New Model to Predict Fibrosis in Obese Patients
A better way to screen for fibrosis in NAFLD? Researchers propose a new method at DDW 2018. Dr. Arthur McCullough explains.
Nonalcoholic fatty liver disease (NAFLD) affects about one-third of the adult population in the United States. Despite its prevalence, many patients don’t realize they have it. While awareness has increased about NAFLD, there is still a knowledge gap. Not enough physicians are diagnosing nor closely monitoring the patients who have it, says Cleveland Clinic gastroenterologist and hepatologist Arthur McCullough, MD.
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Fatty liver disease can progress to fibrosis, and eventually to cirrhosis, if not treated. While there are ways to screen patients with fatty liver disease to determine if they have fibrosis, the existing methods for determining the degree of scarring in the liver are problematic, especially for certain patient populations.
The prevailing method is liver biopsy — a procedure that is expensive, invasive and comes with risks for the patient. Those risk factors only increase when you consider that the majority of patients with NAFLD have other comorbidities, often related to weight. About 90 to 95 percent of people with NAFLD are overweight, with a large percentage being obese or morbidly obese.
That leads to the second problem. Currently, the noninvasive methods that try to predict how much scarring is in the liver include APRI, BARD, FIB-4 and NAFLD fibrosis scores. The issue is that these models haven’t been studied in obese or morbidly obese individuals — arguably, the population that most needs an accurate picture of their fibrosis risk.
“We knew that we needed to create a predictive index for those patients with a BMI above the 35 range,” says Dr. McCullough, who co-authored the paper, Comparison of Prediction Models of Advanced Fibrosis in morbidly and non-morbidly Obese Patients with Nonalcoholic Fatty Liver Disease, along with Tavankit Singh, MD; Catherine Frakes, DO; and Rocio Lopez, MS.
Their study analyzed 1,969 morbidly obese patients with NAFLD proven by biopsy. The research team split patients into two groups to compare a new predictive index for obese and morbidly obese patients with NAFLD with the existing models.
This new predictive index looked at four factors:
Based on those four factors, the model calculated an obesity fibrosis score (OFS). The results were clear: When the team compared the OFS with other models, the OFS was the best predictor of fibrosis in those with a BMI of over 35.
What about predicting fibrosis for those with a BMI under 35? They tested that, too, and found that OFS had the same accuracy as the other models.
Because OFS provided greater accuracy in those with a BMI of over 35 and equivalent accuracy for those with a BMI under 35, the research team sees great potential for OFS. “We are proposing OFS be the preferred model for all patients,” Dr. McCullough says.
While specialists may be involved, more often than not, screening for fibrosis falls to primary care physicians.
“I would advise the physician order an ultrasound on any obese patient, and if the scan shows that they have fatty liver disease, the physician should immediately think about fibrosis,” Dr. McCullough suggests.
Ultimately, OFS is a preventive screening tool. “When we know about a patient’s risk for fibrosis, we can delay development of it,” he says. While there isn’t an FDA-approved drug for fibrosis, his group has had success with what he calls a “fatty liver cocktail,” which is essentially a group of supplements and medications that may ward off fibrosis — and ultimately, cirrhosis.
Ultimately, Dr. McCullough would like to see OFS combined with using FibroScan® (Echosens, Paris), a machine that sends ultrasound waves through the liver to predict fibrosis. The scan has not always been accurate in obese and morbidly obese people because of the specific probe used. But now, Dr. McCullough says, a new probe has been developed that will be more accurate for those with a BMI of 35 or greater.
For now, using OFS will be a very important first step toward being able to predict fibrosis in the majority — rather than the minority — of patients with NAFLD.
“With this, we should be able to avoid doing liver biopsies in 80 percent in NAFLD patients,” Dr. McCullough says.
Dr. McCullough presented his research on Tuesday at DDW 2018. He hopes to launch an OFS online calculator by the end of 2018, so physicians can easily use the model for NAFLD patients.