The Silhouettes Fatigue Scale: a validity study with individuals with physical disabilities and chronic pain

Abstract

Purpose

Fatigue is known to interfere with function in individuals with physical disabilities. In order to monitor changes in fatigue over time and evaluate the efficacy of treatments, psychometrically sound measures of fatigue are needed. The aim of this work was to evaluate the validity of the Silhouettes Fatigue Scale with English instructions (SFS-EN) in a sample of adults with physical disabilities living in the USA.

Methods

Individuals with medical conditions associated with physical disabilities responded to an online survey that included the SFS-EN as well as another validated measure of fatigue (PROMIS short form-4a Fatigue Scale), and measures of pain intensity and pain catastrophizing.

Results

523 individuals participated (mean age = 59.1 years; SD = 11.4). Most participants were Caucasian (89%), women (59%) and unemployed (71%). Results showed strong positive correlations between both measures of fatigue, supporting the convergent validity of the SFS-EN. In addition, the magnitude of this association was significantly greater than the association between the scores of the SFS-EN and the measures of pain intensity and pain catastrophizing, supporting the former’s discriminant validity.

Conclusions

The findings extend previous results supporting the SFS as a brief, easy to administer and understand, and valid measure of fatigue.

IMPLICATIONS FOR REHABILITATION

• Fatigue is common in adults with physical disabilities and chronic pain.

• The Silhouettes Fatigue Scale (SFS) is a new single-item measure of general fatigue.

• Findings show that the SFS with English instructions (SFS-EN) is an easy to understand measure.

• Results support the convergent and discriminant validity of the SFS-EN score in adults with physical disabilities and chronic pain.

Keywords:

• Fatigue
• Silhouettes Fatigue Scale
• validity
• assessment
• chronic pain
• disabilities

Disclosure statement

The authors declare no financial or other relationships that might lead to a conflict of interest related to this study.

Additional information

Funding

JM’s work is supported by the Spanish Ministry of Economy, Industry and Competitiveness [RTI2018-09870-B-I00; RED2018-102546-T], the European Regional Development Fund (ERDF), the Government of Catalonia [AGAUR; 2017SGR-1321], Fundación Grünenthal (Spain), Universitat Rovira i Virgili (PFR program), and ICREA-Acadèmia. RV’s work is supported by the Spanish Ministry of Science and Innovation with a Ramón y Cajal contract [RYC2018-024722-I].