What are some standardized fatigue scales?

Standardized Fatigue Scales for Clinical Assessment

The most validated and widely used standardized fatigue scales include the Brief Fatigue Inventory (BFI), Fatigue Severity Scale (FSS), and Functional Assessment of Cancer Therapy-Fatigue (FACT-F), which provide reliable quantification of fatigue severity and impact on daily functioning. 1, 2

Unidimensional Fatigue Scales

These scales primarily measure fatigue severity:

• Numeric Rating Scale (0-10): Simple screening tool recommended by NCCN guidelines

  • 0-3: Mild fatigue
  • 4-6: Moderate fatigue
  • 7-10: Severe fatigue (associated with marked decrease in physical functioning) 1, 2

• Fatigue Severity Scale (FSS):

  • 9-item questionnaire with excellent internal consistency (Cronbach alpha = 0.93)
  • Validated across multiple conditions including multiple sclerosis, stroke, and sleep disorders
  • Mean score ≥4 indicates substantial fatigue
  • FSS-7 (7-item version) shows improved psychometric properties 3, 4

• Functional Assessment of Cancer Therapy-Fatigue (FACT-F):

  • 13-item standalone questionnaire from the FACIT series
  • Validated in mixed cancer populations
  • Measures severity dimension 1

• European Organisation for Research and Treatment of Cancer Quality-of-Life Questionnaire (EORTC QLQ-C30):

  • 30-item quality-of-life questionnaire with 3-item fatigue subscale
  • Brief and easy to use, though psychometric properties are weaker than more extensive scales
  • Validated in lung cancer, bone marrow transplantation, and metastatic cancer 1

• Profile of Mood States-Fatigue (POMS-F):

  • 65-item questionnaire with 7-item fatigue subscale
  • Assessed in both cancer and non-cancer populations
  • Has defined minimum clinically significant difference 1

Multidimensional Fatigue Scales

These scales measure multiple aspects of fatigue:

• Brief Fatigue Inventory (BFI):

  • 9-item numeric scale validated in mixed cancer populations
  • Measures both severity and interference dimensions
  • Has cutoff scores for mild, medium, and severe fatigue 1, 2

• Piper Fatigue Scale (PFS):

  • 22-item self-report scale measuring 4 dimensions of fatigue:
    • Behavioral/severity (6 items)
    • Sensory (5 items)
    • Cognitive/mood (6 items)
    • Affective meaning (5 items)
  • Strong internal consistency (Cronbach's α = 0.89-0.97)
  • Validated in cancer patients and survivors 1

• Fatigue Symptom Inventory (FSI):

  • 13-item scale validated in breast cancer and mixed cancer populations
  • Measures severity, duration, and interference dimensions 1

• Multidimensional Fatigue Inventory (MFI-20):

  • 20-item scale designed for cancer patients
  • Measures general fatigue, physical fatigue, mental fatigue, reduced motivation, and reduced activity 1

• Multidimensional Fatigue Symptom Inventory (MFSI-30):

  • 30-item scale validated in breast cancer and mixed cancer populations
  • Measures general fatigue, physical fatigue, emotional fatigue, mental fatigue, and vigor
  • Shows favorable psychometric properties 1, 5

• Modified Fatigue Impact Scale (MFIS):

  • Measures physical, cognitive, and psychosocial dimensions of fatigue
  • Provides more comprehensive assessment than unidimensional scales
  • Shows acceptable reliability (ICC=0.863) over six months 6, 5

• Fatigue Descriptive Scale (FDS):

  • Evaluates severity, quality, and periodicity of fatigue
  • Highly correlated with FSS (r = 0.87)
  • Particularly useful in multiple sclerosis patients 7

Selection Considerations

When selecting a fatigue scale, consider:

1. Purpose of assessment: Screening vs. comprehensive evaluation
2. Patient population: Some scales are validated for specific conditions
3. Dimensions of interest: Physical, cognitive, emotional aspects of fatigue
4. Administration time: Brief scales for routine clinical use vs. comprehensive scales for research
5. Psychometric properties: Reliability, validity, and sensitivity to change

Clinical Application

For routine clinical screening:

• Use the 0-10 numeric rating scale as an initial screening tool
• For scores ≥4, proceed with more comprehensive assessment using validated scales

For comprehensive assessment:

• Use multidimensional scales like BFI, PFS, or MFIS to capture different aspects of fatigue
• Consider disease-specific validated scales when available

Important Caveats

• Different scales may emphasize different aspects of fatigue (physical vs. cognitive)
• Direct comparison of raw scores across different patient populations may not be valid
• Depression often correlates with fatigue and should be assessed concurrently 5
• Laboratory evaluation should accompany fatigue assessment to identify treatable causes 2

By selecting appropriate standardized fatigue scales, clinicians can better quantify fatigue severity, understand its impact on patients' lives, and monitor response to interventions.