Validation of the Lifeware Fatigue Instrument in Multiple Sclerosis Patients

Background: Fatigue is one of the most common and debilitating symptoms in multiple sclerosis (MS). While various instruments have been developed to examine fatigue, it is of importance for clinicians to have quick, valid and reliable methods of assessing fatigue in people with MS (PwMS). The LIFEware^TM system is a short, patient-reported outcomes (PRO) questionnaire assessing physical and psychosocial limitations that includes a single-item fatigue measurement which has not been validated to date.

Objectives: This validation study aimed to investigate the utility of the single-item measure of LIFEware^TM fatigue in PwMS.

Methods: MS patients were extracted from the prospective Cardiovascular, Environmental and Genetic (CEG) study. The LIFEware™ fatigue measurement was completed by 101 MS patients who simultaneously completed the validated Fatigue Severity Scale (FSS). Criterion validity was assessed using correlation analysis between LIFEware™ fatigue and the FSS. Correlations with the Expanded Disability Status Scale (EDSS) and depression as measured by Beck’s Depression Inventory (BDI) were used to measure convergent validity, while body mass index (BMI), age, and disease duration were correlated to measure divergent validity. Receiver Operating Characteristic curve (ROC) analysis was carried out to determine an optimal cutoff that can distinguish fatigued individuals from non-fatigued individuals.

Results: LIFEware™ fatigue correlated strongly with the FSS (r=0.63, p <.001), indicating good criterion validity. Construct validity was supported by correlations between LIFEware™ fatigue and EDSS (r=0.39, p<.001) and BDI (r=0.38, p<.001), and by the weak correlations with BMI (r=-0.13), age (r=0.18), and disease duration (r=0.10, all p>.05). 

Conclusions: The validity of LIFEware™ fatigue suggests that it could be useful as a quick screening tool for assessing fatigue in PwMS.