Beyond 'Nonalcoholic' and 'Fatty': The Evolution of NAFLD Terminology

The medical field is constantly evolving, and so is the terminology used to describe various conditions and diseases. Establishing more precise naming conventions enhances the clinical vernacular. The ensuing clarity can help practitioners gain a better understanding of the condition itself and improve diagnosis, treatment and overall patient care.

Have you ever wondered why the terms "nonalcoholic" and "fatty" are used to describe a liver disease that affects millions of people worldwide? Well, the terminology surrounding nonalcoholic fatty liver disease (NAFLD) is changing — and for good reason.

The term "nonalcoholic steatohepatitis" was coined in 1980 to describe liver disease associated with being overweight or obese, but it does not accurately capture the disease's etiology, histological features and can be stigmatizing. “Fatty”. Individuals at risk for NAFLD who consume alcohol above nonalcoholic thresholds are excluded from the current terminology even though there are shared pathophysiological pathways. Also, various scoring systems are used to categorize the severity of steatosis, disease activity and fibrosis. Given the complexity of the condition, it had become clear to researchers and clinicians that the current terminology did not meet the need for accurately describing the metabolic dysfunction.

An article published recently in the Journal of Hepatology described a consensus statement about adopting new terminology for this liver disease. The growing dissatisfaction with the existing nomenclature and diagnostic criteria for NAFLD prompted the American Association for the Study of Liver Diseases (AASLD), European Association for the Study of the Liver (EASL) and many healthcare experts from the world of hepatology to push for a change.

The experts advocated for a more accurate and comprehensive terminology to reflect the various subtypes and severity of the disease, adding that it was crucial to move beyond the simplistic labels of "nonalcoholic" and "fatty." Doing so, they argued, can improve diagnosis, treatment and public awareness of this significant health issue.

The multisociety study utilized a Delphi process, which involves multiple rounds of surveys and discussions with a diverse panel of experts, practitioners, and patient advocates. The goal was to develop a unified global approach to naming and defining these liver diseases to improve disease awareness, policy change, and access to care.

After tabulating all respondents and surveys, it was decided that steatotic liver disease (SLD) should be the umbrella term for the multiple causes of steatosis, the medical term for the accumulation of too much fat in liver cells. A significant majority of those who participated agreed to relabel NAFLD as metabolic dysfunction-associated steatotic liver disease (MASLD), which includes the presence of hepatic steatosis and a cardiometabolic risk factor. To accurately define those patients who consume higher than normal amounts of alcohol, MetALD was chosen.This term highlights the metabolic overlap that is shared among patients of varying alcohol status and maintains continuity with MASLD as opposed to alcohol-related liver disease (ALD). The inflammation and cellular injury that is associated with NASH is now known as metabolic-associated steatohepatitis, which has the catchy acronym MASH.

The consensus statement provided valuable insights into the current challenges and dissatisfaction with the nomenclature and disease definition for fatty liver diseases. The proposed modifications and new nomenclature have the potential to improve disease awareness, policy change and access to care for individuals affected by these liver diseases. It is the authors’ hope that this policy change will hasten drug and biomarker development so that these patients can receive optimal treatment.