This study was conducted to investigate the incidence rate of fatty liver and it's related factors based on a three year follow up of multiphasic health screening participants.

671 male workers who had participated in both initial and second multiphasic health screening were selected. Initial screening was performed during the year of 1996 to 1997 and second screening was performed during the year of 1999 to 2000. Among them, four hundred and thirty workers who didn't initially have a fatty liver were selected as the final study subjects. They were classified into 2 categories according to the initial and second hepatic ultrasonographic findings; stationary normal(307, 71.4%), and fatty liver incident(123, 28.6%). The incidence rate was calculated using the incidence density method.

The incidence rate of fatty liver among the male workers was 9.73 per 100 person-years. The white collar workers had a higher incidence rate(10.66) than the blue collar workers(8.14). The incidence density ratio of alcohol drinking to fatty liver incidence was 1.41, and the incidence density ratio of low vegetable diet was 1.63. The incidence density ratio of obesity was 1.78 for the 100-109% obesity index group, 2.83 for the 110-119% obesity index group, 4.25 for the >or=120% obesity index group over <100%. Smoking, regular exercise, salty food preference, and taking food supplement had no significant effect on the incidence of fatty liver. The fatty liver incident group had higher initial blood pressure, GPT, gamma GTP, fasting blood sugar, HbA1c, uric acid, total cholesterol and triglyceride levels than the stationary normal group. However, there were no differences in the GOT, HDL-cholesterol or LDL-cholesterol levels. In the multiple logistic regression analysis, obesity index and serum triglyceride were found to be major factors in the incidence of fatty liver after controlling age, alcohol drinking, vegetable diet, daily coffee intake, blood pressure, HbA1c, total cholesterol, and uric acid levels.

The incidence rate of fatty liver among the male workers was 9.73 per 100 person-years. The lifestyles which gave rise to an increasing incidence of fatty liver were those involving excessive alcohol drinking, obesity, and low vegetable diet. Moreover, many cardiovascular disorder related health indices such as blood pressure, and the blood sugar, blood lipid and uric acid levels, were related to the incidence of fatty liver.