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Over 90% at Risk for Fibrotic NASH Don't Need Liver Specialist
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AASLD-The Liver Meeting, November 4-8, 2022, Washington, DC
Mark Mascolini
A simple algorithm (decision tree) applied to a representative US population at risk for fibrotic nonalcoholic steatohepatitis (NASH) determined that only 8% of them needed referral to a liver specialist [1]. Researchers from Arizona Liver Health and other centers believe the results mean most people at risk for fibrotic NASH can be cared for by primary providers without referral to hepatologists.
Recent research determined that nonalcoholic fatty liver disease (NAFLD) affects 38% of middle-aged people in the United States and NASH, a more advanced condition, affects 14% of middle-aged people. Health experts figure the US has 95 million people with NAFLD and 7500 hepatologists. That comes to more than 12,600 NAFLD patients per liver doctor if everyone with NAFLD saw a specialist.
To figure how many people with NAFLD really need a hepatologist, the American Gastroenterological Association (AGA) proposed a NAFLD "Clinical Care Pathway" algorithm. The pathway helps primary care providers screen people who risk fibrotic NASH (NASH with F2 to F4 fibrosis) to judge whether they should refer that person to a liver expert [2].
The AGA algorithm uses two standard liver function gauges in sequence-FIB-4 index and liver stiffness measurement (LSM) by transient elastography (FibroScan). A person at risk for NAFLD with advanced fibrosis (having 2 or more metabolic risk factors, or type 2 diabetes, or steatosis on any scan, or high aminotransferases [2]) should have noninvasive testing for fibrosis with FIB-4:
FIB-4:
• If a person has a FIB-4 index below 1.3, they can be considered at low risk for liver complications and followed by their primary provider.
• An index above 2.67 raises a red flag that calls for referral to a hepatologist.
• An index between 1.3 and 2.67 tells the practitioner to measure LSM by FibroScan.
FibroScan:
• An LSM below 8 kPa indicates low risk.
• An LSM above 12 kPa calls for referral to a hepatologist.
• An LSM from 8 to 12 kPa also calls for referral to a hepatologist for liver biopsy or MR elastography or monitoring with risk reevaluated in 2 to 3 years
See the AGA Clinical Care Pathway [2] for more details
To determine whether this algorithm can work in the general US adult population, researchers conducted this validation of the AGA Clinical Care Pathway in a nationally representative database-the 2017-2018 National Health and Nutrition Examination Survey (NHANES) data set-and looked for adults with valid FibroScan results and lab data that would allow them to calculate FIB-4 index. Focusing on people with type 2 diabetes, two or more metabolic risk factors, and elevated aspartate aminotransferase, and excluding heavy drinkers, they followed the FIB-4/FibroScan algorithm described just above.
Of the 4459 people with met those criteria, 3196 had low risk and no need for referral, 151 had high risk and needed to see a specialist, and the remaining 1112 had an indeterminate midrange result and needed FibroScan to determine LSM. Among 1021 people in the midrange group who had LSM values available, 838 had low risk (LSM below 8 kPa) and did not need specialist care, 115 had an indeterminate midrange LSM (8 to 12 kPa) that called for further evaluation by a hepatologist, and 68 had an LSM above 12 kPa that also warranted referral to a specialist.
The whole study group averaged 49.3 years in age, 48% were men, 10.4% were Hispanic, and body mass index averaged 31.9 kg/m2-in the obese range. Applying FIB-4 testing classified 73% of the group as low risk and thus spared them referral to a hepatologist or FibroScan evaluation. Among people who went on to get a FibroScan, that test classified another 19% of participants as low risk with no need for referral. All told, in this nationally representative group at risk for fibrotic NASH, the AGA Clinical Care Pathway decision tree [2] sent only 8% to a hepatologist, including only 11% of people with type 2 diabetes.
Comparing the low-risk group with the high-risk group, the researchers found high-risk people significantly older (average 66.43 vs 47.68, P < 0.001) but statistically similar by sex, body mass index, and race. Liver-relevant lab values-such as total bilirubin, aminotransferases, platelet count, and HbA1C-proved consistently significantly worse in the high-risk referred group.
The research team concluded that this simple algorithm can identify at-risk NAFLD patients who need specialist care and assure primary care providers (and insurers) that a big majority of people with NAFLD "can be managed by their treating physicians without the need for specialty care if screening guidelines are implemented."
References
1. Alkhouri N, Payne J, Phuc Le P, et al. Validation of the AGA Clinical Care Pathway to risk stratify patients with NAFLD and determine if hepatology referral is warranted at the United States population level. AASLD-The Liver Meeting, November 4-8, 2022, Washington, DC. Abstract 89.
2. Kanwal F, Shubrook JH, Adams LA, et al. Clinical Care Pathway for the risk stratification and management of patients with nonalcoholic fatty liver disease. Gastroenterology. 2021;161:1657-1669. doi: 10.1053/j.gastro.2021.07.049. https://www.gastrojournal.org/article/S0016-5085(21)03384-9/
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