Usefulness of the MFIS-K, FSS, and FACIT-F Fatigue Scales in Korean Patients With MS, NMOSD, and MOGAD.

Background and purpose: Fatigue is common in demyelinating disorders of the central nervous system (CNS), including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). We aimed to validate the usefulness of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) and the Fatigue Severity Scale (FSS) relative to the Korean version of the Modified Fatigue Impact Scale (MFIS-K) in Korean patients with MS, NMOSD, and MOGAD.

Methods: There were 294 patients with MS (n=120), NMOSD (n=103), or MOGAD (n=71) enrolled in a prospective demyelinating CNS registry. Fatigue was measured using the FACIT-F, MFIS-K, and FSS. Sleep quality, quality of life, depression, and pain were evaluated using the Pittsburgh Sleep Quality Index (PSQI), 36-item Short-Form Survey (SF-36), and Beck Depression Inventory-II (BDI-II).

Results: The MFIS-K, FACIT-F, and FSS scores showed high internal consistencies and strong correlations with each other in the MS, NMOSD, and MOGAD groups. The scores on all three fatigue scales were correlated with PSQI, SF-36, and BDI-II results in the three groups. The areas under the receiver operating characteristic curves for the FSS and FACIT-F were 0.834 and 0.835, respectively, for MS, 0.877 and 0.833 for NMOSD, and 0.925 and 0.883 for MOGAD.

Conclusions: These results suggest that the MFIS-K, FSS, and FACIT-F are useful and valuable assessment instruments for evaluating fatigue in Korean patients with MS, NMOSD, and MOGAD.