Primary Image

RehabMeasures Instrument

Last Updated


The 9-item scale which measures the severity of fatigue and its effect on a person's activities and lifestyle in patients with a variety of disorders.

Link to Instrument

Instrument Details

Acronym FSS

Area of Assessment

Activities of Daily Living
Life Participation

Assessment Type

Patient Reported Outcomes

Administration Mode

Paper & Pencil




  • Cancer Rehabilitation
  • Multiple Sclerosis
  • Parkinson's Disease & Movement Disorders
  • Stroke Recovery

Key Descriptions

  • A 9-item questionnaire with questions related to how fatigue interferes with certain activities and rates its severity according to a self-report scale.
  • The items are scored on a 7 point scale with 1 = strongly disagree and 7= strongly agree.
  • The minimum score = 9 and maximum score possible = 63. Higher the score = greater fatigue severity.
  • Another way of scoring: mean of all the scores with minimum score being 1 and maximum score being 7.
  • Lerdal (2011) found that items 1 and 2 in the FSS-9 should not be used in a mean score because the FSS-7 shows better validity and reliability and is likely more sensitive for measuring change in fatigue.

Number of Items


Equipment Required

  • Pen

Time to Administer

Less than 5 minutes

Required Training

No Training

Instrument Reviewers

Initially reviewed by Avisha Shah in 10/2012; Updated by Terry Ellis, PT, PhD, NCS and Laura Savella SPT in 2013; Updated by Kent Bubel, OTS, Eva Jarek, OTS and Camara Singleton, OTS in 2016.

ICF Domain


Measurement Domain

General Health

Professional Association Recommendation

Recommendations for use of the instrument from the Neurology Section of the American Physical Therapy Association’s Multiple Sclerosis Taskforce (MSEDGE), Parkinson’s Taskforce (PD EDGE), Spinal Cord Injury Taskforce (PD EDGE), Stroke Taskforce (StrokEDGE), Traumatic Brain Injury Taskforce (TBI EDGE), and Vestibular Taskforce (Vestibular EDGE) are listed below. These recommendations were developed by a panel of research and clinical experts using a modified Delphi process.

For detailed information about how recommendations were made, please visit:




Highly Recommend




Reasonable to use, but limited study in target group  / Unable to Recommend


Not Recommended

Recommendations Based on Parkinson Disease Hoehn and Yahr stage:














Recommendations for entry-level physical therapy education and use in research:


Students should learn to administer this tool? (Y/N)

Students should be exposed to tool? (Y/N)

Appropriate for use in intervention research studies? (Y/N)

Is additional research warranted for this tool (Y/N)





Not reported


Lerdal (2011) found that items 1 and 2 in the FSS-9 should not be used in a mean score because the FSS-7 shows better validity and reliability and is likely more sensitive for measuring change in fatigue.

Parkinson’s Disease:

  • At this point no studies report psychometrics in a sample of patients in H&Y Stage 5 and only one study includes pts in H&Y Stage 4

  • In a study examining the effects of exercise on fatigue in persons with PD (H&Y Stages 0-4), no significant changes were observed in FSS scores, questioning its responsiveness to change in an exercise intervention.

  • The FSS can be used to distinguish between fatigued and non-fatigued people with PD. (Hagell et al, 2006)

  • The scale has been studied and evaluated for psychometrics in multiple sclerosis patients. Limited psychometric evaluation has been done in PD population. Further, research on FSS should be performed for patients with PD

  • The FSS is widely used as it is concise and easy to administer. But it is a little vague as it is subjective in nature & does not provide a precise definition of fatigue

  • It can be used as a good screening tool as it can easily distinguish between fatigued and non-fatigued people. Therefore, it is important that the FSS is adequately researched in PD population


Fatigue Severity Scale translations:




These translations, and links to them, are subject to the Terms and Conditions of Use of the Rehab Measures Database. RIC is not responsible for and does not endorse the content, products or services of any third-party website, and does not make any representations regarding its quality, content or accuracy. If you would like to contribute a language translation to the RMD, please contact us at

Do you see an error or have a suggestion for this instrument summary? Please e-mail us!

Multiple Sclerosis

back to Populations

Standard Error of Measurement (SEM)

Multiple Sclerosis: (Learmonth et al, 2013; Mean age 49.2 (9); Disease duration (years) mean 11.8 (8.2))

  • The SEM for the FSS was 0.7 points (mean = 5.1 points), indicating that a change of less than 0.7 points may be due to measurement error.

Minimal Detectable Change (MDC)

Multiple Sclerosis: (Learmonth et al, 2013)

  • The MDC provides an indication of clinically important change and is based on the SEM. The FSS had the smallest estimates of clinically important change; however, results indicated that a change in FSS score of 1.9 points (38% of the overall mean score) would be necessary to reflect a clinically important change.
  • The CV for the FSS indicated that a change in score of 10.3% or less may be expected over six months and therefore, this level of change or less could be interpreted as no change in fatigue.
  • Researchers and clinicians should be aware that a small change in FSS scores might be due to measurement error rather than a clinically relevant change.

Test/Retest Reliability

Multiple Sclerosis:

(Learmonth et. al., 2013; n=86, mean age=49.2(9), disease duration 11.8 (8.2).

  • Moderate: ICC = 0.751 over six months

Construct Validity

Convergent Validity:

Multiple Sclerosis:

Learmonth et al, 2013 n=82

  • Excellent (r = 0.754) correlation of FSS with MFIS
  • Adequate (r = 0.532) correlation of FSS with PDDS
  • Adequate (r = 0.350) correlation of FSS with HADS (anxiety)
  • Adequate (r = 0.456) correlation of FSS with HADS (depression)
  • Adequate (r = 0.466) correlation of FSS with SF-MPQ (sensory)
  • Adequate (r = 0.569) correlation of FSS with SF-MPQ (affective)
  • Adequate (r = 0. 0.491) correlation of FSS with PSQI
  • Excellent (r = 0.628) correlation of FSS with MSWS-12
  • Adequate (r = −0.405) correlation of FSS with 6 MW
  • Poor (r = −0.263) correlation of FSS with SDMT


(Téllez et al, 2005)—Excellent (r=0.68, p)

Parkinson's Disease

back to Populations

Normative Data

Parkinson’s Disease:

(Hagell et al, 2006; = 118, mean age = 63.9(9.6) years, mean time post PD = 8.4 (5.7) years)

  • Mean SD (FSS) score for PD patients; 3.9 (1.6), range 2.6-5.2

(Winward et al; n = 37; H&Y Stages 0 - 4; mean age = 64.1(8.17)

  • Mean FSS Score = 4.08 (1.46); FSS Scored 0 - 7

(Fereshtehnejad et al, 2013; n = 90, mean age = 62.0 (10.7) years, mean duration of disease = 6.0 (4.8) years)

  • Mean FSS Score = 4.4 (2.0), range 1-7

Test/Retest Reliability

Parkinson's Disease:

(Valderramas et al, 2012; n = 30, mean age = 62 (11) years, mean time post- PD = 7.6 (6.5) years)

  • The evaluation of the FSS-BR (Fatigue Severity Scale-Brazilian-Portuguese version) suggests an excellent Test-retest reliability (ICC = 0.91)

Internal Consistency

Parkinson’s Disease:

(Hagell et al, 2006)

  • Excellent internal consistency (Cronbach’s alpha = 0.94)

(Grace et al, 2006)

  • Excellent split half reliability (Cronbach’s alpha = 0.86 and 0.91)
  • For 8 out of the 9 items, Adequate-Excellent (0.44-0.78) correlation was observed.
  • For item 2, Poor (0.27) correlation was seen.

Construct Validity

Convergent Validity:

Parkinson’s Disease:

  • Excellent (= -0.77) negative correlation with Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale (Hagell et al, 2006).
  • Excellent (= 0.62) correlation with Nottingham Health Profile (NHP-EN) scale (Hagell et al, 2006).
  • Excellent (= 0.84) correlation with Parkinson’s Fatigue (PFS) scale (Grace et al, 2006).
  • Poor-adequate (= 0.22-0.47) correlation with Parkinson’s Disease Questionnaire-39 (PDQ-39) scale (Herlofson et al, 2003; = 66, mean age = 70.8 (9.9) years, time since PD = 70.2 (56.1) months).
  • Adequate (= 0.37) correlation with MOS-SF-36 scale (Herlofson et al, 2003).
  • Poor (= 0.19) correlation with Hamilton Depression Rating (HAM-D) scale (Garber CE & Friedman JH, 2003; = 37)
  • Excellent (r = 0.80) correlation with Fatigue rating Scale (Grace et al, 2006)
  • Poor-adequate (r = 0.22-0.47) correlation with Parkinson’s Disease Questionnaire-39 (PDQ-39) scale (Herlofson et al, 2003; n = 66, mean age = 70.8 (9.9) years, time since PD = 70.2 (56.1) months)
  • Excellent (r = 0.93) correlation of FSS-BR with PDQ-39 (Valderramas et al, 2012)
  • Excellent (r = 0.75) correlation of FSS-BR with Beck Depression Inventory (Valderramas et al, 2012)
  • Adequate (r = 0.40) correlation of FSS-BR with Hoehn & Yahr scale (Valderramas et al, 2012)
  • Adequate (r = 0.45) correlation of the FSS-BR with UPDRS (Valderramas et al, 2012)
  • Adequate (r = 0.37) correlation with MOS-SF-36 scale (Herlofson et al, 2003)
  • Poor (r = 0.19) correlation with Hamilton Depression Rating (HAM-D) scale (Garber CE & Friedman JH, 2003; n = 37)
  • Excellent (r = 0.80) correlation with Fatigue rating Scale (Grace et al, 2006)
  • Poor (r = -0.184) correlation of FSS with 6 minute walk test (Garber CE & Friedman JH, 2003)

Floor/Ceiling Effects

Parkinson’s Disease:

(Hagell et al, 2006)

  • The Floor/Ceiling effects were adequate (2.5%) for a sample of PD patients.


Parkinson’s Disease:

Responsiveness to Pharmocological Intervention Mendoca et al, 2007; n = 17 treatment arm, receiving methyphenidate; mean age = 62.2(10), mean H&Y Stage = 2.58(0.5); n = 19 placebo arm, mean age = 66.3(7.6), mean H&Y Stage = 2.38(0.3)

  • Those persons in the treatment arm had a significant (p < 0.04) reduction in FSS Score by 6.5 points (from FSS = 43.8 at baseline); Cohen’s d = 0.79
  • Smaller reductions in the placebo group did not reach levels of significance Response to Exercise Intervention: Winward et al, 2010; H&Y 0-4. n = 20 exercise group, mean age = 63.4(6.7); n = 19 control group, mean age = 64.9(9.6)
  • No significant difference in score reduction between exercise and control group at 12 weeks.

Non-Specific Patient Population

back to Populations

Standard Error of Measurement (SEM)

Obesity: (Impellizzeri et al, 2013; n=220, mean age=47 (15)) 

  • The agreement as measured using the SEM was 0.43 (0.36 to 0.54) corresponding to 13% (11 to 17%).

Minimal Detectable Change (MDC)

Obesity: (Impellizzeri et al, 2013) 

  • The MDC was 1.2 points (37%). Cronbach’s alpha was 0.94 and 0.93 at baseline and post-intervention, respectively.


Post-poliomyelitis Syndrome: (Koopman et al, 2014; n = 61, mean age = 59 (10) years, mean time post onset of PPS = 14.2 (11.5) years) 

  • The smallest detectable change for FSS (range 1-7) was 1.55 or 28.7%, which represents the percentage of the means of the FSS and CIS20-F. The authors found this SDC to be high and therefore insufficiently sensitive to detect changes beyond measurement error in single individuals. However, much smaller changes can be detected at the group level.

Normative Data

Healthy Population:

(Grace et al, 2006; = 16, mean age = 69.94 years)

  • Mean (SD) FSS scores for healthy individuals; 2.3 (0.7)


Post-poliomyelitis Syndrome: (Koopman et al, 2014; n = 61, mean age = 59 (10) years, mean time post onset of PPS = 14.2 (11.5) years)

  • Mean FSS Score = 5.3 (1.3), range 1-7


Epilepsy: (Hernandez-Ronquiloa et al, 2011)

PWE (patients with epilepsy) mean age = 36.5 (16.8) 
PMS (patients with different neurological problems) mean age = 40.2 (10 ) 
HV (healthy volunteers) mean age = 39.6 (11.5)

  • Healthy (HV) (n=34), Mean fatigue 2.6 (1.1)
  • Epilepsy (PWE) (n=67), Mean fatigue 4.2 (1.5)
  • MS (PMS) (n = 30), Mean fatigue 4.8 (1.4)
  • Migraine (PMS) (n = 19), Mean fatigue 4.4 (1.9)
  • Radiculopathy (PMS) (n = 7), Mean fatigue 4.5 (0.9)

Test/Retest Reliability

Post-Poliomyelitis Syndrome:

(Koopman et al, 2014; n = 61, mean age = 59 (10) years, mean time post-onset of PPS = 14.2 (11.5) years)

  • ICC (95% CI) = 0.80 Excellent


Chronic Hepatitis C:

(Rosa et al, 2014; n = 386, 462, mean age = 48.9(10.36), 44(11.81) years)

  • ICC = 0.74, 0.86 Excellent test-retest reliability.



(Impellizzeri et al, 2013; n=220, mean age=47 (15)

  • ICC = 0.89 (0.82 to 0.94) Excellent

Interrater/Intrarater Reliability


(Hernandez-Ronquilloa et al, 2011)

  • The intra-observer reliability for the FSS in PWE (patients with epilepsy) was 0.85

Internal Consistency

Post-Poliomyelitis Syndrome:

(Koopman et al, 2014) — Acceptable internal consistency (Cronbach’s alpha = 0.90)


Chronic Hepatitis C:

(Rosa et al, 2014)—Excellent internal consistency (Cronbach’s alpha = 0.96, 0.96 across two studies)


Criterion Validity (Predictive/Concurrent)

Chronic Hepatitis C: (Rosa et al, 2014; PILLAR: n=386, mean age 44.0(11.81); ASPIRE: n=462, mean age 48.9(10.36)) Excellent correlation of concurrent validity (PILLAR: r= -0.63, ASPIRE: -0.66) between the total FSS score and with EQ-5D VAS PILLAR represented treatment-naïve patients while ASPIRE represented treatment-experienced patients with Chronic Hepatitis C infection.

Construct Validity

Convergent Validity:

(Ghajarzadeh et al, 2012)

Excellent (r=0.69, p



(Impellizzeri et al, 2013; n=220, mean age=47 (15)—At baseline:

  • Adequate (r = 0.58; 95% CI 0.48 to 0.66) correlations were found between FSS and POMS Fatigue score
  • Adequate (r = −0.53; 0.43 to 0.62) FSS and POMS Vigor was significantly negative and moderate large
  • Adequate (r = 0.41, 0.29 to 0.51) The correlation between the change scores in FSS and POMS-Fatigue was positive and moderate
  • Poor (r = −0.26, 0.13 to 0.38) POMS-Vigor the correlation was negative and small.
  • Adequate (r = 0.52, 0.42 to 0.61) Moderate-large correlations were also found between FSS and ORWELL97
  • Poor (r = 0.29, 0.16 to 0.41).small moderate correlation was found between change scores of the two questionnaires.
  • Poor (r = 0.15, 0.02 to 0.28) The correlation between FSS and BMI was significant but small, however, when adjusted for age the correlation increased to r = 0.25 (0.12 )

Floor/Ceiling Effects

Post-poliomyelinits Syndrome:

(Koopman et al, 2014)—Both questionnaires had adequate floor and ceiling effects, with less than 15% of the post-polio patients demonstrating highest and lowest possible scores.


Chronic Hepatitis C:

(Rosa et al, 2014)—Floor / Ceiling effects were adequate (Floor: 4.9% (PILLAR) and 8% (ASPIRE); Ceiling 1.2% (PILLAR) and 2.7% (ASPIRE).



(Impellizzeri et al, 2013; n=220, mean age=47 (15)—Taking into account the MDC, the floor and ceiling effects post-intervention were 5%. The floor and ceiling effects were lower than the 15% cut-off value considered acceptable.


Chronic Hepatitis C:

(Rosa et al, 2014)—The FSS showed responsiveness, however, neither PILLAR nor ASPIRE achieved statistical significance (p



(Impellizzeri et al, 2013; n=220, mean age=47 (15)—Significant moderate changes were found for all the instruments and BMI after the three-week intervention. The internal responsiveness of FSS was comparable to the ORWELL97.

Musculoskeletal Conditions

back to Populations

Test/Retest Reliability

Congenital Myopathy:

(Werlauff et al, 2013, n=71, mean age 34.2 (14.4)

  • Adequate test-retest reliability (0.72)

Internal Consistency

Congenital Myopathy:

(Werlauff et al, 2013)—Excellent internal consistency (Cronbach’s alpha = 0.89), IRC ranged from 0.80 to 0.30, item 1 has weakest correlation

Chronic Pain

back to Populations

Test/Retest Reliability

Chronic Neck Pain:

(Takasaki & Treleaven, 2013; n = 26, mean age = 35.4 (12.1) years, mean symptom duration = 36.6 (26.4).

  • Test-retest reliability was examined using quadratic-weighted kappa (>0.4) and was considered adequate.

Internal Consistency

Chronic Neck Pain:

(Takasaki & Treleaven, 2013)—Good internal consistency (Cronbach’s alpha = 0.81 ≤ α ≤ 0.89)

Construct Validity

Convergent Validity:

Chronic Neck Pain:

(Takasaki & Treleaven, 2013)—Excellent (0.63 ≤ r ≤ 0.78) correlation of FSS-7 with the Fatigue Impact Scale, Adequate (r = 0.42) correlation of FSS-7 with the Visual Analog Fatigue Scale.


back to Populations

Criterion Validity (Predictive/Concurrent)

Stroke: (Lerdal & Kottorp, 2011) Cronbach’s alpha for the FSS-9 was 0.86 (adequate) at baseline while the alpha in the FSS-7 varied between 0.87 and 0.93 at four measurement times, supporting item reliability in the FSS-7. At baseline (n=119): 0.87; adequate 6 months (n=106): 0.92; excellent 12 months (n=104): 0.93; excellent 18 months (n=99): 0.92; excellent “Analyses of the concurrent validity of the FSS-7 showed a moderate to high relationship with SF-36-vitality and a moderate relationship with the one-item perceived energy item” (p. 1263).

Spinal Injuries

back to Populations

Internal Consistency

Spinal Muscular Atrophy Type II:

(Werlauff et al, 2013)—Excellent internal consistency (Cronbach’s alpha = 0.92)

  • IRC weak in item 1 (0.49) and item 2 (0.69)
  • Excellent internal consistency amongst three factors
  • Cronbach’s alpha = 0.84 for physical status questions
  • Cronbach’s alpha = 0.94 for cognitive status questions
  • Cronbach’s alpha = 0.80 for psychosocial function status questions

Mixed Populations

back to Populations

Cut-Off Scores

Multiple Sclerosis and Systemic Lupus Erthymatosus:

(Krupp et al, 1989; n = 74, mean age = 40.2 years)

  • The cut-off score is 36 where a score > 36 may indicate severe fatigue or need for further evaluation.


Fereshtehnejad, S., Hadizadeh, H., Farhadi, F., Shahidi, G. A., Delbari, A., & Lökk, J. (2013). Reliability and validity of the persian version of the fatigue severity scale in idiopathic parkinson's disease patients. Parkinson's Disease, 2013, 935429. Find it on PubMed

Garber, C. E. and Friedman, J. H. (2003). "Effects of fatigue on physical activity and function in patients with Parkinson's disease." Neurology 60(7): 1119-1124. Find it on PubMed

Ghajarzadeh. M., Rozita Jalilian, Ghazaleh Eskandari, Mohammad Ali Sahraian, & Amir Reza Azimi. 2012. Validity and reliability of Persian version of Modified Fatigue Impact Scale (MFIS) questionnaire in Iranian patients with multiple sclerosis. Disability and Rehabilitation, 35(18): 1509-1512. Find it on PubMed

Grace, J., Mendelsohn, A., et al. (2007). "A comparison of fatigue measures in Parkinson's disease." Parkinsonism Relat Disord 13(7): 443-445. Find it on PubMed

Hagell, P., Hoglund, A., et al. (2006). "Measuring fatigue in Parkinson's disease: a psychometric study of two brief generic fatigue questionnaires." J Pain Symptom Manage 32(5): 420-432. Find it on PubMed

Herlofson, K. and Larsen, J. P. (2003). "The influence of fatigue on health-related quality of life in patients with Parkinson's disease." Acta Neurol Scand 107(1): 1-6. Find it on PubMed

Hernandez-Ronquillo, L., Moien-Afshari, F., Knox, K., Britz, J., Tellez-Zenteno, J. F. (2011). How to measure fatigue in epilepsy? The validation of three scales for clinical use. Epilepsy Research. Volume 95, Issues 1–2, , 119–129 Find it on PubMed

Impellizzeri, F. M., Agosti, F., De Col, A., & Sartorio, A. (2013). Psychometric properties of the Fatigue Severity Scale in obese patients. Health and Quality of Life Outcomes 2013, 11:32. Find it on PubMed

Koopman, F. S., Brehm, M. A., Heerkens, Y. F., Nollet, F., & Beelen, A. (2014). Measuring fatigue in polio survivors: Content comparison and reliability of the fatigue severity scale and the checklist individual strength. Journal of Rehabilitation Medicine, 46(8), 761. Find it on PubMed

Krupp, L. B., LaRocca, N. G., et al. (1989). "The fatigue severity scale. Application to patients with multiple sclerosis and systemic lupus erythematosus." Arch Neurol 46(10): 1121-1123. Find it on PubMed

Learmonth,Y.C., D. Dlugonski, Pilutti, L.A., Sandroff, B.M., Klaren, R., & Motl R.W. (2013). Psychometric properties of the Fatigue Severity Scale and the Modified Fatigue Impact Scale. Journal of the Neurological Sciences 331, 102–107. Find it on PubMed

Lerdal, A., & Kottorp, A. (2011). Psychometric properties of the fatigue severity Scale—Rasch analyses of individual responses in a norwegian stroke cohort. International Journal of Nursing Studies, 48(10), 1258-1265.Find it on PubMed

Rosa, K., Fu, M., Giles, L., Cerri, K., Peeters, M., Bubb, J., & Scott, J. (2014). Validation of the Fatigue Severity Scale in chronic hepatitis C. Health and Quality of Life Outcomes. 12(90).Find it on PubMed

Takasaki, H., & Treleaven, J. (2013). Construct validity and test-retest reliability of the fatigue severity scale in people with chronic neck pain. Archives of Physical Medicine and Rehabilitation, 94(7), 1328-1334.Find it on PubMed

Téllez, N., Río, J., Tintoré, M., Nos, C., Galán, I., & Montalban, X. (2005). Does the Modified Fatigue Impact Scale offer a more comprehensive assessment of fatigue in MS?. Multiple Sclerosis. 11: 198-202.Find it on PubMed

Valderramas, S., Feres, A. C., et al. (2012). "Reliability and validity study of a Brazilian-Portuguese version of the fatigue severity scale in Parkinson's disease patients." Arq Neuropsiquiatr 70(7): 497-500. Find it on PubMed

Werlauff, U., Hojberg, A., Firla-Holme, R., Steffenson, B.F., & Vissing, J. (2014). Fatigue in patients with spinal muscular atrophy type II and congenital myopathies: evaluation of the fatigue severity scale. Quality of Life Research. 23: 1479-1488Find it on PubMed