FIB-4: An Inexpensive and Accurate Marker of Liver Fibrosis in Patients with Hepatitis C

While liver biopsy is considered the "gold standard" for assessing liver fibrosis, the procedure is expensive and is associated with a small risk of complications including excessive bleeding. Therefore, researchers have developed a variety of non-invasive biomarker and imaging methods to reduce the need for biopsies.

As reported in the June 13, 2007 advance online edition of Hepatology, French researchers performed a study to validate a non-invasive test called FIB-4 -- which combines patient age and 3 standard biochemical values, platelet count, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) -- in HCV monoinfected patients who received 847 liver biopsies. They also compared the results of 780 FIB-4 and FibroTest assays performed on the same day in 592 patients with HCV. FibroTest combines patient age and sex with 5 biomarkers: alpha2-macroglobulin, haptoglobin, apolipoprotein A1, total bilirubin, and gamma-glutamyl transpeptidase (GGT).

Results

• The FIB-4 index correctly identified patients with severe fibrosis or cirrhosis (stage F3-F4), with areas under the receiver operating characteristic curve (AUROCs) of 0.85 and 0.91, respectively.

• A FIB-4 index score below 1.45 had a negative predictive value of 94.7% and a sensitivity of 74.3% for excluding severe fibrosis.

• A FIB-4 score higher than 3.25 had a positive predictive value of 82.1% and a specificity of 98.2% for confirming the existence of severe fibrosis.

• Using these cut-offs, 72.8% of the 847 liver biopsies were correctly classified.

• The FIB-4 index was strongly correlated with FibroTest results for scores below 1.45 or above 3.25 (P < 0.01).

• A FIB-4 value below 1.45 or above 3.25 (which accounted for 64.6% of all cases) was concordant with FibroTest results in 92.1% and 76% of cases, respectively.

Conclusion

In conclusion, the authors wrote, "For values outside [the] 1.45-3.25 [range], the FIB-4 index is a simple, accurate, and inexpensive method for assessing liver fibrosis and proved to be concordant with FibroTest results."

This study confirms previous data showing that while non-invasive methods perform well at distinguishing between absent or mild fibrosis and extensive fibrosis or cirrhosis, they do less well at distinguishing between intermediate stages.

07/03/07

Reference
A Vallet-Pichard. V Mallet, B Nalpas, and others. FIB-4: An inexpensive and accurate marker of fibrosis in HCV infection: comparison with liver biopsy and Fibrotest. Hepatology 46(1): 32-336. June 13, 2007 [Epub ahead of print].