Fatigue and energy scales don't necessarily measure same thing [in HIV] (Lerdal et al, 2012)

[Dolphin]

As fatigue tends to be measured in ME/CFS research, I found this of interest:

"Fatigue and energy measures were moderately correlated with each other in the morning but not in the evening. The concepts of energy and fatigue were inversely related, but not polar opposites in this sample. Fatigue and energy may therefore be distinct constructs that should not be used interchangeably, either in measurement or when interpreting outcomes for research or clinical purposes."

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http://www.psy-journal.com/article/S0165-1781(12)00463-5/abstract

Psychiatry Research

Article in Press

Lee Fatigue and Energy Scales: Exploring aspects of validity in a sample of women with HIV using an application of a Rasch model

Anners Lerdal, Anders Kottorp, Caryl L. Gay, Kathryn A. Lee


Received 24 January 2012; received in revised form 12 July 2012; accepted 26 August 2012. published online 17 September 2012.

Abstract*

This study examines the psychometric properties of the Lee Fatigue and Energy Scales (visual analog version) using a Rasch model application.

The relationship between fatigue and energy is also described for a convenience sample of 102 women with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) who completed the Lee Fatigue and Energy Scales in the morning and evening.

Both scales were assessed for internal scale validity, unidimensionality, and uniform differential item functioning in relation to morning and evening ratings.

Analyses confirmed that both the Fatigue and Energy Scales demonstrated evidence of internal scale validity and unidimensionality.

Mean fatigue measures were also higher in the evening than in the morning and mean energy measures were higher in the morning than in the evening (both p<0.001), indicating that time of day is an important consideration.

Fatigue and energy measures were moderately correlated with each other in the morning but not in the evening.

The concepts of energy and fatigue were inversely related, but not polar opposites in this sample.

Fatigue and energy may therefore be distinct constructs that should not be used interchangeably, either in measurement or when interpreting outcomes for research or clinical purposes.

Keywords: Psychometrics, Measurement, Quality of life, Symptoms, Rasch analysis

* I gave each sentence its own paragraph

 

[Esther12]

I'm too tried to thikn this through properly, but it does seem interesting.

 

[taniaaust1]

thanks for posting this .

I myself find fatigue and energy levels to often be two completely different things.. eg I can be extremely tired or fatigued but still feel energetic.