Minimally important difference of the fatigue severity scale and modified fatigue impact scale in people with multiple sclerosis

Abstract

Background: Fatigue is a common and debilitating symptom of Multiple Sclerosis (MS); however, it is unknown what constitutes a clinically significant change in fatigue. Establishing the minimally important difference (MID) of fatigue outcome measures can inform the interpretation of changes in fatigue by estimating the level of change that is considered clinically relevant. Aim: Determine the MID for the Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS) in people with MS. Methods: This cross-sectional study collected information on self-reported fatigue (FSS and MFIS) and quality of life (EQ-5D and MS Impact Scale 29) through an online survey. Anchor-based methods were used to estimate MID, and ordinal logistic regression models were used to determine the difference in fatigue that would predict a significant effect on quality of life. Results: 365 people with MS (81.9% female, 69.3% relapsing-remitting MS, mean age 46.2±11.6 years, mean time since diagnosis 9.6±8.7 years) responded to the survey. MID estimates for the FSS and MFIS ranged from 0.45-0.88 and 3.86-8.11 respectively, accounting for 6.4-12.6% of maximum FSS score and 4.6-9.7% of maximum MFIS score. Conclusions: MID estimates derived from this study indicate that a difference of at least 0.45 points on the FSS or 4 points on the MFIS constitutes a clinically significant difference in fatigue. Therefore, these estimates represent a threshold value which can be used to interpret changes in the FSS and MFIS over time or in response to an intervention.

Pilot randomized active-placebo-controlled trial of low-dose ketamine for the treatment of multiple sclerosis–related fatigue

“…A recent paper reported the minimal clinically important difference (MCID) in the FSS and MFIS scores in patients with MS to be 0.45 and 4 points, respectively. 32 Another study reported the MCID in the MFIS score in patients with Parkinson’s disease was 13.8. 33 The change from the baseline in both FSS (at 1 week) and MFIS (at day 28) in our study was greater than these minimally important differences reported in the literature.…”

“…FSS and MFIS are commonly used fatigue measures in MS studies, have been extensively validated, 31 and in the case of MFIS, has been recommended as the instrument of choice for the evaluation of fatigue in MS. 7 MFIS measures the impact of fatigue in multiple domains, including physical, cognitive, and psychosocial. Observing a major therapeutic effect of ketamine on the MFIS and its subdomains at day 28 32 Another study reported the MCID in the MFIS score in patients with Parkinson's disease was 13.8. 33 The change from the baseline in both FSS (at 1 week) and MFIS (at day 28) in our study was greater than these minimally important differences reported in the literature.…”

Health Problems Questionnaire in Multiple Sclerosis Patients: Development and Validation

“…In the different studies were used separate questionnaires to assess the problems of patients with MS, for example measurement of fatigue through FSS scale (29), stress, anxiety and depression through DSAA 21 scale (30), physical problems using several questionnaires (12, 31 -32). The MSHPQ scale evaluate all of the health problems including physical, psychological, emotional, family and socio -economic problems in MS patients in a single questionnaire.…”

Study protocol: randomised controlled trial evaluating exercise therapy as a supplemental treatment strategy in early multiple sclerosis: the Early Multiple Sclerosis Exercise Study (EMSES)

“…79 The MFIS score ranges from 0 to 84, with higher scores indicating greater fatigue impact and a change ranging from 3.86 to 8.11 being clinically relevant. 80 All of these questionnaires will be completed at baseline, after 24 weeks, after 48 weeks, and again at 1-year follow-up.…”