Psychometric analysis of the Neuro-QoL Fatigue in generalized Myasthenia Gravis (gMG) using data from a phase 3 trial

Area of Science:

• Neurology
• Clinical Psychology
• Health Outcomes Research

Background:

• Fatigue is a significant symptom impacting quality of life for adults with generalized Myasthenia Gravis (gMG).
• Accurate and reliable measurement of fatigue is crucial for evaluating treatment efficacy in gMG.

Purpose of the Study:

• To evaluate the psychometric properties of the Neuro-QoL Fatigue measure, including its 19-item and short-form versions.
• To determine the suitability of the Neuro-QoL Fatigue measure for assessing fatigue in adults with gMG.

Main Methods:

• Analysis of data from the Vivacity-MG3 phase 3 clinical trial (NCT04951622) involving 196 participants with gMG.
• Application of factor analytic and classical test theory (CTT) methods to assess reliability, validity, and sensitivity to change.
• Investigation of thresholds for meaningful within-person improvement in fatigue scores.

Main Results:

• Factor analysis supported a unidimensional model for the Neuro-QoL Fatigue scores.
• High internal consistency (alpha=0.95) and test-retest reliability (r=0.92) were demonstrated for the full form.
• Both versions showed expected correlations with reference variables, differentiated distinct clinical groups, and detected changes over time, with meaningful improvement thresholds identified.

Conclusions:

• The Neuro-QoL Fatigue measure exhibits robust psychometric properties for use in adults with gMG.
• Evidence supports the reliability and validity of both the 19-item and short-form versions.
• The findings validate the Neuro-QoL Fatigue measure as a suitable tool for gMG research and clinical practice.