Epidemiological characteristics of nonalcoholic fatty liver disease with elevated alanine aminotransferase and related risk factors

Objective To investigate the epidemiological characteristics of nonalcoholic fatty liver disease ( NAFLD) with elevated alanine aminotransferase ( ALT) and related risk factors. Methods A total of 1007 patients with NAFLD who were admitted to The Affiliated Hospital of Logistics University of Chinese People's Armed Police Forces from April 4, 2016 to September 13, 2016 were enrolled, and among these patients, 123 had an elevated ALT level ( higher than the upper limit of normal 50 U/L) ( elevated ALT group) and 884 had normal ALT ( normal ALT group) . A statistical analysis was performed for their general data and laboratory markers [number of peripheral blood mononuclear cells, fasting blood glucose, triglyceride ( TG) , total cholesterol ( TC) , high-density lipoprotein ( HDL) , low-density lipoprotein ( LDL) , LDL/HDL ratio, ALT, aspartate aminotransferase ( AST) , gamma-glutamyl transpeptidase ( GGT) , alkaline phosphatase ( ALP) , uric acid ( UA) , creatinine, blood urea nitrogen, urinary protein, urinary microproteins], blood pressure, body mass index ( BMI) , concomitant biliary disease, and thyroid nodules. The t-test was used for comparison of normally distributed continuous data between groups, and the Mann-Whitney U test was used for comparison of non-normally distributed continuous data between groups; the chi-square test was used for comparison of categorical data between groups. A multivariate logistic regression analysis was used to identify the risk factors for elevated ALT in NAFLD patients. Results Among the 1007 patients with NAFLD, there were 752 male and 255 female patients.Of all male patients, 13. 7% ( 103/752) were in the elevated ALT group, and of all female patients, 7. 8% ( 20/255) were in the elevated ALT group; there was a significant difference in the prevalence rate between male and female patients ( χ2= 5. 552, P = 0. 018) . According to the age, the 1007 patients were divided into 20-39 year group with 242 patients, 40-59 year group with 555 patients, and 60-90 year group with 210 patients, and there was a significant difference in the proportion of patients with an elevated ALT level between these three groups ( 26. 03% vs 8. 83% vs 5. 24%, χ2= 52. 327, P < 0. 001) ; further comparison between any two groups showed that the 20-39 year group had a significantly higher proportion of patients with an elevated ALT level than the 40-59 year group and the 60-90 year group ( χ2= 39. 886 and 34. 009, both P < 0. 001) . Most patients in the elevated ALT group were young and middle-aged adults, and compared with the normal ALT group, the elevated ALT group had a significantly younger age and a significant higher BMI ( t = 7. 419 and-4. 595, both P < 0. 001) ; there were also significant differences between the two groups in UA, number of peripheral blood mononuclear cells, LDL/HDL ratio, HDL, AST, and GGT ( U = 42 942, 47 697, 48 106, 49 086, 31 938, and 36 283, all P < 0. 05) . Of all 1007 patients, 392 had NAFLD complicated by thyroid nodules, and the elevated ALT group had a significantly higher proportion of such patients than the normal ALT group ( 40. 2% vs 30. 1%, P < 0. 05) . The univariate analysis showed that male sex, age ( young and middle ages) , a high number of peripheral blood mononuclear cells, increased LDL/HDL ratio, a low level of HDL, a high level of GGT, a high BMI, and absence of thyroid nodules were associated with elevated ALT in NAFLD patients ( all P < 0. 05) . The multivariate logistic regression analysis showed that young and middle ages ( 20-39 years) , a high number of peripheral blood mononuclear cells, and a high level of GGT were independent risk factors for elevated ALT in NAFLD patients ( all P < 0. 001) . Conclusion Young and middle ages ( 20-39 years) , a high number of peripheral blood mononuclear cells, and a high level of GGT are predictive factors for elevated ALT in NAFLD patients and may have a certain value in guiding the early diagnosis of nonalcoholic steatohepatitis.