What is Fatty Liver Disease?
Fatty liver disease is a condition that is characterized by a buildup of excess fat in the liver. It is usually asymptomatic but rarely may present with fatigue or right upper quadrant abdominal pain. Despite being asymptomatic, Fatty liver disease needs to be diagnosed early in order to prevent it from progressing to fatal conditions such as liver cirrhosis, carcinoma, and hematemesis secondary to esophageal varices.
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Fatty Liver disease is classified based on the underlying etiology, non-alcoholic fatty liver disease, and alcoholic liver disease. Major risk factors for fatty liver disease are obesity, alcohol, and diabetes. Diagnosis is often delayed due to the nonspecific nature of the symptoms. Definite diagnosis requires laboratory tests, imaging tests, and liver biopsy.
The Fibrosis-4 score is a score to determine the extent of liver scarring. Liver fibrosis rarely progresses on a linear scale so assessment of progress in fibrosis over time is essential. However, using invasive tests and repeated imaging may not be a preferable option for most patients which is where Fib-4 comes in. Fib-4 was initially developed for non-invasive evaluation of liver fibrosis in HIV and HCV co-infection.
Fib-4 classifies the degree of fibrosis at three levels:
- Mild Fibrosis: 0-2
- Moderate Fibrosis: 3-4
- Severe Fibrosis: 5-6
When is Fib -4 used?
- Patients with liver diseases including chronic hepatitis, alcoholic liver disease, fatty liver disease, metabolic, and cholestatic liver diseases.
- Known case of liver fibrosis to evaluate disease progression
Why is it preferred over other liver tests?
Despite being the gold standard, biopsy only samples a small portion of the liver but fibrosis involves extensive areas of the liver. In addition, biopsy being an invasive test can come with significant morbidity. Liver cirrhosis requires highly sensitive tests and the FIB-4 score has been shown to be superior to more than seven noninvasive fibrosis markers.
Study to evaluate FIB-4 score’s efficacy
Researchers used data collected from blood samples of 40,000 people between 1985 and 1996. The decade-long study concluded that repeated measurements of the FIB-4 score were more predictive of liver cirrhosis than a single measurement of the FIB-4 score.
“It is difficult to predict the risk of cirrhosis, although you can get some guidance in using regular blood tests that measure liver damage,” says lead author Hannes Hagstrom, a hepatologist at the Karolinska University Hospital and docent at Karolinska Institutet. “Therefore, we wanted to investigate whether what is known as the FIB-4 score can increase the accuracy of the identification of people at high risk, in particular with information from repeated measurements.”
The study’s most important conclusion was that the FIB-4 score correlated with disease severity but the major drawback was the relatively low accuracy of the FIB-4 test.