Concurrent validity:

 

Multiple Sclerosis: (Rietberg, 2010; n= 43; ambulatory patients with MS; mean age 48.7 years; SD 7 years; 30 women; median Expanded Disability Status Scale score 3.5)

• Excellent: MFIS vs. Fatigue Severity Scale (FSS): r = 0.66; MFIS vs. the Checklist Individual Strength (CIS20R): r = 0.54

Multiple Sclerosis: (Tellez et al, 2005; (231 MS patients and 123 healthy controls, 164 patients with relapsing-remitting, 47 with secondary progressive, 12 with primary progressive)

• Excellent: between MFIS and FSS (r=0.68, p<0.0001)

• Adequate to Excellent: between MFIS subscale and FSS

  • MFIS-physical: r=0.75, p<0.0001

  • MFIS-cognitive: r=0.44, p<0.0001

  • MFIS-psychosocial: r= 0.62, p<0.0001

 

Predictive Validity:

 

Traumatic Brain Injury: (Sendroy-Terrill et al., 2010, n=243, 73% men, less than 5% of participants unconsciousness of < 1 day, 41 % showed LOC 1 day to 1 week, 31 % LOC from 1 week to 1 month, 24% had LOCs from 1 month to 1 year. Recived treatment in a comprehensive inpatient rehabilitation hospital. Cohorts based on years postinjury (1 to >30 years))

• MFIS-physical: with each additional decade of age at time of injury, there was a 2 point increase on the MFIS-physical score (P=.02)

• MFIS-psychosocial: with each additional decade of age at time of injury, there was a 0.5 point increase (P=.01)

 

Construct Validity

(Convergent/Discriminant)

Multiple Sclerosis: (Mills et al, 2010; n=415)

• Given the Rasch analysis, Mills et al. suggested that the physical and cognitive subscales should be used separately eliminating questions 4, 14, 17 from the physical and questions 1‐3, 5, and 11. In addition, the authors suggest the total score not be used.

Content Validity

Multiple Sclerosis: (Amtmann et al., 2012; n=1271 individuals with MS living in the community, 80% female, 36.2% reported being employed 20 or more hours a week. Mean age 507, mean disease duration 13.2 years, MS severity as minimal (EDSS≤4.0) for 32.4% and intermediate (EDSS 4.5-6.5) for 47.9% and advanced (EDSS≥7.0) for 19.7%)

• Validity: Spearman Rank Correlation Fatigue Severity Scale to MFIS:

  • Excellent for MFIS total and subscales of physical and psychosocial (0.69-0.77)

  • Adequate for MFIS cognitive subscale

• IRT analyses indicate that the FSS is less precise in measuring both low and high levels of fatigue, compared with the MFIS.

• For those interested in measuring both physical and cognitive aspects of fatigue, and whose sample is expected to have higher levels of fatigue, the MFIS is a better choice even though it is longer.

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Face Validity-Not Established