Racial differences in nonalcoholic fatty liver disease in the U.S. population

Abstract

Objective: To characterize the prevalence of nonalcoholic fatty liver disease (NAFLD) by race in a nationally representative sample of the U.S. population and to investigate potential explanatory factors for racial disparities.

Design and methods: Cross-sectional study of 4,037 non-Hispanic white, 2,746 non-Hispanic black, and 2,892 Mexican-American adults in the Third National Health and Nutrition Examination Survey. NAFLD was defined using ultrasound and with elevated aminotransferases.

Results: Age-adjusted prevalence of NAFLD was highest in Mexican-Americans (21.2%), followed by non-Hispanic whites (12.5%), and was lowest in non-Hispanic blacks (11.6%). Even after adjustment for demographic, lifestyle, adiposity, and metabolic factors, compared to non-Hispanic whites, Mexican-Americans were more likely to have NAFLD (OR: 1.67, 95% CI: 1.26, 2.22). Non-Hispanic blacks were significantly less likely to have NAFLD with elevated aminotransferases (OR: 0.51, 95% CI: 0.27, 0.97). Racial differences were attenuated among those with normal BMI and among "never drinkers."

Conclusion: In this representative sample of the U.S. population, we found significant racial differences in the prevalence of ultrasound-defined NAFLD (with and without elevated liver enzymes). The racial differences were not fully explained by lifestyle, adiposity, and metabolic factors. More works is needed to identify potential contributors.

Appendix Figure 1

Age-adjusted prevalence (95% confidence interval) for NAFLD* by race and body mass index group among participants without diabetes (Panel A) and among participants with diabetes (Panel B). *NAFLD was defined as the presence of moderate or severe hepatic steatosis by ultrasound in the absence of alcohol consumption >1 drink/day for women and >2 drinks/day for men and in the absence of the current use of zydovudine or didanosine, medications shown to induce hepatic steatosis. † p<0.05 comparing Mexican-Americans to non-Hispanic whites ‡ p<0.05 comparing non-Hispanic blacks to non-Hispanic whites

Appendix Figure 2

Age-adjusted prevalence (95% confidence interval) for NAFLD* by race and body mass index group among physically active participants (Panel A) and among physically inactive participants (Panel B). *NAFLD was defined as the presence of moderate or severe hepatic steatosis by ultrasound in the absence of alcohol consumption >1 drink/day for women and >2 drinks/day for men and in the absence of the current use of zydovudine or didanosine, medications shown to induce hepatic steatosis. † p<0.05 comparing Mexican-Americans to non-Hispanic whites ‡ p<0.05 comparing non-Hispanic blacks to non-Hispanic whites

Figure

Age-adjusted prevalence (95% confidence interval) for NAFLD* (Panels A [men] and B [women]) and NAFLD with elevated aminotransferases** (Panels C [men] and D [women]) by race and body mass index group. *NAFLD was defined as the presence of moderate or severe hepatic steatosis by ultrasound in the absence of alcohol consumption >1 drink/day for women and >2 drinks/day for men and in the absence of the current use of zydovudine or didanosine, medications shown to induce hepatic steatosis. **NAFLD with elevated aminotransferases was defined as the presence of NAFLD and elevated ALT or AST, defined as above the upper limit of normal of the NHANES laboratory values (ALT: >40 U/L for men and >31 U/L for women; AST: >37 U/L for men and >31 U/L for women), in the absence of hepatitis B, hepatitis C, and transferrin saturation >50%. † p<0.05 comparing Mexican-Americans to non-Hispanic whites ‡ p<0.05 comparing non-Hispanic blacks to non-Hispanic whites