Quality of Life Research

, Volume 20, Issue 9, pp 1447–1456

A 7-item version of the fatigue severity scale has better psychometric properties among HIV-infected adults: an application of a Rasch model

  • Anners Lerdal
  • Anders Kottorp
  • Caryl Gay
  • Bradley E. Aouizerat
  • Carmen J. Portillo
  • Kathryn A. Lee
Article

DOI: 10.1007/s11136-011-9877-8

Cite this article as:
Lerdal, A., Kottorp, A., Gay, C. et al. Qual Life Res (2011) 20: 1447. doi:10.1007/s11136-011-9877-8

Abstract

Purpose

To examine the psychometric properties of the 9-item Fatigue Severity Scale (FSS) using a Rasch model application.

Methods

A convenience sample of HIV-infected adults was recruited, and a subset of the sample was assessed at 6-month intervals for 2 years. Socio-demographic, clinical, and symptom data were collected by self-report questionnaires. CD4 T-cell count and viral load measures were obtained from medical records. The Rasch analysis included 316 participants with 698 valid questionnaires.

Results

FSS item 2 did not advanced monotonically, and items 1 and 2 did not show acceptable goodness-of-fit to the Rasch model. A reduced FSS 7-item version demonstrated acceptable goodness-of-fit and explained 61.2% of the total variance in the scale. In the FSS-7 item version, no uniform Differential Item Functioning was found in relation to time of evaluation or to any of the socio-demographic or clinical variables.

Conclusion

This study demonstrated that the FSS-7 has better psychometric properties than the FSS-9 in this HIV sample and that responses to the different items are comparable over time and unrelated to socio-demographic and clinical variables.

Keywords

FatigueHIVPsychometricsSymptomsQuality of life

Abbreviations

AIDS

Acquired immune deficiency syndrome

BMI

Body mass index

DIF

Differential item functioning

DS

Daytime sleepiness subscale

FSS

Fatigue severity scale

GSDS

General sleep disturbance scale

HIV

Human immunodeficiency virus

PCA

Principal component analysis

SE

Standard error

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Anners Lerdal
    • 1
  • Anders Kottorp
    • 2
  • Caryl Gay
    • 3
  • Bradley E. Aouizerat
    • 4
  • Carmen J. Portillo
    • 5
  • Kathryn A. Lee
    • 3
  1. 1.Lovisenberg Deaconal University CollegeOsloNorway
  2. 2.Division of Occupational Therapy, Department of Neurobiology, Care Sciences and SocietyKarolinska InstitutetStockholmSweden
  3. 3.Department of Family Health Care NursingUniversity of California, San FranciscoSan FranciscoUSA
  4. 4.Department of Physiological Nursing and Institute for Human GeneticsUniversity of California, San FranciscoSan FranciscoUSA
  5. 5.Community Health SystemsUniversity of California, San FranciscoSan FranciscoUSA