What are the diagnostic criteria for acute‑on‑chronic liver failure?

Diagnostic Criteria for Acute-on-Chronic Liver Failure

The diagnosis of ACLF requires three essential components: (1) acute onset with rapid clinical deterioration, (2) liver failure defined by elevated bilirubin AND elevated INR in patients with chronic liver disease with or without cirrhosis, and (3) at least one extrahepatic organ failure (neurologic, circulatory, respiratory, or renal). 1

Core Diagnostic Framework

The 2024 AASLD Practice Guidance establishes minimum critical components that must ALL be present for ACLF diagnosis 1:

1. Acute Onset with Rapid Deterioration

• The clinical condition must deteriorate rapidly, though the exact timeframe remains somewhat undefined in the literature
• This represents a distinct phase beyond typical decompensated cirrhosis

2. Liver Failure Parameters

• Elevated bilirubin: While optimal cutoffs remain debated, values of 5-12 mg/dL have been examined across different definitions 1
• Elevated INR: Coagulopathy defined as INR ≥1.5-2.5 has been used to define liver failure 1
• Both parameters must be present in the context of chronic liver disease (with or without established cirrhosis)

3. Extrahepatic Organ Failure

At least one of the following organ systems must be failing 1:

• Neurologic (hepatic encephalopathy)
• Circulatory (shock, vasopressor requirement)
• Respiratory (hypoxemia, mechanical ventilation need)
• Renal (acute kidney injury, dialysis requirement)

Important Context: Multiple Competing Definitions

A critical pitfall is that three major regional definitions exist, creating diagnostic confusion 1:

Regional Definition Differences

• APASL (Asian Pacific): Recognizes patients at an early stage; highly sensitive but less specific, as most patients will not die by Day 28 1

• EASL-CLIF (European): Includes patients at intermediate stages (ACLF-1, ACLF-2) and late stage (ACLF-3); grades based on number and type of organ failures 1, 2

• NACSELD (North American): Includes only patients at often preterminal stage with ≥2 extrahepatic organ failures 1

These definitions likely characterize different stages of the same disease continuum 1. The AASLD guidance focuses on patients fulfilling NACSELD criteria and selected patients with advanced APASL or EASL-CLIF criteria, as these represent the most severe forms requiring ICU management 1.

Prognostic Grading

Once ACLF is diagnosed, severity stratification is critical:

• 28-day mortality ranges from 30-50% depending on definition and geography 1
• Mortality correlates directly with number of organ failures 1
• MELD and MELD-Na scores underestimate mortality in ACLF because they don't capture extrahepatic organ failures 1

ACLF-Specific Scoring Systems

Three validated scores outperform traditional liver scores 1:

• NACSELD ACLF score: Includes extrahepatic organ failure, age, MELD, WBC, albumin
• CLIF-C ACLF score: Includes hepatic and extrahepatic failures, age, WBC
• AARC score: Includes bilirubin, creatinine, lactate, INR, hepatic encephalopathy

Common Precipitants to Identify

The acute insult may be 1:

• Liver-related: Alcohol-associated hepatitis, viral hepatitis flare, drug-induced liver injury
• Non-liver-related: Bacterial infections (most common), GI bleeding, surgery
• Often unidentified: No clear precipitant found in many cases

Key Clinical Caveat

The EASL-CLIF definition characterizes ACLF as having a 28-day mortality ≥20% (versus ≤5% in decompensated cirrhosis without ACLF) 2. This high mortality threshold distinguishes ACLF from simple acute decompensation and mandates aggressive ICU-level management with early transplant evaluation in appropriate candidates.