Relationship between triglyceride glucose index and the incidence of non-alcoholic fatty liver disease in the elderly: a retrospective cohort study in China

Objective Non-alcoholic fatty liver disease (NAFLD) is one of the major causes of liver-related diseases, but the relationship between triglyceride glucose (TyG) and NAFLD in the elderly has not been reported yet. In this study, we investigated the role of the TyG index for predicting the incidence of NAFLD in the elderly.

Design and setting This is a prospective cohort study in Henan, China, from 2011 to 2018.

Participants and methods In total, 46 693 elderly people who participated in a routine physical examination programme from 2011 to 2018 were included in this study. TyG index was calculated as ln (fasting triglyceride (mg/dL)×fasting plasma glucose (mg/dL)/2), while NAFLD was defined as hepatic steatosis after excluding other causes based on the results of abdominal ultrasonography; Cox regression model was performed to explore the relationship between TyG index and NAFLD. Also, mediation effect was used to analyse the role of the TyG index in WHtR (waist-to-height ratio) and NAFLD.

Results During the 149 041 person-years follow-up, a total of 5660 NAFLD events occurred (3.80/100 person-years). After adjusting for potential confounding factors, quartile 4 of the TyG index significantly increased the incidence of NAFLD compared with quartile 1, the HRs and 95% CI were 1.314 (1.234 to 1.457). In addition, the TyG index played a partial mediating role in the relationship between WHtR and NAFLD, and the indirect effect was 1.009 (1.006 to 1.011).

Conclusion Higher TyG index was associated with a higher risk of NAFLD in the aged, and therefore, TyG index may be a novel predictor for the incidence of NAFLD. Further, regular examination and evaluation of the TyG index might be useful for controlling the occurrence of NAFLD.