Background and aims: Liver attenuation (LA) [Hounsfield Units (HU)] by computed tomography is a validated quantitative measure that is inversely related to liver fat burden. We examined race and sex differences on the distribution of LA [one of the first stages of fatty liver disease (FLD)] and the predictors of these mean differences in European American (EA) and African American (AA) participants of the Family Heart Study.
Materials and methods: A total of 1242 (1064 EA, 178 AA) and 1477 (1150 EA, 327 AA) men and women, respectively, underwent computed tomography examination from which LA and abdominal adipose volume were measured. LA (adjusted for phantom and field center) was the dependent variable in linear mixed models (to control for family relatedness) that tested for mean differences by race and by sex. Independent explanatory variables included age, BMI, visceral adipose tissue volume (VAT), subcutaneous adipose tissue volume, alcohol consumption, triglyceride, HDL-cholesterol, and insulin resistance.
Results: Mean LA varied significantly by sex, [(men) 57.76±10.03 HU and (women) 60.03±10.91 HU, P=0.0002], but not by race. Higher LA was associated with older age, whereas higher values of VAT, triglycerides, and insulin resistance were associated with lower LA in men and women. In contrast, alcohol consumption and BMI were associated with lower LA only among men. In analyses stratified by race, LA was associated with alcohol consumption, VAT, and insulin resistance in both EA and AA and with age, BMI, and HDL-cholesterol in EA participants only.
Conclusions: Our study findings confirm that there are important sex differences and race by sex interaction effects on the distribution of LA, the prevalence of FLD, and on the influence of metabolic risk factors on LA and FLD.