Going beyond liver biopsy to predict liver damage
Nonalcoholic fatty liver disease (NAFLD) is a range of conditions as a result of fat build up in the liver.
Initially there are no signs or symptoms of the disease, so most persons are unaware that they have the condition. Generally fatty liver disease, if left untreated, can progress to scarring of the liver tissue leading to scarring (fibrosis) and eventually to cirrhosis, and even liver failure. Liver fibrosis is the primary predictor of liver‐related deaths in NAFLD.
The key diagnostic challenge in NAFLD is to accurately detect and to quantify the degree of fibrosis to identify those at highest risk for liver‐related complications. Identifying patients with early‐stage fibrosis is key to implementing risk‐reduction strategies to prevent disease progression.
NAFLD occurs mainly in persons who are obese and potentially may also have other diseases such as metabolic syndrome, which includes central adiposity, hypertension, dyslipidemia, and insulin resistance.
The degree of fibrosis is currently determined by liver biopsy, the gold standard for diagnosing NAFLD, which is limited by the risk associated with an invasive procedure, cost, and sampling error.
Noninvasive diagnostic methods allow for classifying the risk of patients and to select those who would benefit most from liver biopsy, while potentially avoiding this invasive procedure in others.
The noninvasive methods currently employed include APRI, BARD, FIB-4 and NAFLD fibrosis scores that can predict the degree of scarring. However, these methods have not been applied to obese individuals that carry a higher risk for NAFLD.
Recently, the Cleveland Clinic, USA, have developed a new model to predict fibrosis in persons whose body mass index (BMI) was greater than 35 (morbid obesity).
The team analyzed 1,969 morbidly obese patients with NAFLD proven by liver biopsy to come up with a predictive obesity fibrosis score (OFS). This was based on 4 clinical parameters:
- Presence of diabetes
- Presence of hypertension
- Platelet count in the blood
- AST level (aspartate aminotransferase, a liver enzyme)
Dr. Arthur McCullough and his team found that OFS score was the best predictor of fibrosis in those persons with NAFLD and with a BMI of over 35 when compared to the currently available models.
They also tested persons whose BMI was less that 35 and found that OFS score worked just as efficiently in predicting fibrosis.
The new model could become a valuable tool in screening patients showing fatty liver in ultrasound scans. Once a patient’s risk for fibrosis is known, the progress must be halted into developing further. While there is no FDA-approved drug for fibrosis, a “fatty liver cocktail,” which is essentially a group of supplements and medications may ward off fibrosis — and ultimately, cirrhosis.
Calculating OFS in conjunction with Fibro scan using a new probe devised specially to be used in obese patients can accurately predict the degree of fibrosis. Fibro scan is a machine that sends ultrasound waves through the liver to predict fibrosis, already used in many large hospitals. This can help in avoiding liver biopsies in majority of patients.