Early Screening And The Factors Associated With Development Of Nonalcoholic Fatty Liver Disease

Background As a popular and rapid increased noncommunicable disease,nonalcoholic fatty liver disease has been an important public health concern worldwide.Over the last three decades,dietary habits and lifestyles have remarkly changed with the economic development,which resulted in the increasing prevalence of noncommunicable diseases in China,including nonalcoholic fatty liver disease.Considering the public health burden brought by the increasing nonalcoholic fatty liver disease,early screening and investigations of factors associated with nonalcoholic fatty liver disease have become eventually crucial in China.In this study,we examined the accuracy and optimal cut-off point of fatty liver index for early screening of nonalcoholic fatty liver disease,and investigated the factors significantly associated with the development of nonalcoholic fatty liver disease in middle-aged and elderly Chinese,especially the lifestyle factors.Study design and methods 1.The roles of fatty liver index in early screening of nonalcoholic fatty liver disease: 10375 participants aged 40 years or above were recruited from Jiading district,Shanghai,and 8626 participants were included in this study.Questionnaire was used for collecting lifestyle and sociodemographic information.Anthropometric measurements,blood and urine sampling were performed.The hepatic ultrasonography was conducted for diagnosing nonalcoholic fatty liver disease.The fatty liver index consisted of four factors: waist circumference,body mass index,triglyceride,and ?-glutamyl transpeptidase.We evaluated the accuracy and optimal cut-off point of fatty liver index for screening nonalcoholic fatty liver disease at baseline study.With 4-year follow up,we validated the accuracy of fatty liver index in detecting nonalcoholic fatty liver disease in participants free of nonalcoholic fatty liver disease at baseline.2.The factors associated with incident nonalcoholic fatty liver disease.This was a prospective cohort study.Participants of this study were recruited from residents in Jiading District,Shanghai.3301 participants free of nonalcoholic fatty liver disease at baseline were performed follow-up assessments after a median interval of 4 years.We prospectively investigated the factors associated with incident nonalcoholic fatty liver disease during follow-up.Furthermore,we particularly investigated the effect of healthy lifestyle factors on the development of nonalcoholic fatty liver disease,including current nonsmoking,moderate alcohol intake,physically active,and normal weight.Results 1.In the middle-aged and elderly Chinese,the area under receiver operating characteristic curve of fatty liver index for nonalcoholic fatty liver disease was 0.834(95% confident interval [CI]: 0.825-0.842),larger than that of its each individual component(waist circumference,body mass index,triglyceride,gamma-glutamyl transpeptidase)and alanine aminotransferase.The optimal cut-off point of fatty liver index was 30,achieving a high sensitivity of 79.89% and a specificity of 71.51%.Among the participants screened by fatty liver index,worse metabolic characteristics were found than the ultrasonography-diagnosed nonalcoholic fatty liver disease patients.During the 4-year follow up in participants free of nonalcoholic fatty liver disease at baseline,each 10-unit increase of fatty liver index was associated with a 51% increased risk of nonalcoholic fatty liver disease(odds ratio [OR]: 1.51,95% CI: 1.43-1.59).Moreover,participants with fatty liver index ? 30 had a 2.41-fold increased risk of nonalcoholic fatty liver disease,comparing to those with fatty liver index lower than the cut-off point(OR: 3.41,95% CI: 2.81-4.15).2.In this survy,female sex,triglyceride,homeostasis model assessment for insulin resistance,systolic blood pressure,alanine aminotransferase,and ?-glutamyl transpeptidase were positively associated with the risk of incident nonalcoholic fatty liver disease,while older age,high-density lipoprotein cholesterol,aspartate aminotransferase were associated with a lower risk of incident nonalcoholic fatty liver disease.In addition,we found that current nonsmoking(OR: 0.60,95% CI: 0.44-0.83),physically active(OR: 0.82,95% CI: 0.68-0.98),normal weight(OR: 0.31,95% CI: 0.26-0.37)were significantly associated with a lower risk of incident nonalcoholic fatty liver disease.Participants with more healthy lifestyle factors apparently had lower risks of incident nonalcoholic fatty liver disease.Furthermore,regardless of lifestyles at baseline,changes to more healthy lifestyle factors associated with lower risks of incident nonalcoholic fatty liver disease,while changes to less healthy lifestyle factors associated with higher risks(P for trend < 0.0001),especially the changes in habits of smoking and physical activity.Conclusions This study elaborated the accuracy of fatty liver index for early screening nonalcoholic fatty liver disease.The optimal cut-off point of fatty liver index was ? 30 in the middle-aged and elderly Chinese,with a highly increased risk of incident nonalcoholic fatty liver disease.The development of nonalcoholic fatty liver disease was influenced by age,sex,and metabolic factors.Apparently,lifestyles(current nosmoking,moderate alcohol intake,physically active and normal weight)had a great effect on nonalcoholic fatty liver disease.Participants with more healthy lifestyle factors,a higher healthy lifestyle score,had a lower risk of incident nonalcoholic fatty liver disease.Furthermore,participants who changed to more healthy lifestyle factors were with lower risks of nonalcoholic fatty liver disease,while those changed to less healthy lifestyle factors were with higher risks.