Lean Steatotic Liver Disease Affects 12% of US Adults, Study Finds

Donghee Kim, MD, PhD

Credit: Stanford Medicine

New research is providing insight into the prevalence of lean steatotic liver disease (SLD) in the US, addressing potential changes in previous estimates following a 2023 change in liver disease nomenclature.¹

Leveraging National Health and Nutrition Examination Survey (NHANES) data from 2017-2023, investigators determined the age-adjusted prevalence of lean SLD to be 12.8%, including a 9.3% prevalence of lean metabolic dysfunction-associated steatotic liver disease (MASLD), a 1.3% prevalence of metabolic dysfunction and alcohol-related steatotic liver disease (MetALD), and a 1.0% prevalence of alcohol-related liver disease (ALD).¹

“A recent change in nomenclature from NAFLD to MASLD may have influenced the current estimates of lean MASLD, as some individuals categorized as lean NAFLD may no longer meet the criteria for lean MASLD,” Donghee Kim, MD, PhD, a social science research scholar in medicine at Stanford University School of Medicine, and colleagues wrote.¹

In June 2023, a multistakeholder effort led by the American Association for the Study of Liver Diseases, the European Association for the Study of the Liver, and the Asociación Latinoamericana para el Estudio del Hígado yielded new liver disease nomenclature to address concerns about the inaccurate and stigmatizing nature of the previous nomenclature. With the shift from NAFLD to MASLD, new diagnostic criteria were also introduced, which could pose significant implications for the validity of previous work exploring the prevalence of lean SLD based on outdated disease definitions.²

To provide an updated estimate of the prevalence of lean SLD and its subcategories, investigators examined NHANES 2017-2023 data for adults ≥ 18 years of age with a body mass index < 23 kg/m2 for non-Hispanic Asians and < 25 kg/m2 for all other races/ethnicities.¹

SLD was defined as controlled attenuation parameter (CAP) scores ≥ 263 dB/m, representing a sensitivity of 90%, with a more stringent cut-off of 285 dB/m used to optimize both sensitivity and specificity. Individuals who met the criteria for SLD were categorized into 3 groups:

• MASLD: SLD with cardiometabolic criteria and no other discernible cause
• MetALD: SLD with cardiometabolic criteria and consumed 140–350 g/week (women) and 210–420 g/week (men)
• ALD: SLD and either high alcohol consumption > 350 g/week (women)/> 420 g/week (men) plus cardiometabolic criteria or alcohol consumption > 140 g/week (women)/> 210 g/week (men) without cardiometabolic criteria

Among individuals with MASLD, investigators assessed transient elastography values and defined significant fibrosis as ≥ 8 kPa, advanced fibrosis as ≥ 11.6 kPa, and cirrhosis as ≥ 13.1 kPa.¹

Age-adjusted prevalence estimates for the entire US population were calculated using direct standardization, with age proportions based on the 2020 US Census population.¹

In total, the study included 2965 lean US adults. Based on this NHANES population, investigators found the weighted age-adjusted prevalence of SLD at a cut-off of 263 dB/m was 12.8% (95% CI, 10.4–15.2), representing approximately 5.9 million of the estimated 52.3 million lean US adults (mean age, 43.7 years; 43.6% male). The prevalence of MASLD was 9.3% (95% CI, 7.0–11.6, 4.2 million); MetALD was 1.3% (95% CI, 0.7–2.0, 0.6 million); and ALD was 1.0% (95% CI, 0.5–1.5, 0.5 million).¹

Investigators noted MASLD prevalence varied by race/ethnicity and was highest among non-Hispanic Asian individuals (16.7%; 95% CI, 11.6–21.9) followed by Hispanics (12.1%; 95% CI, 8.4–15.9), non-Hispanic Whites (8.9%; 95% CI, 6.2–11.6) and non-Hispanic Blacks (5.2%; 95% CI, 1.9–8.5). They additionally pointed out MetALD prevalence was greatest in non-Hispanic whites (1.6%, 95% CI: 0.6–2.5) compared to other racial/ethnic groups.¹

Within the MASLD group, the age-adjusted prevalence of significant fibrosis, advanced fibrosis, and cirrhosis was 5.6% (95% CI, 3.3–9.4), 2.4% (95% CI, 1.1–5.3) and 2.0% (95% CI, 0.8–4.7), respectively.¹

Investigators outlined multiple limitations to these findings, including the lack of histological data or imaging information available in the NHANES dataset; the absence of universally accepted cut-off guidelines for CAP scores and liver stiffness measurements; and potential bias from self-reported alcohol consumption.¹

“This study provides the most up-to-date prevalence rates for lean SLD and its subcategories, revealing that SLD affects one-tenth of lean American adults,” investigators concluded.¹

References

1. ^{Kim D, Danpanichkul P, Wijarnpreecha K, et al. Current Burden of Lean Metabolic Dysfunction-Associated Steatotic Liver Disease Among US Adults, 2017–2023. Alimentary Pharmacology and Therapeutics. https://doi.org/10.1111/apt.18501}
2. ^{Brooks A. From NAFLD to MASLD: 2023 Brings New Liver Disease Nomenclature. HCPLive. December 13, 2023. Accessed January 15, 2025. https://www.hcplive.com/view/from-nafld-to-masld-2023-new-liver-disease-nomenclature}