NAFLD is a worldwide clinical problem. In the United States, we estimate that 1 of 3 people are affected, but rates vary globally. Additionally, a genetic component has been implicated in the development of the disease. For example, differences in the severity and progression of NAFLD that occur between individual patients and between patients of various ethnicities suggest the involvement of genetic factors, and NAFLD has been associated with variants in genes such as PNPLA3 and TM6SF2.

In addition to its global prevalence, NAFLD is a multisystem disease. Insulin resistance is a central feature in its development, along with systemic abnormalities such as type 2 diabetes, hypertension, and hyperlipidemia. Of course, weight gain and obesity are key factors in the development of NAFLD, and obesity is also common in patients with nonalcoholic steatohepatitis (NASH). In fact, Younossi reported at The Liver Meeting that approximately 80% of the population with NASH has obesity (abstract LO4). In addition to cardiovascular disease and stroke, obesity-associated comorbidities such as sleep apnea and, potentially, chronic kidney disease are therefore also very relevant. Only a minority of patients with NAFLD will go on to develop NASH, but in those who do, progression to stage 2 and especially stages 3 and 4 fibrosis (stage 4 is cirrhosis) is associated with higher rates of complications of liver disease, hepatocellular carcinoma, and all-cause mortality. 

Given the need for multidisciplinary care in NAFLD, it is critical that we partner with our colleagues. If we do not, especially at the level of primary care, we are not going to have the ability to identify patients at a stage that is treatable. Moreover, patients with NASH are often asymptomatic, and when they do present for medical attention, they may encounter different silos in the medical system, with varying approaches by specialty.

We presented a poster abstract at The Liver Meeting 2021 on current challenges faced by hepatologists and endocrinologists in caring for patients with NASH (abstract 649); we found that 48% of hepatologists and 23% of endocrinologists reported suboptimal skills in managing cardiovascular risk. In addition, more endocrinologists than hepatologists reported suboptimal knowledge in determining follow-up frequency, and endocrinologists reported suboptimal skills in quantifying fibrosis (78%) and in estimating hepatocellular carcinoma risk (74%). These are important findings that relate to the ability to identify patients who should receive screening, further referral, or treatment.

Our understanding of NAFLD has been developing rather rapidly, and, as such, the story of the 5 blind men and the elephant comes to mind regarding the roles of different practitioners. The cardiologist is focused on the trunk because that is where the coronary arteries are, as well as on lipoproteins, possibly the subfractionation of the lipoprotein particles, and the blood pressure. The endocrinologist is focused on hemoglobin A_1c and perhaps on weight. The hepatologist or gastroenterologist is looking at the liver enzymes and is focused on the liver. It is important, however, that we are all thinking about NAFLD, whether it is the cardiologist who is seeing a patient initially when liver disease may not be apparent, the endocrinologist who is focused on the hemoglobin A_1c and may incidentally notice an echogenic liver on ultrasound, or the primary care doctor whose patient with obesity has mildly elevated liver enzymes that might be attributable to statin use.

We currently have interventions that work, and more will be emerging in the future. Weight loss can reverse fibrosis in NASH. Contemporary practice guidelines state that a 5% to 10% weight loss through lifestyle changes or bariatric surgery is the treatment of choice to prevent NAFLD progression in patients with obesity. Having a dedicated weight intervention pathway may be particularly effective (abstract 29). Moreover, among individuals with obesity who have already developed NASH, bariatric surgery has been linked to a significantly lower risk of incident major adverse liver outcomes and major adverse cardiovascular events.  

Similarly, diabetes control is needed to not only reduce hemoglobin A_1c but also to manage NASH associated with diabetes. Glucagon-like peptide-1 analogues are now approved by the US Food and Drug Administration for weight loss, in addition to diabetes, and these agents have some of the highest rates of NASH resolution associated with treatment that we have with any pharmacotherapy currently being developed for NASH. Whether these agents will reverse fibrosis or halt progression to cirrhosis remains to be determined, but it is quite clear that pharmacologic approaches to managing diabetes could have other effects in terms of NASH and FLD.

In conclusion, each practitioner should think of NAFLD not in isolation, but as being integral to the metabolic syndrome, understanding that patients with more advanced forms of the disease also have a higher risk of morbidity and mortality. Identifying those individuals who are at greater risk or who already have advanced fibrosis should be something that we all incorporate as part of our assessment.