One word was the problem: “nonalcoholic.” For years the leading cause of chronic liver trouble worldwide carried a name that said what it was not, and in June 2023 the world’s main liver societies finally retired it.
Under the new scheme, nonalcoholic fatty liver disease (NAFLD) becomes metabolic dysfunction-associated steatotic liver disease, or MASLD. Nonalcoholic steatohepatitis (NASH) becomes MASH. AASLD, one of the lead societies behind the change, says MASLD affects more than 30% of the global population, which makes the naming fight far from academic.
An umbrella with several rooms
The framework puts steatotic liver disease (SLD) on top as the overarching term for fat buildup in the liver, whatever the cause. Beneath it sit distinct categories. MASLD covers people with hepatic steatosis who also show a cardiometabolic risk factor; the AASLD list has five to choose from, and one is enough. A patient with none of those factors and no known cause is classed as cryptogenic SLD.
The most consequential addition is MetALD, a category for people with MASLD who drink more alcohol than the MASLD limit allows. AASLD sets the bar at 140 g/week for females and 210 g/week for males. In the interview published by Gastroenterology & Hepatology, Dr. Mary Rinella put the same boundary in daily terms: a daily intake above 20 g for females and 30 g for males, yet below 50 g and 60 g respectively. Beyond that ceiling the diagnosis becomes alcohol-related liver disease, which also sits under the SLD umbrella.
Drug-induced liver injury and several rarer causes of steatosis get their own slots too.
Why the old names had to go
Rinella, who worked on the project for AASLD, laid out the case plainly. NAFLD and NASH were diagnoses of exclusion: a doctor had to rule out every other disease before using them. Some patients also found “fatty” and “nonalcoholic” stigmatizing, and “nonalcoholic” says nothing about what actually drives the disease.
The trigger was a rival label. A 2020 paper proposed MAFLD, short for metabolic dysfunction-associated fatty liver, with tighter metabolic criteria and a looser stance on drinking. Rinella warned that adopting it would have disturbed biomarker work and muddied the natural-history data built on decades of observation, at a moment when, as she put it, a therapy is almost within reach.
So the societies chose a different route. AASLD and its European counterpart, EASL, ran a Delphi consensus process, with Rinella and Professor Philip N. Newsome (for EASL) leading a steering committee with members from Europe, Asia, Africa and Latin America. In all, 224 people from 56 countries took part, over four voting rounds across 2.5 years. Around 2700 comments shaped the later statements. AASLD reports an 89% final response rate, with 85% of those responding approving the recommendation.
What stays the same
The panel was not unanimous in spirit. One camp wanted MAFLD; another wanted NAFLD left alone. Even the word “metabolic” drew argument, mainly from endocrinologists and pediatric specialists, because it is hard to define. A supermajority kept it anyway, since it tells people something about the root problem.
On steatohepatitis there was almost no dispute. In most voting iterations, 95% of respondents agreed the concept should stay central to understanding the disease, building biomarkers and assessing clinical trials.
AASLD stresses that the change is about language, not biology. The society says the new umbrella term leaves the disease’s course, trial design and biomarkers untouched, and the staging and severity measures used today remain in place. MetALD, however, is a group nobody has studied properly. The panel expects those patients to benefit from inclusion in trials and care pathways.
Several papers have already applied the new definitions to datasets such as the National Health and Nutrition Examination Survey, Rinella said in the November 2023 interview.
Sources
- New MASLD Nomenclature | AASLD
- Examining the Nomenclature Change From NAFLD and NASH to MASLD and MASH
