Liver stiffness assessed by transient elastography as a potential indicator of chronic kidney disease in patients with nonalcoholic fatty liver disease

Abstract

Background: This study was designed to determine the diagnostic value of liver stiffness measured by transient elastography (TE) in identifying chronic kidney disease (CKD) in individuals with ultrasonography-diagnosed NAFLD.

Methods: A total of 1439 adult patients with ultrasonography-diagnosed NAFLD between October 2015 and August 2017 in China-Japan union hospital of Jilin university were initially eligible. According to the exclusion criteria, 24 patients were excluded, and eventually, a total of 1415 patients were included in the study. The AST/ALT ratio and FIB-4 score were calculated from blood tests, and liver stiffness was measured using TE.

Results: The liver stiffness measured by TE, FIB-4 score, ALT/AST ratio were significantly elevated in CKD patients, compared with those without CKD (P < 0.001). The areas under the curve (AUROC) of liver stiffness, FIB-4 score and AST/ALT ratio were 0.694 (0.670-0.718), 0.707 (0.682-0.730), 0.712 (0.688-0.736), showing no statistically significant difference between these three tests. Further, multivariate analysis identified four independent risk factors for CKD: age, diabetes mellitus, serum uric acid, and liver stiffness. Also, the performance of these four independent variables taken together in a logistic regression model for identifying CKD was 0.834 (AUROC; 95%CI: 0.814-0.853), showing a higher diagnostic performance than that of a single application of liver stiffness.

Conclusions: Liver stiffness assessed by TE is a potential indicator for CKD in ultrasonography-diagnosed NAFLD patients. Further, a four-variable model (liver stiffness, age, serum uric acid, and diabetes mellitus) could be a useful tool for identifying subjects at high risk for CKD in NAFLD patients.

Keywords: chronic kidney disease; liver stiffness; nonalcoholic fatty liver disease; transient elastography.

Figure 1

Study flow diagram

Figure 2

Boxplots depicting liver fibrosis score in NAFLD patients with or without CKD using three invasive methods (AST/ALT Ratio, FIB‐4 Score, and liver stiffness). The horizontal line inside each box represents the median. The horizontal lines above and below each box encompass the interquartile range (from 25th to 75th percentile), and the vertical lines from the ends of the box encompass the adjacent values (upper: 75th percentile + 1.5 times the interquartile range, lower 25th percentile−1.5 times the interquartile range)

Figure 3

Comparison of ROC curves of AST/ALT Ratio, FIB‐4 Score and liver stiffness for the detection of CKD in NAFLD patients. (A) AST/ALT Ratio, (B) FIB‐4 Score, (C) liver stiffness, (D) Comparison between AST/ALT Ratio, FIB‐4 Score, and liver stiffness. The diagonal line represents detection achieved by chance alone (AUROC = 0.50); the ideal AUROC is 1.00

Figure 4

Comparison of ROC curves of a four‐variable model (liver stiffness, age, serum uric acid, and diabetes status), AST/ALT Ratio, FIB‐4 Score and liver stiffness for the detection of CKD in NAFLD patients. (A) four‐variable model, (B) Comparison between the four‐variable model, AST/ALT Ratio, FIB‐4 Score, and liver stiffness. The diagonal line represents detection achieved by chance alone (AUROC = 0.50); the ideal AUROC is 1.00