Table_2_The role of predicted lean body mass and fat mass in non-alcoholic fatty liver disease in both sexes: Results from a secondary analysis of the NAGALA study.DOCX

ObjectiveHigh body mass index (BMI) is an important risk factor for non-alcoholic fatty liver disease (NAFLD). However, the association of body composition such as fat mass (FM) and lean body mass (LBM) with NAFLD has not been adequately studied. The purpose of this study was to clarify the contribution of body composition FM and LBM to NAFLD.
MethodsWe analyzed data from 7,411 men and 6,840 women in the NAGALA cohort study. LBM and FM were estimated for all subjects using validated anthropometric prediction equations previously developed from the National Health and Nutrition Examination Survey (NHANES). Using multiple logistic regression and restricted cubic spline (RCS) to analyze the association and the dose-response curve of predicted LBM and FM with NAFLD in both sexes.
ResultsThe prevalence of NAFLD in man and woman subjects was 27.37 and 6.99%, respectively. Predicted FM was positively and linearly associated with NAFLD in both sexes, with each 1 kg increase in predicted FM associated with a 27 and 40% increased risk of NAFLD in men and women, respectively. In contrast, predicted LBM was negatively associated with NAFLD in both sexes, with each 1 kg increase in predicted LBM reducing the risk of NAFLD by 4 and 19% in men and women, respectively. In addition, according to the RCS curve, the risk of NAFLD did not change in men when the predicted LBM was between 47 and 52 kg, and there seemed to be a saturation effect; further, the threshold value of the saturation effect was calculated to be about 52.08 kg by two-piecewise logistic regression, and the protective effect on NAFLD would be significantly enhanced when the man predicted LBM was greater than 52.08 kg.
ConclusionThe current findings suggested that body composition LBM and FM had opposite associations with NAFLD in both sexes, with higher LBM associated with a lower risk of NAFLD and higher FM increasing the risk of NAFLD, especially in women.

研究背景与目的：高体重指数（BMI，Body Mass Index）是非酒精性脂肪性肝病（NAFLD，Non-Alcoholic Fatty Liver Disease）的重要危险因素。然而，目前针对脂肪量（FM，Fat Mass）与去脂体重（LBM，Lean Body Mass）等身体成分与NAFLD的关联研究仍不够充分。本研究旨在明确身体成分中FM与LBM对NAFLD的贡献价值。
研究方法：本研究分析了NAGALA队列研究中7411名男性与6840名女性的研究数据。所有受试者的LBM与FM均通过经美国国家健康与营养调查（NHANES，National Health and Nutrition Examination Survey）开发并验证的人体测量学预测方程进行估算。本研究采用多重logistic回归与限制性立方样条（RCS，Restricted Cubic Spline）模型，分析两性中估算得到的LBM、FM与NAFLD的关联及剂量反应曲线。
研究结果：本研究中男性与女性受试者的NAFLD患病率分别为27.37%与6.99%。在两性中，估算得到的FM均与NAFLD呈正线性相关：估算FM每增加1kg，男性与女性的NAFLD发病风险分别升高27%与40%。与之相反，估算LBM则与NAFLD呈负相关：估算LBM每增加1kg，男性与女性的NAFLD发病风险分别降低4%与19%。此外，通过RCS曲线分析可见，当男性估算LBM处于47~52kg区间时，NAFLD发病风险无明显变化，呈现饱和效应；进一步通过分段logistic回归计算得到该饱和效应的阈值约为52.08kg，当男性LBM超过该阈值时，其对NAFLD的保护作用会显著增强。
研究结论：本研究结果表明，两性身体成分中的LBM与FM对NAFLD的关联方向完全相反：更高的LBM对应更低的NAFLD发病风险，而更高的FM则会升高NAFLD发病风险，这一现象在女性群体中尤为显著。