To clarify the association between serum high density lipoprotein cholesterol (HDL-C) and the incidence rate of nonalcoholic fatty liver disease (non-alcoholic fatty liver disease).

Logistic regression model was used to evaluate the association between baseline serum HDL-C level and the occurrence of nonalcoholic fatty liver disease (NAFLD) in Japanese population. The dose-dependent relationship between HDL-C and NAFLD was analyzed by smooth curve fitting. The threshold effect of HDL-C and NAFLD was found by piecewise linear regression model.

A total of 15 464 people were enrolled in the study, and 2 741 cases were diagnosed as nonalcoholic fatty liver disease. After adjusting for age, gender, smoking status, alcohol intake, BMI, HbA_1c and TC, the risk of non-alcoholic fatty liver disease in middle and high-level participants was reduced to 85% and 47% of the incidence of NAFLD in low-level participants [OR=0.85 (0.73, 0.98) and 0.47 (0.38, 0.58)]. Smooth curve fitting showed that when HDL-C＜2.19 mmol/L, the risk of non-alcoholic fatty liver disease decreased with the increase of HDL-C [HR 0.19 (0.15, 0.23), P＜0.0001], but when HDL-C＞2.19 mmol/L, the risk was not significantly associated [HR 2.24 (0.78, 6.44) P=0.1358].

The incidence rate of HDL-C is correlated with the incidence of nonalcoholic fatty liver disease. The higher the HDL-C level, the lower the incidence rate of non-alcoholic fatty liver disease. When HDL-C＞2.19 mmol/L, the correlation was not obvious.