[Relationship between waist circumference trajectory and new-onset non alcoholic fatty liver disease in the non-obese population].

Objective: To investigate the relationship between waist circumference trajectory and new-onset nonalcoholic fatty liver disease (NAFLD) in the non-obese population. Methods: The study cohort was composed of the ones who met the selection criteria in Kailuan study. Waist circumference trajectories of the participants in 2006-2007, 2008-2009 and 2010-2011 were determined by SAS Proc Traj program. Four groups with different waist circumference trajectories were generated, including low-, medium-, medium-high- and high-stability groups. All groups were followed up for their health conditions in 2012-2013, 2014-2015 and 2016-2017, respectively. Incidence rates of NAFLD during physical examination were compared among different waist circumference trajectory groups. Cox regression model was used to analyze the correlation between different waist circumference trajectory groups and new-onset NAFLD. Results: Finally, 12 477 observers were included in the statistical analysis, including 8 181 males and 4 296 females. There were 1 026 (8.2%), 5 183 (41.5%), 5 481 (44.0%) and 787 cases (6.3%) in the low, medium, medium-high and high stability-stability groups, respectively. There were 4 123 NAFLD cases occurred during the follow-up period. The cumulative incidence of NAFLD increased along with the increase of waist circumference trajectory (21%, 43%, 59%, 72%, respectively) (P<0.01). The risks of NAFLD were 2.411 (95%CI: 2.021-2.877), 4.050 (95%CI: 3.402-4.820) and 5.489 (95%CI: 4.506-6.686) times higher in medium-, medium-high- and high-stability group than that in the low-stability group (P<0.01). After adjusting for age, sex and other confounding factors, the risks of NAFLD in the medium-, medium-high- and high-stability groups were 2.150 (95%CI: 1.789-2.582), 3.176 (95%CI: 2.623-3.846) and 3.732 (95%CI: 2.987-4.662) times higher than that in the low-stability group. Conclusion: The risk of NAFLD in non-obese people increased along with the increase of waist circumference trajectory, which seemed to have played an independent risk factor for NAFLD.