respectively. The fully-adjusted prevalence ratios (95% CI) for obesity, central obesity, diabetes, and MetS comparing women to men were 2.83 (1.86-4.30), 1.72 (1.46-2.02), 1.18 (1.03-1.34), and 1.87 (1.53-2.29), respectively. The overall prevalence of elevated liver enzymes (ALT or AST), elevated FLI, and elevated FIB-4 scores were 38.4, 60.1, and 4.1%, respectively. The fully-adjusted prevalence ratios (95% CI) for elevated liver enzymes (either ALT or AST) and elevated FLI score comparing women to men were 2.99 (1.84-4.86) and 1.47 (1.18-1.84), respectively.

CONCLUSIONS

The prevalence of metabolic abnormalities and liver outcomes in this general population study was very high. The prevalence of metabolic and liver abnormalities was particularly high among women, an observation that could explain the atypical 1:1 male to female ratio of liver cancer in Guatemala.

Circulating Interleukin-6 is a biomarker for coronary atherosclerosis in nonalcoholic fatty liver disease: Results from the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Biomarkers to predict the presence and severity of subclinical cardiovascular disease (CVD) in nonalcoholic fatty liver disease (NAFLD) are lacking.

METHODS

3876 participants from the Multi-Ethnic Study of Atherosclerosis (MESA), without known chronic liver disease underwent baseline non-contrast cardiac CT, with NAFLD defined by validated liver:spleen ratio (L:S) < 1.0, and subclinical CVD defined by coronary artery calcium (CAC) score > 0. Randomly-selected subgroups underwent detailed inflammatory marker testing, including LpPLA2 mass (N = 2951), activity (N = 3020), high-sensitivity C-reactive protein (hsCRP; N = 3849), and interleukin-6 (IL-6; N = 3764). Among those with NAFLD, we estimated the prevalence of CAC > 0 and CAC > 100 for each SD biomarker increase, using multivariable log-binomial regression models adjusted for cardiometabolic risk factors.

RESULTS

Seventeen percent (N = 668) of participants met the criteria for NAFLD. NAFLD participants were younger (mean age 61 ± 10 vs. 63 ± 10 years, p < .0001) but more likely to have an elevated BMI (mean 31.1 ± 5.5 vs. 28.0 ± 5.2 kg/m2, p < .0001), diabetes (22% vs. 11%, p < .0001), and increased inflammatory biomarkers, including LpPLA2 activity, hsCRP and IL-6 (all p < .0001). Among NAFLD participants, IL-6 was the only biomarker independently associated with prevalent CAC > 0 (PR = 1.06 [1.00-1.11]), or CAC > 100 (PR = 1.09 [1.02-1.17]). In contrast, circulating LpPLA2 mass/activity and hsCRP were not associated with either the prevalence or severity of subclinical CVD (all p > .05).

CONCLUSION

In a large, multi-ethnic population with NAFLD, IL-6 is independently associated with the prevalence and severity of subclinical atherosclerosis. Further research into the longitudinal effects of NAFLD on progressive CVD will determine whether IL-6 is a marker or mediator of NAFLD-related atherosclerosis.

Pericardial, But Not Hepatic, Fat by CT Is Associated With CV Outcomes and Structure: The Multi-Ethnic Study of Atherosclerosis

OBJECTIVES

The study sought to determine the associations between local (pericardial) fat and incident cardiovascular disease (CVD) events and cardiac remodeling independent of markers of overall adiposity.

BACKGROUND

The impact of pericardial fat-a local fat depot encasing the heart-on myocardial function and long-term CV prognosis independent of systemic consequences of adiposity or hepatic fat is an area of active debate.

METHODS

We studied 4,234 participants enrolled in the MESA (Multi-Ethnic Study of Atherosclerosis) study with concomitant cardiac magnetic resonance imaging and computed tomography (CT) measurements for pericardial fat volume and hepatic attenuation (a measure of liver fat). Poisson and Cox regression were used to estimate the annualized risk of incident hard atherosclerotic CVD (ASCVD), all-cause death, heart failure, all-cause CVD, hard coronary heart disease, and stroke as a function of pericardial and hepatic fat. Generalized additive models were used to assess the association between cardiac magnetic resonance indices of left ventricular (LV) structure and function and pericardial fat. Models were adjusted for relevant clinical, demographic, and cardiometabolic covariates.

RESULTS

MESA study participants with higher pericardial and hepatic fat were more likely to be older, were more frequently men, and had a higher prevalence of cardiometabolic risk factors (including dysglycemia, dyslipidemia, hypertension), as well as adiposity-associated inflammation. Over a median 12.2-year follow-up (interquartile range: 11.6 to 12.8 years), pericardial fat was associated with a higher rate of incident hard ASCVD (standardized hazard ratio: 1.22; 95% confidence interval: 1.10 to 1.35; p = 0.0001). Hepatic fat by CT was not significantly associated with hard ASCVD (standardized hazard ratio: 0.96; 95% confidence interval: 0.86 to 1.08; p = 0.52). Higher pericardial fat was associated with greater indexed LV mass (37.8 g/m2.7 vs. 33.9 g/m2.7, highest quartile vs. lowest quartile; p < 0.01), LV mass-to-volume ratio (1.2 vs. 1.1, highest quartile vs. lowest quartile; p < 0.01). In adjusted models, a higher pericardial fat volume was associated with greater LV mass (p < 0.0001) and concentricity (p < 0.0001).

CONCLUSIONS

Pericardial fat is associated with poorer CVD prognosis and LV remodeling, independent of insulin resistance, inflammation, and CT measures of hepatic fat.

Hepatic steatosis in participants in a program of low-dose CT screening for lung cancer

OBJECTIVE

Determine the frequency of moderate-to-severe hepatic steatosis (HS) in asymptomatic participants in a low-dose CT (LDCT) screening program for lung cancer, to identify risk factors, and develop recommendations.

METHODS

Baseline LDCT scans of the chest of 170 participants in an IRB-approved study between August 2011 and April 2016 were reviewed. Demographic variables, comorbidities, and liver function tests were documented. Hepatic and splenic attenuation values hounsfield unit (HU) were measured. Regression analyses were performed.

RESULTS

Average liver attenuation was 57.6HU (standard deviation (SD) 9.3) and average liver/spleen (L/S) ratio was 1.3 (SD 0.3). Liver attenuation was <40HU for 9 (5.3%), liver/spleen (L/S) ratio <0.8 for 6 (3.5%), and either <40HU or L/S ratio <0.8 for 9 (5.3%). Male sex (p=0.004), diabetes (p=0.0005), emphysema (p=0.03), and high BMI (p=0.0006) were significant predictors of HS. Aspartate aminotransferase (p=0.0018) and alanine aminotransferase (p=0.012) were negatively correlated with liver attenuation. Reduced serum levels of alpha-1-antitrypsin may be a common factor of emphysema and HS.

CONCLUSION

LDCT can detect HS in asymptomatic participants with frequencies similar to previous reports. If liver attenuation is below 40HU and/or L/S ratio below 0.8, further evaluation of HS to the primary care physician or liver specialist is recommended.

Interethnic Differences in Serum Lipids and Implications for Cardiometabolic Disease Risk in African Ancestry Populations

African Americans generally have a healthier lipid profile (lower triglycerides and higher high-density lipoprotein cholesterol concentration) compared with those of other ethnicities. Paradoxically, African Americans do not experience a decreased risk of the cardiometabolic diseases that serum lipids are expected to predict. This review explores this mismatch between biomarker and disease among African ancestry individuals by investigating the presence of interethnic differences in the biological relationships underlying the serum lipids-disease association. This review also discusses the physiologic and genomic factors underlying these interethnic differences. Additionally, because of the importance of serum lipids in assessing disease risk, interethnic differences in serum lipids have implications for identifying African ancestry individuals at risk of cardiometabolic disease. Where possible, data from Africa is included, to further elucidate these ancestral differences in the context of a different environmental background.

Cardiometabolic Abnormalities Among Normal-Weight Persons From Five Racial/Ethnic Groups in the United States: A Cross-sectional Analysis of Two Cohort Studies

BACKGROUND

The relationship between body weight and cardiometabolic disease may vary substantially by race/ethnicity.

OBJECTIVE

To determine the prevalence and correlates of the phenotype of metabolic abnormality but normal weight (MAN) for 5 racial/ethnic groups.

DESIGN

Cross-sectional analysis.

SETTING

2 community-based cohorts.

PARTICIPANTS

2622 white, 803 Chinese American, 1893 African American, and 1496 Hispanic persons from MESA (Multi-Ethnic Study of Atherosclerosis) and 803 South Asian participants in the MASALA (Mediators of Atherosclerosis in South Asians Living in America) study.

MEASUREMENTS

Prevalence of 2 or more cardiometabolic abnormalities (high fasting glucose, low high-density lipoprotein cholesterol, and high triglyceride levels and hypertension) among normal-weight participants was estimated. Correlates of MAN were assessed by using log-binomial models.

RESULTS

Among normal-weight participants (n = 846 whites, 323 Chinese Americans, 334 African Americans, 252 Hispanics, and 195 South Asians), the prevalence of MAN was 21.0% (95% CI, 18.4% to 23.9%) in whites, 32.2% (CI, 27.3% to 37.4%) in Chinese Americans, 31.1% (CI, 26.3% to 36.3%) in African Americans, 38.5% (CI, 32.6% to 44.6%) in Hispanics, and 43.6% (CI, 36.8% to 50.6%) in South Asians. Adjustment for demographic, behavioral, and ectopic body fat measures did not explain racial/ethnic differences. After adjustment for age, sex, and race/ethnicity-body mass index (BMI) interaction, for the equivalent MAN prevalence at a BMI of 25.0 kg/m2 in whites, the corresponding BMI values were 22.9 kg/m2 (CI, 19.5 to 26.3 kg/m2) in African Americans, 21.5 kg/m2 (CI, 18.5 to 24.5 kg/m2) in Hispanics, 20.9 kg/m2 (CI, 19.7 to 22.1 kg/m2) in Chinese Americans, and 19.6 kg/m2 (CI, 17.2 to 22.0 kg/m2) in South Asians.

LIMITATION

Cross-sectional study design and lack of harmonized dietary data between studies.

CONCLUSION

Compared with whites, all racial/ethnic minority groups had a statistically significantly higher prevalence of MAN, which was not explained by demographic, behavioral, or ectopic fat measures. Using a BMI criterion for overweight to screen for cardiometabolic risk may result in a large proportion of racial/ethnic minority groups being overlooked.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Obesity, Hepatic Steatosis, and Their Impact on Fat Infiltration of the Trunk Musculature Using Unenhanced Computed Tomography

OBJECTIVES

The aim of the study was to assess whether hepatic steatosis predicts muscle fat content independent of body mass index (BMI).

METHODS

Regions of interest were drawn over several trunk muscles and over the right lobe of the liver to obtain the computed tomography (CT) density in 100 subjects with unenhanced CT studies of the abdomen and pelvis. Univariate and multivariate linear regression were used to examine the associations between BMI and hepatic steatosis and between BMI and trunk muscle density.

RESULTS

Body mass index was associated with trunk muscle fat (P < 0.05) and hepatic steatosis (P < 0.05). Computed tomography density of the liver correlated with that of each trunk muscle (P < 0.05). After adjusting for age, sex, and BMI, hepatic steatosis was associated with increased trunk muscle fat content in the psoas only.

CONCLUSIONS

The association between muscle fat in most trunk muscles and hepatic steatosis is due to underlying BMI. However, hepatic steatosis predicted psoas muscle fat content independent of BMI (P < 0.05).

Fatty Liver Disease, Women, and Aldosterone: Finding a Link in the Jackson Heart Study

Context:

Fatty liver disease is one of the most common forms of chronic liver disease. The renin-angiotensin-aldosterone system has been implicated in the pathogenesis of fatty liver.

Objective:

Determine the relationship between fatty liver and aldosterone in a large cohort study.

Design:

Community-based, observational cohort study of African Americans.

Setting:

The original Jackson Heart Study cohort enrolled African American participants from the Jackson, Mississippi, metropolitan area in Hinds, Madison, and Rankin Counties.

Participants:

Our study population consisted of 2507 Jackson Heart Study participants (1625 women and 882 men) who had liver attenuation measured per computed tomography scans, had aldosterone measurements, and were not taking angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or mineralocorticoid receptor antagonists.

Intervention:

There was no intervention.

Main outcome measure:

Liver attenuation on computed tomography scans.

Results:

Univariate regression analysis demonstrated a statistically significant correlation between aldosterone levels and liver attenuation. Each doubling of aldosterone was associated with 1.08 Hounsfield unit decrease (95% confidence interval, 1.47 to −0.69, P < 0.001). A multivariable model adjusted for body mass index, age, alcohol intake, and homeostatic model assessment of insulin resistance determined that the association was statistically significant only for women.

Conclusion:

Our data demonstrate a positive association between aldosterone levels and fatty liver in African American women.

Management of Nonalcoholic Fatty Liver Disease in Patients With Type 2 Diabetes: A Call to Action

Traditionally a disease of hepatologists, nonalcoholic fatty liver disease (NAFLD) has recently become a major concern for a broad spectrum of health care providers. Endocrinologists and those caring for patients with type 2 diabetes mellitus (T2DM) are at center stage, as T2DM appears to worsen the course of NAFLD and the liver disease makes diabetes management more challenging. However, the nature of this relationship remains incompletely understood. Although the increasing prevalence of NAFLD is frequently attributed to the epidemic of obesity and is often oversimplified as the "hepatic manifestation of the metabolic syndrome," it is a much more complex disease process that may also be observed in nonobese individuals and in patients without clinical manifestations of the metabolic syndrome. It carries both metabolic and liver-specific complications that make its approach unique among medical conditions. Diabetes appears to promote the development of nonalcoholic steatohepatitis (NASH), the more severe form of the disease, and increases the risk of cirrhosis and hepatocellular carcinoma. Patients and physicians face many uncertainties, including fragmented information on the natural history of the disease, challenges in the diagnosis of NASH, and few pharmacological agents with proven efficacy. However, recent advances in diagnosis and treatment, combined with the risk of serious consequences from inaction, call for health care providers to be more proactive in the management of patients with T2DM and NASH.

Race/ethnic and sex disparities in the non-alcoholic fatty liver disease-abdominal aortic calcification association: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

This study investigated the associations of non-alcoholic fatty liver disease (NAFLD) and abdominal aortic calcification (AAC) volume and density, and whether these relationships vary by race/ethnicity and/or sex, information that are limited in current literature.

METHODS

We studied 1004 adults from the Multi-Ethnic Study of Atherosclerosis to assess the relationship between NAFLD (liver-to-spleen ratio <1) and the following measures of AAC: presence (volume score >0, using Poisson regression); change in volume score (increasing vs. no change, using Poisson regression); and morphology (volume and density score, where volume score >0, using linear regression); and interaction by race/ethnicity and sex.

RESULTS

Among Blacks, those with NAFLD had greater prevalence for AAC compared to Whites regardless of sex (Prevalence Ratio [PR] = 1.41, CI = 1.15-1.74, p-interaction = 0.02). Concurrent interaction by race/ethnicity and sex was found comparing Chinese and Blacks to Whites (p-interaction = 0.017 and 0.042, respectively) in the association between NAFLD and the prevalence of increasing AAC. Among women, this relationship was inverse among Chinese (PR = 0.59, CI = 0.28-1.27), and positive among Whites (PR = 1.34, CI = 1.02-1.76). This finding was reversed evaluating the men counterpart. Black men also had a positive association (PR = 1.86, CI = 1.29-2.70), which differed from the inverse relationship among White men, and was greater compared to Black women (PR = 1.45, CI = 1.09-1.94). NAFLD was unrelated to AAC morphology.

CONCLUSIONS

NAFLD was related to the presence of AAC, however, limited to Blacks. Significant concurrent interaction by race/ethnicity (Chinese and Blacks vs. Whites) and sex was found in the relationship between NAFLD and increasing AAC. These findings suggest disparities in the pathophysiologic pathways in which atherosclerosis develops.

Ectopic Fat Depots and Coronary Artery Calcium in South Asians Compared With Other Racial/Ethnic Groups

Background

South Asians have a low body mass index and high prevalence of cardiovascular disease (CVD) relative to other racial/ethnic groups. Radiographically detected ectopic fat distribution is better associated with CVD than body mass index. We assessed whether differences in ectopic fat depots explained differences in the prevalence/severity of coronary artery calcium (CAC), a predictor of incident CVD events, among South Asians compared with other racial/ethnic groups.

Methods and Results

We examined the associations of radiographically detected visceral, intermuscular, intrahepatic, and pericardial fat with CAC among adults without baseline CVD. We compared 803 South Asians in the Mediators of Atherosclerosis in South Asians Living in America to 4 racial/ethnic groups in the Multi‐Ethnic Study of Atherosclerosis: 2622 whites, 1893 blacks, 1496 Latinos, and 803 Chinese Americans. We adjusted for body mass index and known CVD risk factors. South Asians had the highest intrahepatic fat and lowest pericardial fat volume (PFV). There was a positive graded association between ectopic fat and higher CAC scores in all the groups with the strongest associations observed with PFV. PFV was independently associated with CAC severity in South Asians (P=0.01) and blacks (P=0.05) and borderline in whites (P=0.06). PFV partially explained the higher CAC burden in South Asians compared with blacks, but not the other racial/ethnic groups.

Conclusions

Differences in PFV explain a small fraction of the higher CAC burden in South Asians. Our findings suggest that ectopic fat depots may not explain the elevated CAC risk in South Asians.

Less favorable body composition and adipokines in South Asians compared with other US ethnic groups: results from the MASALA and MESA studies

Background

Small studies have shown that South Asians (SAs) have more total body, subcutaneous, visceral and hepatic fat and abnormal adipokine levels compared to Whites. However, comprehensive studies of body composition and adipokines in SAs compared to other ethnic groups are lacking.

Methods

Using harmonized data, we performed a cross-sectional analysis of two community-based cohorts: Mediators of Atherosclerosis of South Asians Living in America (MASALA, n=906) and Multi-Ethnic Study of Atherosclerosis (MESA which included 2,622 Whites; 803 Chinese Americans; 1,893 African Americans; and 1,496 Latinos). General linear models were developed to assess ethnic differences in ectopic fat (visceral, intermuscular, and pericardial fat; and hepatic attenuation), lean muscle mass, and adipokines (adiponectin and resistin). Models were adjusted for age, sex, site, alcohol use, smoking, exercise, education, household income and BMI. Ectopic fat models were additionally adjusted for hypertension, diabetes, HDL, and triglycerides. Adipokine models were adjusted for subcutaneous, visceral, intermuscular, and pericardial fat; and hepatic attenuation.

Results

Compared to all ethnic groups in MESA (Whites, Chinese Americans, African Americans, and Latinos), SAs had greater intermuscular fat (pairwise comparisons to each MESA group, p < 0.01), lower hepatic attenuation (p < 0.001), and less lean mass (p < 0.001). SAs had greater visceral fat compared to Chinese Americans, African Americans and Latinos (p < 0.05) and greater pericardial fat compared to African Americans (p < 0.001). SAs had lower adiponectin levels compared to other ethnic groups (p < 0.01; except Chinese Americans) and higher resistin levels than all groups (p < 0.001), even after adjusting for differences in body composition.

Conclusion

There are significant ethnic differences in ectopic fat, lean mass, and adipokines. A less favorable body composition and adipokine profile in South Asians may partially explain the increased predisposition to cardiometabolic disease. The mechanisms that underlie these differences warrant further investigation.

Epidemiological modifiers of non-alcoholic fatty liver disease: Focus on high-risk groups

An improved understanding of non-alcoholic fatty liver disease epidemiology would lead to identification of individuals at high risk of developing chronic liver disease and extra-hepatic complications, thus contributing to more effective case finding of non-alcoholic fatty liver disease among selected groups. We aimed to illustrate the epidemiology of non-alcoholic fatty liver disease in high-risk groups, which were identified based on existing literature. To this end, PubMed was searched to retrieve original articles published until May 2015 using relevant and pertinent keywords "nonalcoholic fatty liver disease" and "diabetes", "obesity", "hyperlipidaemia", "familial heterozygous hypobetalipoproteinaemia", "hypertension", "metabolic syndrome", "ethnicity", "family history" or "genetic polymorphisms". We found that age, sex and ethnicity are major physiological modifiers of the risk of non-alcoholic fatty liver disease, along with belonging to "non-alcoholic fatty liver disease families" and carrying risk alleles for selected genetic polymorphisms. Metabolic syndrome, diabetes, obesity, mixed hyperlipidaemia and hypocholesterolaemia due to familial hypobetalipoproteinaemia are the major metabolic modifiers of non-alcoholic fatty liver disease risk. Compared with these metabolic conditions, however, arterial hypertension appears to carry a relatively more modest risk of non-alcoholic fatty liver disease. A better understanding of the epidemiology of non-alcoholic fatty liver disease may result in a more liberal policy of case finding among high-risk groups.

Epidemiology of NAFLD and Type 2 Diabetes: Health Disparities Among Persons of Hispanic Origin

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver condition in the USA and worldwide and affects Hispanics disproportionally. In this review, we aim to document and contrast the epidemiology of NAFLD and type 2 diabetes, provide a framework to study health disparities in NAFLD in Hispanic populations, and identify points of action within the health care system to tackle these health disparities. NAFLD shares many common risk factors with type 2 diabetes, specially obesity and insulin resistance, but shows different prevalence patterns by ethnicity: while Hispanics are disproportionately affected by both NAFLD and type 2 diabetes, non-Hispanic black populations have a low prevalence of NAFLD. The current literature suggests a strong role of polymorphisms in the PNPLA3 gene and potential interactions with environmental factors in the pathogenesis of NAFLD. However, given potential interactions and the shared risk factors with type 2 diabetes, a health disparity approach that acknowledges upstream determinants is needed. Solutions to these determinants can also be found in the health system. The role of interventions that have shown efficacy in type 2 diabetes, like community health workers, may be implemented to prevent and control NAFLD.

The association of nonalcoholic fatty liver disease, obesity, and metabolic syndrome, with systemic inflammation and subclinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis (MESA)

INTRODUCTION

We characterized the association of 3 metabolic conditions - obesity, metabolic syndrome, and nonalcoholic fatty liver disease (NAFLD) - with increased inflammation and subclinical atherosclerosis.

METHODS

We conducted cross-sectional analysis of 3976 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with adequate CT imaging to diagnose NAFLD. Obesity was defined as BMI ≥ 30 kg/m(2), metabolic syndrome by AHA/NHLBI criteria, and NAFLD using non-contrast cardiac CT and a liver/spleen attenuation ratio (L/S) < 1. Increased inflammation was defined as high sensitivity C-reactive protein (hsCRP) ≥2 mg/L and subclinical atherosclerosis as coronary artery calcium (CAC) > 0. We studied the association of a stepwise increase in number of these metabolic conditions (0-3) with increased inflammation and CAC, stratifying results by gender and ethnicity.

RESULTS

Mean age of participants was 63 (±10) years, 45% were male, 37% white, 10% Chinese, 30% African American, and 23% were Hispanic. Adjusting for obesity, metabolic syndrome and traditional risk factors, NAFLD was associated with a prevalence odds ratio for hsCRP ≥2 mg/L and CAC >0 of 1.47 (1.20-1.79) and 1.37 (1.11-1.68) respectively. There was a positive interaction between female gender and NAFLD in the association with hsCRP ≥2 mg/L (p = 0.006), with no interaction by race. With increasing number of metabolic conditions, there was a graded increase in prevalence odds ratios of hsCRP ≥2 mg/L and CAC >0.

CONCLUSION

NAFLD is associated with increased inflammation and CAC independent of traditional risk factors, obesity and metabolic syndrome. There is a graded association between obesity, metabolic syndrome, and NAFLD with inflammation and CAC.