What is the concordance between Psychometric Hepatic Encephalopathy Score (PHES) and Flicker tests in the diagnosis of minimal hepatic encephalopathy in cirrhotic patients?

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Concordance Between PHES and Flicker Tests in Minimal Hepatic Encephalopathy Diagnosis

The concordance between PHES (Psychometric Hepatic Encephalopathy Score) and Critical Flicker Frequency (CFF) tests is poor, with diagnostic agreement values of only 47-54% for minimal hepatic encephalopathy (MHE), meaning these tests cannot be used interchangeably and often identify different patient populations. 1

Evidence of Poor Concordance

The most definitive evidence comes from a 2014 study that directly compared these diagnostic tools:

  • In patients evaluated with conventional PHES, the diagnostic agreement between CFF and PHES was only 54% 1
  • When modified PHES was used, concordance dropped further to 47% 1
  • CFF and PHES identified minimal HE with markedly different sensitivities: CFF showed 22% sensitivity with 100% specificity, while conventional PHES showed 30% sensitivity with 89% specificity in the same patient population 1

A more recent 2024 prospective study reinforced these findings:

  • All test results correlated significantly with each other (p<0.05), except for CFF, which showed no significant correlation with other diagnostic tools 2
  • The study concluded that minimal HE tests cannot be equated with one another and have limited interchangeability 2

Why Concordance is Low

These tests measure fundamentally different aspects of brain dysfunction:

  • PHES evaluates multiple cognitive domains through paper-pencil tests including attention and psychomotor performance, scored against population-specific normograms 3
  • CFF assesses degree of vigilance through measurement of visual perception thresholds, representing a single neurophysiological parameter 3
  • CFF results are influenced by equipment-dependent variables including luminance and color of transmitted light, with thresholds varying between centers 3

Clinical Implications

For multicenter studies or research, guidelines recommend using at least two validated testing strategies including both paper-pencil tests (PHES) and computerized tests (CFF) or neurophysiological tests, precisely because of their poor concordance 4

The lack of concordance means:

  • A patient may test positive on PHES but negative on CFF, or vice versa 1
  • Neither test alone provides comprehensive assessment of minimal hepatic encephalopathy 3, 4
  • The choice of diagnostic tool significantly impacts which patients receive an MHE diagnosis 2, 1

Diagnostic Performance Comparison

For detecting minimal HE specifically:

  • CFF shows very low sensitivity (22-37%) but high specificity (94-100%) 1
  • Conventional PHES shows similarly low sensitivity (30%) with 89% specificity 1
  • Modified PHES demonstrates slightly better sensitivity (49%) but lower specificity (74%) 1

However, for overt hepatic encephalopathy, CFF performs excellently with 97-98% sensitivity and 94-100% specificity 1, while conventional PHES shows only 73% sensitivity and 89% specificity 1

Important Caveats

The diagnosis of minimal HE should be made based on adjusted norm values for the tests exclusively, as percentage of abnormal results changes significantly when adjusted norms are used versus fixed cutoffs 2. For example, abnormal Stroop results changed from 79.8% to 52.3% when adjusted norms were applied 2.

CFF results require age-matched and population-specific reference data due to influence of variables like age and gender 3, 5. Similarly, PHES normograms show important differences among German, Italian, and Spanish populations 3.

References

3
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

4
Guideline

Diagnosing Hepatic Encephalopathy

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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