Factors affecting the diagnostic accuracy of ultrasonography in assessing the severity of hepatic steatosis

Background/purpose: Ultrasonography has long been recognized as a useful tool for detecting hepatic steatosis in clinical practice. However, whether it can assess the severity of hepatic steatosis and which factors affect its diagnostic accuracy remain unclear.

Methods: A total of 171 patients with various causes of hepatitis undergoing liver biopsies were retrospectively reviewed. The clinical, serologic data and ultrasonographical findings were recorded. Hepatic steatosis was graded as negative, mild, moderate, or severe by ultrasonography and histology. Histology was used as gold standard and the agreement rates were calculated.

Results: Our data showed that the agreement rate of ultrasonography was 61.4% in assessing the severity of hepatic steatosis and 74.3% in diagnosing hepatic steatosis compared with histology (crude kappa=0.46 vs. 0.46). Using univariate analyses, body mass index and histology activity index score were associated with the agreement in assessing the severity of hepatic steatosis (p=0.008 and 0.035), whereas Ishak fibrosis score had a trend association (p=0.066). Multivariate analyses indicated that age, body mass index, and Ishak fibrosis score could affect the agreement (odds ratio=0.72, 0.89, and 1.41; 95% confidence interval=0.54-0.97, 0.83-0.97, and 1.1-1.8).

Conclusion: Ultrasonography could assess the severity of hepatic steatosis with moderate accuracy. Obese patients are difficult ultrasonographically. In addition, age and hepatic fibrosis could affect the performance of ultrasonography in assessing the severity of hepatic steatosis.