[The prevalence of non-alcoholic fatty liver disease and its related risk factors in 1180 school children in Shanghai].

OBJECTIVE: To evaluate the prevalence of non-alcoholic fatty liver disease (NAFLD) and its related risk factors in children in Shanghai.

METHODS: A total of 1180 students aged 6 to 14 years (9.0+/-1.9) y from two elementary schools in the Pudong New Area were enrolled in our study, 572 were male and 608 were female. Height, body weight, waist circumference, hip circumference, waist-hip ratio (WHR), blood pressure were measured and liver ultrasound B scans were analyzed for each student. Body mass index (BMI) was calculated as body weight in kilograms divided by the square of height in meters.

RESULTS: Liver ultrasonic images were normal in 1155 students (97.9%), 18 students had mild fatty livers (1.5%) and 7 (0.6%) students had moderate fatty livers, while none of the students had severe fatty livers. Of all the NAFLD students, 19 were male and 6 were female. The prevalence of NAFLD in male students was obviously higher compared with that in female students (X2=6.66, P<0.05). The number of students with normal BMI was 934 (79.2%), while 137 (11.6%) and 109 (9.2%) respectively were overweight and obese, according to the age and gender specific BMI chart for Chinese children. The prevalence of NAFLD in students with normal BMI was 0.6% (6/934), while it was 2.9% (4/137) and 13.8% (15/109) in overweight and obese students. The prevalence of NAFLD in overweight and obese students was higher than that in students with normal BMI (X2=85.93, P<0.01). All the students were further divided into two groups based on age: group 1, 714 prepubertal students age 6 to 9 years; group 2, 466 students in puberty stage age 10 to 14 years. The prevalence of NAFLD was 1.7% (12/714) in group 1 and 2.8% (13/466) in group 2. There was no statistical difference between the two groups (X2=2.01), P>0.05. A stepwise multiple regression analysis was performed to evaluate the relationship between NAFLD and its related factors. BMI and WHR were chosen as predictors of NAFLD (x2=69.35), P<0.01.

CONCLUSION: Based on liver ultrasound, the prevalence of NAFLD is 2.1% of the 1180 surveyed school students age 6 to 14 years. The prevalence of NAFLD was obvious higher in overweight and obese students compared with that in students with normal BMI. Male students had more NAFLD than female students. BMI and WHR could be used as effective indexes to predict the occurrence of NAFLD.