[A cohort study on the correlation between body mass index trajectories and new-onset non-alcoholic fatty liver disease].

Objective: To explore the correlation between the body mass index (BMI) trajectories and new-onset non-alcoholic fatty liver disease (NAFLD) so as to provide a scientific basis for the prevention and treatment of NAFLD. Methods: A total of 16388 observation subjects that met the inclusion criteria in the Kailuan study were used to form a cohort study. According to the BMI values of the observed subjects during annual physical examinations from 2006 to 2007, 2008 to 2009 and 2010 to 2011, SAS Proc Traj was used to determine four different BMI trajectories groups, namely, the low-stable medium-stable, medium-high and high-stable group. NAFLD incidence in each group was followed up during annual physical examinations from 2012 to 2013, 2014-2015 and 2016-2017. A total of 14998 observation subjects were finally included in the statistical analysis. The cumulative incidences of NAFLD differences in the four groups were compared. The Cox's proportional hazards regression model was used to analyze the correlation between different BMI trajectories and new-onset NAFLD. One-way analysis of variance was used to compare the intergroup difference of measurement data, and pairwise comparisons were conducted. LSD test was used for the homogeneity of variance. Dunnett's T3 test was used for heterogeneity of variances. χ (2) test was used to compare the count data, and the difference of NAFLD cumulative incidence rate between the different BMI trajectories groups was compared by log-rank test. Results: (1) the cumulative incidence of NAFLD was increased with the increase of BMI trajectories, which were 31%, 47%, 63%, 77%, respectively, and the difference was statistically significant (P < 0.01). (2) after adjusting for multiple confounding factors such as age and gender with the Cox's proportional hazards regression model, the risk of NAFLD in the BMI medium stable, medium-high, and high stable group was still 1.757 times [95% confidence interval (CI): 1.589 ~ 1.942], 2.612 (95%CI: 2.353 ~ 2.900), 3.566 (95%CI: 3.129 ~ 4.064) of the low-stable group (P < 0.01). Conclusion: The risk of NAFLD increases with increase of BMI trajectories, and long-term high levels of BMI are independent risk factors for the onset of NAFLD.目的： 探讨体质量指数（BMI）轨迹与新发非酒精性脂肪性肝病（NAFLD）的相关性，为NAFLD的防治提供科学依据。 方法： 以开滦研究中符合入选标准的16 388例观察对象组成研究队列，依据观察对象2006-2007、2008-2009、2010-2011年度健康体检的BMI数值，用SAS Proc Traj程序确定4个不同的BMI轨迹组，分别为低稳定组、中稳定组、中高稳定组、高稳定组，随访各组人群2012-2013、2014-2015、2016-2017年度健康体检时NAFLD的发病情况。最终纳入统计分析的观察对象共14 998例，比较4组NAFLD累积发病率的差异，用Cox比例风险回归模型分析不同BMI轨迹与新发NAFLD的相关性。计量资料组间比较采用单因素方差分析，并进行两两比较，方差齐用LSD检验，方差不齐则用Dunnett’s T3检验；计数资料的比较用χ(2)检验；用Log-rank检验比较不同BMI轨迹组NAFLD累积发病率的差异。 结果： NAFLD的累积发病率随着BMI轨迹的升高而增加，分别为31%、47%、63%、77%，差异有统计学意义（P < 0.01）。用Cox比例风险回归模型校正年龄、性别等多种混杂因素后，BMI中稳定组、中高稳定组、高稳定组NAFLD发病风险仍为BMI低稳定组的1.757[95%可信区间（CI）：1.589～1.942]、2.612（95%CI：2.353～2.900）、3.566（95%CI：3.129～4.064）倍（P < 0.01）。 结论： 发生NAFLD的风险随着BMI轨迹的升高而增加，BMI长期高水平是NAFLD发病的独立危险因素。.