Fatigue Scale for Motor and Cognitive Functions

Multiple Sclerosis (MS): (Penner et al., 2009; n = 309 MS patients, mean age = 43.4 (9.9) years, female = 206 (67%) and 147 healthy controls, mean age = 41.7 (12.9) years, female = 92 (63%), MS type: 199 (64%) relapsing-remitting, 79 (26%) secondary progressive, and 31 (10%) primary progressive)

• Cut-off scores for the total scale:
• ≥ 43 Mild Fatigue
• ≥ 53 Moderate Fatigue
• ≥ 63 Severe Fatigue

• Cut-off scores for cognitive subscale:
• ≥ 22 Mild Cognitive Fatigue
• ≥ 28 Moderate Cognitive Fatigue
• ≥ 34 Severe Cognitive Fatigue

• Cut-off scores for the motor subscale:
• ≥ 22 Mild Motor Fatigue
• ≥ 27 Moderate Motor Fatigue
• ≥ 32 Severe Motor Fatigue

Multiple Sclerosis (MS): (Penner et al, 2009; n = 309 MS patients and 147 healthy controls in the validation study)

• Excellent test retest reliability for total, motor and cognitive (r = 0.87; r = 0.86; r = 0.85)

Multiple Sclerosis: (Penner et al., 2009; n = 308)

• Excellent: Cronbach’s alpha for MS patient group ≥ 0.91* for both subscales and total scale

*Scores higher than 0.9 may indicate redundancy in the scale questions.

Predictive validity:

Multiple Sclerosis: (Penner et al., 2009)

• Excellent predictive validity of the FSMC total and motor subscale in relating fatigue to the underlying diagnosis of MS (ROC = 0.93 (sensitivity = 88.7, specificity = 83.0)  and 0.94 (sensitivity = 89.0, specificity = 86.4), respectively)
• Adequate predictive validity of the FSMC cognitive subscale in relating fatigue to the underlying diagnosis of MS (ROC = 0.88 (sensitivity = 86.4, specificity = 66.7))
• Compared with the Modified Fatigue Impact Scale (MFIS) and the Fatigue Severity Scale (FSS), the FSMC consistently showed the largest ROC area and superior values for sensitivity and specificity.

Convergent validity:

Multiple Sclerosis: (Penner et al., 2009)

• Excellent correlations between scores on the FSMC subscales and total scale and the MFIS total score (r = 0.763-0.829, p < 0.01)
• Excellent correlations between scores on the FSMC subscales and total scale and the FSS total score (r = 0.684-0.797, p < 0.01)
• Excellent correlations between scores on the FSMC cognitive subscale and total scale and the MFIS cognitive subscale (r = 0.832 and r = 0.756, respectively, p < 0.01)
• Excellent correlations between scores on the FSMC motor subscale and total scale and the MFIS motor subscale (r = 0.804 and r = 0.732, respectively, p < 0.01)
• Adequate correlations between scores on the FSMC subscales and total scale and fatigue rated by neurologists (r = 0.444-0.508, p < 0.01)
• Adequate correlations between scores on the FSMC motor subscale and the Multiple Sclerosis Functional Composite (r = -0.342, p < 0.01)
• Adequate correlations between scores on the FSMC subscales and total and the mean score on the Beck Depression Inventory (r = 0.42-0.49, p < 0.01)
• Adequate correlation between scores on the FSMC motor subscale the mean score on the EDSS (r = 0.38, p < 0.01)
• Poor correlation between scores on the FSMC cognitive subscale and the Multiple Sclerosis Functional Composite (r = -0.206, p < 0.01)
• Poor correlations between scores on the FSMC motor subscale and total and the mean score on the 9-Hole Peg Test (r = 0.22, p < 0.05 and r = 0.15, p < 0.05, respectively)
• Poor correlations between scores on the FSMC motor subscale and total and the mean score on the 25-Foot Walk Test (r = 0.22, p < 0.01 and r = 0.14, p < 0.05, respectively)

Discriminant validity:

Multiple Sclerosis: (Penner et al., 2009)

• Excellent correlations between scores on the FSMC subscales and total and depression rated by neurologists (r = 0.21-0.24, p < 0.01)
• Excellent correlations between scores on the FSMC cognitive subscale and total and the mean score on the Expanded Disability Status Scale (EDSS) (r = 0.13, p < 0.05 and r = 0.27, p < 0.01, respectively)

Multiple Sclerosis: (Penner et al., 2009)

• Sensitivity to fatigue with underlying diagnosis of MS: High sensitivity for FSMC total scale and both cognitive and motor subscales.

ROC Analysis Results by Fatigue Scale

FSMC-T: Total score of FSMC, FSMC-C: Cognitive subscale of FSMC, FSMC-M: Motor subscale of FSMC; MFIS: Modified Fatigue Impact Scale; FSS: Fatigue Severity Scale; following abbreviations for the MFIS and FSS are the same as for the FSMC

• Either no overlap or an overlap of less than 30% of the 90% CI width of the ROC areas between the FSMC and the other two scales indicates a substantial difference between the individual measures.
• Comparison of the ROC curves for each of the scales revealed that the FSMC is not only superior to the both the MFIS and the FSS for the total score, but also for the cognitive and motor subscales.

Stroke: (Goh et al., 2023; n = 34, mean age = 55.26 (12.27) years, age range = 18-90 years; history of unilateral stroke >6 months prior to enrollment)

• FMSC-Total: highest SEM = 9.08
• FMSC-Motor: lowest SEM = 4.26
• FMSC-Cognitive: SEM = 5.03

Stroke: (Goh et al., 2023)

• FSMC-Total = 25.17 (25.17%)
• FSMC-Motor = 11.81 (23.62%)
• FSMC-Cognitive = 13.94 (13.94%)

Stroke: (Goh et al., 2023; retest interval = one week)

• Acceptable test-retest reliability for FSMC total and subscales:
  • FSMC-Total (ICC = 0.76)
  • FSMC-Motor highest score (ICC = 0.81)
  • FSMC-Cognitive had the lowest score (ICC = 0.72)

Stroke: (Goh et al., 2023)

• Excellent internal consistency for FSMC total and subscales:
  • FSMC-Total: Cronbach’s alpha = 0.96*
  • FSMC-Motor: Cronbach’s alpha = 0.92*
  • FSMC-Cognitive: Cronbach’s alpha = 0.91*

*Scores higher than 0.9 may indicate redundancy in the scale questions.

Concurrent validity:

Stroke:  (Goh et al., 2023)

• Excellent concurrent validity between the FSMC and the FSS (ρ = 0.66-0.72)
• Adequate concurrent validity between the FSMC and the Visual Analog Scale-Fatigue (ρ = 0.37-0.41)

Stroke:  (Hubacher et al., 2012; n = 31, mean age = 59.29 (10.30) years, age range = 35-76 years, male = 25 (81%); inclusion criteria: no other neurological of psychiatric diseases; lesion types: cortical (n = 6), sub-cortical (n = 19), mixed sub-cortical and cortical (n = 6))

• Excellent correlations of the FSMC-Total scale and FSMC-Cognitive subscale with the Beck Depression Inventory-Fast Screen (BDI-FS) (r = 0.61, p < 0.001 for both, n = 29)
• Adequate correlation between the FSMC-Motor subscale with the Beck Depression Inventory-Fast Screen (BDI-FS) (r = 0.54, p = 0.002, n = 29)

Discriminant validity:

Stroke: (Hubacher et al., 2012; n = 31, mean age = 59.29 (10.30) years, age range = 35-76 years, male = 25 (81%); inclusion criteria: no other neurological of psychiatric diseases; lesion types: cortical (n = 6), sub-cortical (n = 19), mixed sub-cortical and cortical (n = 6))

• For the FSMC-Cognitive subscale, patients with cortical lesions reached the highest values, while patients with subcortical lesions had the lowest values (Moderate effect size of d = 0.21)
• For the FSMC-Motor subscale the opposite was found: patients with cortical lesions showed less fatigue symptoms than patients with subcortical lesions (Moderate effect size of d = -0.23)
• Patients with mixed lesions showed values between the FSMC-Cognitive and FSMC-Motor groups.
• The FSMC-Total score did not differ among the three groups.

Stroke: (Hubacher et al., 2012; n = 31 stroke patients and 31 age-matched healthy controls)

• Sensitivity and Specificity of scale with respect to its ability to relate fatigue to the stroke diagnosis:
  • Sensitivity: 64.5%
  • Specificity: 71.0%
• Significantly (p < 0.05) increased fatigue symptoms on the FSMC-Total and both the Cognitive and Motor subscales after 4 weeks:

Fatigue Scores at Baseline and After 4 Weeks

FSS: Fatigue Severity Scale; MFIS: Modified Fatigue Impact Scale; FSMC-C: Cognitive subscale of FSMC; FSMC-M: Motor subscale of FSMC; FSMC-T: Total score of FSMC