Unrecognised rural-urban disparities in epidemiology of metabolic-associated fatty liver disease in the representative area of China

Abstract

Background: The unexpectedly increased burden of metabolic-associated fatty liver disease (MAFLD) continues in China, and the differences between rural and urban areas remain unclear. We aimed to clarify the prevalence and risk factors in rural areas of China.

Methods: This cross-sectional study used the most densely populated area with highly unbalanced development differences in China (Guangdong Province) as a representative sample, and multistage stratified random sampling was performed. The participants' demographic, socioeconomic and lifestyle data were collected. Fatty liver and liver stiffness were screened by FibroScan.

Results: A total of 7287 individuals were enrolled (rural: 2684; urban: 4603). The overall MAFLD prevalence was 35.7%, and MAFLD was higher among rural individuals (38.0% vs 34.4%, p<0.001) than urban individuals. Rural individuals had more severe hepatic fibrosis (fibrosis stage 3-4) overall (3.0% vs 1.3%) and among different sexes (male: 4.2% vs 2.0%; female: 1.5% vs 0.5%) (all p<0.05) than urban individuals. For both rural and urban individuals, lifestyle and dietary habits, including midnight snacks, dining out, and overeating salt, red meat and sugar, were associated with an increased risk of MAFLD, and drinking tea and consuming dietary fibres were associated with a decreased risk of MAFLD. However, midnight snacks and overeating red meat were associated with a higher risk of hepatic fibrosis only in urban individuals.

Conclusion: There is a surprisingly high burden of MAFLD in rural Guangdong, China, which implicates a lack of awareness among rural individuals and a warrant the need for disease counteraction strategies.

Trial registration number: ChiCTR2000033376.

Keywords: Dietary patterns; Metabolic syndrome.

Figure 1. The centres participating in recruitment. (A) Geographical distribution of sample site in Guangdong Province, China. (B) A flow diagram for participants recruitment in this study. HBV, hepatitis B virus; HCV, hepatitis C virus.

Figure 2. Proportion of NAFLD, MAFLD and MAFLD subtypes prevalence of all participants (A), rural (B) and urban (C) individuals. MAFLD, metabolic-associated fatty liver disease; NAFLD, non-alcoholic fatty liver disease.

Figure 3. Comparison of distribution of degrees of hepatic steatosis (A), whether having liver injury (B) and hepatic fibrosis (C) between rural and urban individuals in different stratification including age, gender and MAFLD subtypes. CAP, controlled attenuation parameter; MAFLD, metabolic-associated fatty liver disease; T2DM, type-2 diabetes mellitus; TE, transient elastography.

Figure 4. Forest plot for performance on different lifestyle factors of the prevalence of MAFLD in both rural and urban individuals. Adjustment factors included age, gender, employment, education, income, history of hypertension and diabetes, total energy intake per day, BMI, ALT, GGT, uric acid, total cholesterol and triglyceride. OR and 95% CIs were given and visually represented by the squares and error bars. Vertical dot dash lines=1; *=p<0.05. ALT, alanine aminotransferase; BMI, body mass index; GGT, transpeptidase; MAFLD, metabolic-associated fatty liver disease.

Figure 5. Forest plot for performance on different dietary habits of the prevalence of MAFLD in both rural and urban individuals. Adjustment factors included age, gender, employment, education, income, history of hypertension and diabetes, total energy intake per day, BMI, ALT, GGT, uric acid, total cholesterol and triglyceride. OR and 95% CIs were given and visually represented by the squares and error bars. Vertical dot dash lines=1; *p<0.05. ALT, alanine aminotransferase; BMI, body mass index; GGT, transpeptidase; MAFLD, metabolic-associated fatty liver disease.