Relationship between drinking frequency and fatty liver prevalence or incidence in Japanese undergoing health checkup in 2008‐2019

BACKGROUND & AIMS: The relationship between the frequency of drinking and fatty liver in the general population is still poorly understood. This study analysed data from a large cohort who underwent health checkups in Japan between 2008 and 2019 to investigate the prevalence and incidence of fatty liver by alcohol consumption and risk factors for fatty liver. METHODS: The prevalence of fatty liver diagnosed with ultrasonography was calculated in 75,670 residents. The incidence of fatty liver in 31,062 residents who underwent ultrasonography at least twice during the period without fatty liver at the first time was calculated using the person‐year method. Multivariate logistic analysis was performed to investigate risk factors associated with the prevalence and incidence of fatty liver. RESULTS: The prevalence of fatty liver was 27.6% (95% confidence interval [CI], 27.2‐27.9) in non‐drinkers, 28.5% (27.5‐29.5) in moderate‐drinkers and 28.0% (26.0‐29.9) in heavy‐drinkers. The incidence of fatty liver was 3,084/100,000 person‐years (2,997‐3,172/100,000) in non‐drinkers, 3,754/100,000 person‐years (3,481‐4,042/100,000) in moderate‐drinkers and 3,861/100,000 person‐years (3,295‐4,497/100,000) in heavy‐drinkers. The prevalence and incidence of fatty liver were not associated with drinking status. Obesity was the most important independent risk factor (prevalence: adjusted odds ratio [AOR], 6.3; 95% CI, 6.0‐6.5; incidence: AOR, 2.4; 95% CI, 2.3‐2.6). CONCLUSIONS: Drinking status does not affect the prevalence or incidence of fatty liver in Japanese residents undergoing health checkups. From a public health perspective, measures for obesity control must be prioritised to reduce the burden of disease of fatty liver in Japan.