Systematic review with meta-analysis: non-invasive assessment of non-alcoholic fatty liver disease--the role of transient elastography and plasma cytokeratin-18 fragments.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) affects 15-40% of the general population. Some patients have non-alcoholic steatohepatitis (NASH) and progressive fibrosis, and would be candidates for monitoring and treatment. AIM: To review current literature on the use of non-invasive tests to assess the severity of NAFLD. METHODS: Systematic literature searching identified studies evaluating non-invasive tests of NASH and fibrosis using liver biopsy as the reference standard. Meta-analysis was performed for areas with adequate number of publications. RESULTS: Serum tests and physical measurements like transient elastography (TE) have high negative predictive value (NPV) in excluding advanced fibrosis in NAFLD patients. The NAFLD fibrosis score comprises of six routine clinical parameters and has been endorsed by current American guidelines as a screening test to exclude low-risk individuals. The pooled sensitivities and specificities for TE to diagnose F ≥ 2, F ≥ 3 and F4 disease were 79% and 75%, 85% and 85%, and 92% and 92% respectively. Liver stiffness measurement often fails in obese patients, but the success rate can be improved with the use of the XL probe. A number of biomarkers have been developed for the diagnosis of NASH, but few were independently validated. Serum/plasma cytokeratin-18 fragments have been most extensively evaluated and have a pooled sensitivity of 66% and specificity of 82% in diagnosing NASH. CONCLUSIONS: Current non-invasive tests are accurate in excluding advanced fibrosis in NAFLD patients, and may be used for initial assessment. Further development and evaluation of NASH biomarkers are needed.

Assessment of non-alcoholic fatty liver disease using serum total cell death and apoptosis markers.

BACKGROUND: The diagnosis of non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and fibrosis relies on liver biopsy. Non-invasive assessments are urgently needed. AIM: To evaluate cell apoptotic marker cytokeratin-18 M30 and total cell death markers cytokeratin-18 M65/M65ED for the assessment and monitoring of NAFLD. METHODS: A cohort of 147 patients with biopsy-proven NAFLD and 73 controls were enrolled, including 51 patients who received paired liver biopsies 36 months apart. Biomarkers were determined by enzyme-linked immunosorbent assay. RESULTS: M30, M65 and M65ED increased in a stepwise fashion in control subjects, patients with non-NASH, NAFLD and NASH (all P < 0.001). All biomarkers had similarly high accuracy over 0.9 in predicting NAFLD and moderate accuracy around 0.7 in predicting NASH. Among patients with paired liver biopsies, changes in M30, M65 and M65ED positively correlated with disease progression (rho = 0.42, 0.32 and 0.39; P = 0.002, 0.023 and 0.005 respectively), and only changes in M65 and M65ED correlated with fibrosis progression (rho = 0.29, 0.34; P = 0.038, 0.015 respectively). Both M30 and M65 had area under receiver-operating characteristics curve above 0.8 in predicting disease progression. At cut-off of 236 U/L, changes of M65ED had 88% NPV and 59% PPV to exclude and predict fibrosis progression. CONCLUSIONS: Cytokeratin-18 M30 and M65/M65ED have moderate accuracy in detecting non-alcoholic steatohepatitis. Changes in the biomarkers also correlate with histological progression. However, development of new biomarkers is still required to improve the diagnostic accuracy.