Younossi 2016: Global NAFLD Prevalence Meta-Analysis

Background

Dr. Zobair Younossi, Chair of the Global NASH Council, published this authoritative systematic review in Hepatology establishing the worldwide prevalence and disease burden of non-alcoholic fatty liver disease (NAFLD). This study provides the epidemiological context for why screening tools like the Fatty Liver Index are urgently needed.

Study Design

Methodology:

• •Systematic review and meta-analysis
• •Literature search: 1989-2015
• •86 studies included from 22 countries
• •Total sample: 8,515,431 individuals
• •Imaging or histology-based diagnosis required

Geographic Coverage:

• •North America: 24 studies
• •Europe: 21 studies
• •Asia: 32 studies
• •Middle East: 7 studies
• •South America: 2 studies

Key Epidemiological Findings

Global NAFLD Prevalence:

• •Overall: 25.24% (95% CI: 22.10-28.65%)
• •Approximately 1.8 billion people affected worldwide
• •Most common chronic liver disease globally

Regional Variation:

Region	Prevalence
Middle East	31.8%
South America	30.5%
Asia	27.4%
USA	24.1%
Europe	23.7%

Associated Metabolic Comorbidities: Among NAFLD patients:

• •Obesity: 51.3%
• •Type 2 diabetes: 22.5%
• •Hyperlipidemia: 69.2%
• •Metabolic syndrome: 42.5%
• •Hypertension: 39.3%

Disease Progression

NAFLD to NASH:

• •59.1% of biopsied NAFLD patients had NASH
• •NASH prevalence in general population: ~3-5%

Fibrosis Prevalence:

• •Any fibrosis in NASH: 41%
• •Advanced fibrosis (F3-F4): 7.0% of all NAFLD
• •Cirrhosis: 1.9% of NAFLD patients

Natural History:

• •Fibrosis progression: ~1 stage per 14 years in NAFLD, ~7 years in NASH
• •Annual HCC incidence in NASH cirrhosis: 5.3 per 1,000
• •All-cause mortality 15% higher in NAFLD vs. general population

Implications for Screening

The staggering prevalence statistics highlight the need for:

1. •Population-level screening: Cannot ultrasound 25% of adults
2. •Simple algorithms: FLI enables primary care screening
3. •Risk stratification: Identify which NAFLD patients need specialty referral
4. •Early intervention: Detect before progression to NASH and fibrosis

Economic Burden

Healthcare costs (US data extrapolation):

• •Direct medical costs: $103 billion annually
• •Lost productivity: $188 billion annually
• •Combined burden approaching $300 billion in US alone

Future projections:

• •NAFLD prevalence increasing with obesity epidemic
• •NASH expected to become leading cause of liver transplant by 2025
• •Economic burden projected to double by 2030

Clinical Recommendations

The authors emphasized:

1. •Primary care awareness: NAFLD is not rare — screen high-risk patients
2. •Metabolic syndrome screening: All metabolic syndrome patients should be evaluated
3. •Non-invasive tools: FLI and similar indices appropriate for initial screening
4. •Specialist referral: Patients with elevated FLI need further evaluation

Metabolic Health Perspective

The Younossi meta-analysis provides compelling rationale for metabolic health screening:

The Hidden Epidemic:

• •1 in 4 adults has fatty liver
• •Majority are undiagnosed
• •Most have concurrent metabolic dysfunction

Why Screening Matters:

• •NAFLD precedes overt diabetes by years
• •Reversible with lifestyle intervention when detected early
• •Progression to NASH/fibrosis preventable

Role of FLI:

• •Cost-effective screening at population level
• •Identifies metabolically unhealthy individuals
• •Enables early intervention before irreversible damage
• •Trackable metric for lifestyle modification success

For metabolic health optimization, understanding that fatty liver affects 25% of adults underscores the importance of proactive screening. FLI provides a practical tool to identify those who harbor this "silent" metabolic dysfunction that drives diabetes, cardiovascular disease, and liver-related mortality.