A study on the risk factors of nonalcoholic fatty liver disease in military aircrews

Abstract

Objective To analyze the pathogenetic status and risk factors of nonalcoholic fatty liver disease (NAFLD) in military airerews, in order to provide evidence for the treatment and prevention of NAFLD. Methods The study included collecting data as military airerew's age, flying hours and type of aircraft, calculating body mass index (BMI), measuring liver function [alanine transaminase (ALT), aspartase aminotransferase (AST), gamma-glutamyltransferase (GGT)], fasting blood glucose (FBG), uric acid (UA), total cholesterol (TC), triglyceride(TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (HDL-C), as well as examining liver by B-ultrasound. Results were processed by variance and Logistic regression analysis according to the groups that respectively divided by NAFLD (2 groups), BMI value (2 groups) and ALT value (3 groups by the ranges within ALT<40 U/L, 40 U/L≤ALT<80 U/L and ALT≥ U/L). Results Out of 426 male aircrews, 34.98% were overweight, 19.48% had NAFLD and 16.67% were with high ALT. Compared with normal weight group, morbidity rate of NAFLD and level of ALT were significantly higher than those in over weight group (X2=145.152, 58.959, P< 0.01). Aircrews in ALT≥40 U/L group showed statistical differences on BMI and TG compared to those in ALT<40 U/L group (F=13.476, 13.176, P<0.01). ATL, AST, C, GT, TG, TC, LDL-C, FBG and UA in NAFLD group were significantly higher than those in control group (t= 2.287-7.002, P<0.05 or 0.01), but HDL-C level was significantly lower (t=2.932, P<0.01). There were no statistical differences between fast jet and low speed aircraft (transporter, bomber, helicopter, etc.) aircrews in age, flying hours, BMI and other biochemical indexes. Logistic regression analysis showed that the factors that induced NAFLD were BMI, TG and type of aircraft (Z=37.353, 8.658, 4.486, P<0.05 or 0.01). Conclusions The aircrews have higher morbidity rate of NAFLD with such high risk factors as over weight, high blood lipid (high TG, high LDL-C and low HDLC). So early diagnosis and treatment of NAFLD would be one of the most important measures for limiting its growth and preventing cardiovascular and cerebrovaseular diseases. Key words: Fatty liver; Alanine transaminase; Body mass index; Overweight; Hyperlipidemias; Factor analysis, statistical