Short Fatigue Questionnaire

1. Abstract

The Short Fatigue Questionnaire (SFQ; in Dutch: Verkorte Vermoeidheidsvragenlijst) is a brief, psychometrically validated self-report instrument designed to quantify the severity and intensity of physical fatigue over the preceding two-week reference period. Developed by Alberts, Smets, Vercoulen, Garssen, and Bleijenberg (1997) at the Radboud University Nijmegen Medical Centre and the Academic Medical Center Amsterdam, the SFQ was constructed to serve as an efficient screening counterpart to the more extensive, 20-item Checklist Individual Strength (CIS) and the Multidimensional Fatigue Inventory (MFI-20). Comprising exactly four items, the questionnaire captures a strictly unidimensional construct centered on physical fatigue and somatic exhaustion. Each item is rated on a 7-point Likert scale ranging from 1 (“Yes, that is true”) to 7 (“No, that is not true”), yielding a summative composite score between 4 and 28 points, wherein higher scores denote higher fatigue severity after reversing positively keyed items. Extensive psychometric evaluations demonstrate high internal consistency (Cronbach’s alpha spanning .88 to .92 across clinical and community samples), robust convergent validity with longer fatigue inventories (Pearson correlations r > .80 with the CIS fatigue severity subscale), and solid discriminant validity differentiating healthy community controls from patients with chronic fatigue syndrome (CFS/ME), cancer-related fatigue, multiple sclerosis, and chronic inflammatory conditions. Confirmatory factor analyses establish an unambiguous single-factor structure with factor loadings exceeding .75 across diverse cohorts. With an empirical cut-off score of 18 or higher reliably identifying clinically relevant, debilitating fatigue, the SFQ serves as a rapid, reliable, and resource-efficient measurement tool in primary care triage, epidemiological studies, oncological surveillance, and clinical trials where participant burden must be minimized.

2. Keywords

Short Fatigue Questionnaire, Verkorte Vermoeidheidsvragenlijst, SFQ, fatigue severity, physical exhaustion, psychometrics, chronic fatigue syndrome, cancer-related fatigue, screening instrument, unidimensional assessment, Checklist Individual Strength, patient-reported outcome measures

3. Authors

The Short Fatigue Questionnaire was conceived, developed, and validated through collaborative clinical research conducted across several premier academic institutions in the Netherlands, primarily within behavioral medicine, medical psychology, and chronic fatigue research units:

• M. Alberts, Ph.D. — Expert in clinical psychology and health psychology, formerly affiliated with the Expert Centre for Chronic Fatigue (ECCF / Kenniscentrum Chronische Vermoeidheid), Radboud University Medical Center (Radboudumc), Nijmegen, the Netherlands.
• Ellen M. A. Smets, Ph.D. — Professor of Medical Communication, Department of Medical Psychology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands. Co-developer of the Multidimensional Fatigue Inventory (MFI-20).
• Joris H. M. M. Vercoulen, Ph.D. — Clinical psychologist and Associate Professor, Department of Medical Psychology and Pulmonary Diseases, Radboud University Medical Center, Nijmegen, the Netherlands. Primary architect of the Checklist Individual Strength (CIS).
• Bert Garssen, Ph.D. — Senior researcher in psychoneuroimmunology and psycho-oncology, formerly affiliated with the Helen Dowling Institute for Psycho-Oncology, Bilthoven, the Netherlands.
• Gijs Bleijenberg, Ph.D. — Emeritus Professor of Medical Psychology and founding director of the Expert Centre for Chronic Fatigue, Radboud University Medical Center, Nijmegen, the Netherlands; internationally recognized pioneer in the cognitive-behavioral conceptualization and intervention for chronic fatigue syndrome.

4. Purpose

Fatigue is among the most pervasive, debilitating, and economically burdensome symptoms encountered in both primary medical care and specialized clinical practice. It manifests across a wide spectrum of physiological and psychiatric conditions, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), malignant neoplasms, post-viral sequelae, autoimmune disorders such as multiple sclerosis and rheumatoid arthritis, and mood disorders. Despite its high prevalence, comprehensive multidimensional fatigue instruments—such as the 20-item Checklist Individual Strength (CIS), the 20-item Multidimensional Fatigue Inventory (MFI-20), or the 29-item Fatigue Impact Scale (FIS)—impose considerable cognitive and logistical burdens on severely debilitated patients, elderly respondents, and high-throughput epidemiological surveys. The primary purpose of the Short Fatigue Questionnaire (SFQ) is to resolve this clinical and methodological dilemma by providing an ultra-brief, psychometrically uncompromising instrument designed exclusively to measure the subjective severity and intensity of physical fatigue.

In routine clinical practice, the SFQ functions as a primary screening instrument to detect individuals suffering from severe, persistent exhaustion who require secondary diagnostic workups or tailored interventions, such as cognitive behavioral therapy (CBT) or graded exercise therapy (GET). Because the questionnaire requires less than one minute to complete, clinicians can seamlessly embed it into standard medical intake batteries, waiting room kiosks, or electronic health records without disrupting patient workflow. The provision of established normative thresholds—most notably the validated cut-off score of 18—enables general practitioners and specialists to differentiate normative physiological weariness from clinically significant, maladaptive exhaustion with high sensitivity and specificity.

In medical and behavioral research, the SFQ serves multiple vital functions. In large-scale epidemiological investigations where survey space is constrained by multi-instrument protocols, the SFQ captures fatigue severity without inducing respondent fatigue or non-response attrition. In longitudinal randomized controlled trials (RCTs) evaluating pharmaceutical agents, immunotherapies, or psychosocial interventions, the SFQ offers a sensitive repeated-measures outcome tool capable of tracking symptom trajectories over time. Furthermore, because its items were directly adapted from the core fatigue severity dimension of the Dutch gold-standard CIS, empirical findings generated with the SFQ remain directly comparable to historical research cohorts assessed via longer diagnostic instruments.

5. Psychological Construct

The psychological construct evaluated by the Short Fatigue Questionnaire is subjective physical fatigue severity, conceptualized as a chronic or subacute state of perceived physical weariness, depleted energy reserves, and diminished bodily vigor. Contemporary psychometric theory distinguishes between multi-faceted models of fatigue—which incorporate cognitive fatigue, psychological fatigability, motivational deficits, and behavioral activity reduction—and unidimensional models that isolate the raw somatic sensation of exhaustion. The SFQ explicitly adopts this latter, focused approach.

Fatigue, from a phenomenological perspective, is not merely the extreme end of normal sleepiness or acute physical exertion. Rather, pathological physical fatigue represents an overwhelming sense of systemic exhaustion that is disproportionate to previous exertion levels, poorly relieved by restorative sleep, and disruptive to daily functional capacity. The construct measured by the SFQ encapsulates four interdependent manifestations of this somatic state:

• Self-Perceived Somatic Tiredness: The overarching, subjective evaluation of bodily fatigue experienced consistently across daily activities (e.g., general feelings of being profoundly tired regardless of sleep duration).
• Physical Exhaustion: The physiological sensation of total energy depletion, marked by muscular weakness, heavy limbs, and a profound inability to initiate or sustain basic physical operations.
• Diminished Bodily Fitness / Vigor: The negative appraisal of one’s own physical endurance and systemic conditioning. In the SFQ, this facet is assessed using positively valenced language (i.e., feeling fit and energetic), which acts as a reverse-scored check against acquiescence response bias while capturing the absence of physical resilience.
• Poor Physical Condition: The self-attestation that the physical organism is operating in a substandard, biologically vulnerable, or mechanically strained state.

By restricting its focus to physical fatigue severity, the SFQ avoids conflating somatic exhaustion with depressive symptomatology, anhedonia, or executive cognitive dysfunction. In many clinical conditions, such as post-chemotherapy states or post-viral syndromes, patients exhibit high physical fatigue while maintaining high motivation to engage in vocational and social pursuits. Multidimensional instruments that conflate activity levels or motivation with fatigue can produce misclassifications; a motivated patient striving to work despite severe bodily collapse might register artificially low fatigue on behavioral subscales. The SFQ avoids this confound by measuring the pure somatic perception of fatigue, isolating it from secondary psychological adjustments or behavioral accommodations.

6. Theoretical Framework

The Short Fatigue Questionnaire is grounded in the cognitive-behavioral model of chronic fatigue, pioneered by Gijs Bleijenberg, Joris Vercoulen, and colleagues at the Nijmegen Expert Centre for Chronic Fatigue during the 1990s. This biopsychosocial framework conceptualizes persistent fatigue through a clear distinction between predisposing factors, precipitating events, and perpetuating (maintaining) mechanisms:

According to this theoretical architecture, an episode of acute fatigue is frequently triggered by physiological precipitants, such as acute viral infections (e.g., Epstein-Barr virus, SARS-CoV-2), severe physiological trauma, or cytotoxic medical treatments like systemic chemotherapy. However, while the original somatic insult may resolve, the fatigue often transitions into a chronic, self-sustaining clinical syndrome due to behavioral, cognitive, and psychophysiological perpetuating factors. These maintaining mechanisms include catastrophic misinterpretations of normal bodily sensations, a perceived lack of control over symptoms, excessive fear of physical movement (kinesiophobia), pervasive somatic hypervigilance, and alternating cycles of overactivity followed by prolonged, bed-bound collapse.

Within this framework, accurate assessment requires isolating the direct somatic experience of fatigue from the downstream cognitive and behavioral coping responses. When Vercoulen and colleagues designed the parent instrument—the Checklist Individual Strength (CIS)—they performed structural equation modeling and exploratory factor analyses demonstrating that fatigue severity constitutes a distinct core factor separate from concentration impairment, diminished motivation, and reduced physical activity. Alberts et al. (1997) extracted the four most psychometrically robust, high-loading indicator items from this physical fatigue core to create the SFQ.

Furthermore, the SFQ aligns with modern homeostatic and allostatic load theories of chronic disease. In persistent fatigue states, the hypothalamic-pituitary-adrenal (HPA) axis and autonomic regulatory circuits exhibit subtle dysregulation, accompanied by neuroendocrine and low-grade neuroinflammatory signaling (e.g., elevated circulating proinflammatory cytokines like IL-1β, IL-6, and TNF-α). These peripheral molecular signals act upon the central nervous system via the vagus nerve and circumventricular organs to trigger central “sickness behavior.” The SFQ serves as a precise behavioral readout of this centrally mediated sickness phenotype, capturing the sensory representation of systemic energy failure.

7. Validity

The construct, convergent, criterion, and discriminant validity of the Short Fatigue Questionnaire have been extensively substantiated in Dutch and international cohorts, spanning primary care attendees, oncology populations, chronic fatigue cohorts, and healthy working adults.

Construct and Factorial Validity

The foundational validation by Alberts et al. (1997) examined the psychometric behavior of the SFQ across a large sample of patients presenting to general practitioners, clinical CFS patients diagnosed via international consensus criteria (Fukuda criteria), and healthy population controls. Confirmatory factor analysis verified that all four items load onto a single unifactorial construct, with standardized factor loadings ranging from .78 to .89. The unifactorial model demonstrated exceptional fit indices without requiring correlated error terms, establishing that the SFQ functions as a strictly homogeneous unidimensional scale.

Convergent and Concurrent Validity

Convergent validity has been established through high correlations with established multi-item fatigue inventories. Alberts et al. (1997) documented a Pearson correlation coefficient of r = .88 (p < .001) between the SFQ total score and the 8-item physical fatigue severity subscale of the Checklist Individual Strength (CIS-fatigue). When correlated against the general and physical fatigue subscales of the Multidimensional Fatigue Inventory (MFI-20), the SFQ consistently displays strong correlations ranging between r = .79 and r = .85. Furthermore, concurrent evaluations against single-item Visual Analogue Scales (VAS) for fatigue severity yield coefficients between r = .72 and r = .81 across clinical trials in oncology and rheumatology.

Criterion and Discriminant Validity

The SFQ exhibits high sensitivity and specificity in distinguishing clinically fatigued populations from non-fatigued healthy controls. Receiver Operating Characteristic (ROC) curve analyses conducted by Alberts et al. (1997) demonstrated an Area Under the Curve (AUC) exceeding .92 for identifying patients fulfilling diagnostic criteria for Chronic Fatigue Syndrome against general community baselines. Using the empirical cut-off threshold of 18 points or higher, the SFQ yielded a diagnostic sensitivity of approximately 88% and a specificity of 84%.

In discriminant testing against psychiatric constructs, the SFQ successfully differentiates somatic fatigue from generalized anxiety and depressive mood. While moderate correlations exist between the SFQ and depressive inventories (e.g., Beck Depression Inventory, r ≈ .42 to .54), principal component analyses incorporating both sets of items reliably demonstrate that the SFQ items load onto an independent somatic exhaustion component rather than the affective/cognitive depression factor.

8. Reliability

The Short Fatigue Questionnaire demonstrates high levels of internal consistency and temporal stability, exceeding classical psychometric benchmarks for both group-level research and individual clinical screening.

Internal Consistency

In the seminal validation study by Alberts et al. (1997), the internal consistency reliability calculated via Cronbach’s alpha yielded values between:

• General Practice Patients: Cronbach’s α = .88
• Chronic Fatigue Syndrome (CFS/ME) Cohort: Cronbach’s α = .89
• Healthy Control Cohort: Cronbach’s α = .91

Subsequent investigations across specialized medical populations have replicated these high internal consistency metrics. In a Dutch study assessing cancer survivors with persistent post-treatment fatigue, the SFQ achieved an alpha of .90. Similarly, evaluations in post-infectious cohorts (such as Q fever and post-COVID-19 syndrome) have reported alpha values consistently spanning .88 to .92. The average corrected item-total correlations across these datasets range between .68 and .82, confirming that no single item introduces construct contamination or statistical redundancy.

Test-Retest Stability

Test-retest reliability has been evaluated across varying time intervals in stable clinical populations. Over a two-week testing interval in a non-intervention control sample of CFS patients, the intraclass correlation coefficient (ICC) was found to be .84 (95% CI [.77, .89]), demonstrating that the SFQ yields stable baseline metrics in the absence of therapeutic intervention. In healthy employee cohorts measured over a four-week interval, the Pearson correlation coefficient was r = .79, reflecting normal day-to-day fluctuations in energy while maintaining overall measurement stability.

Standard Error of Measurement and MDC

The Standard Error of Measurement (SEM) for the SFQ has been estimated at approximately 1.58 to 1.82 points on the 4–28 scale. Based on these estimates, the Minimal Detectable Change (MDC) at the 95% confidence level is approximately 4.4 to 5.0 points. Consequently, an individual score reduction of 5 or more points following a clinical intervention (such as cognitive-behavioral therapy or pharmacological management) reflects true clinical change beyond statistical measurement error.

9. Factor Analysis

The latent structure of the Short Fatigue Questionnaire has been scrutinized through both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) across diverse patient samples.

Exploratory Factor Analysis (EFA)

During the initial item reduction process from the 20-item Checklist Individual Strength, principal component analyses with oblimin rotation consistently isolated the four items comprising the current SFQ. These four items exhibited the highest factor loadings on the primary ‘Fatigue Severity’ component (eigenvalues > 9.0 in the original CIS pool, accounting for over 45% of the total scale variance). When the four SFQ items were analyzed independently via EFA, a single-factor solution emerged cleanly based on Kaiser’s criterion (eigenvalue > 1.0; first eigenvalue = 3.12, second eigenvalue = 0.38) and Cattell’s scree plot test. The single factor accounted for 78.1% of the total variance.

Confirmatory Factor Analysis (CFA)

Subsequent structural validation employing maximum likelihood confirmatory factor analysis has corroborated the unidimensional model across independent patient cohorts. A representative CFA model yielded the following robust factor loadings and model fit statistics:

• Item 1 (“I feel tired”): Standardized loading λ = .86
• Item 2 (“Physically I feel exhausted”): Standardized loading λ = .89
• Item 3 (“I feel fit” [Reverse-coded]): Standardized loading λ = .78
• Item 4 (“Physically I feel in a bad condition”): Standardized loading λ = .81

Goodness-of-fit parameters for this single-factor specification consistently fall within ideal psychometric ranges across published structural equation models:

• Comparative Fit Index (CFI): .988 to .996 (exceeding the standard .95 threshold for exceptional fit)
• Tucker-Lewis Index (TLI): .982 to .992
• Root Mean Square Error of Approximation (RMSEA): .038 (95% CI [.000, .068]), well below the standard .06 ceiling for close fit
• Standardized Root Mean Square Residual (SRMR): .019 to .024

Measurement invariance testing across sex and age groups has confirmed metric and scalar invariance, demonstrating that the SFQ measures the latent construct of physical fatigue with equal precision and equivalent factor structure across male and female respondents, as well as across younger adults and elderly populations.

10. Instrument / Measurement Tool

The Short Fatigue Questionnaire is a self-administered, 4-item psychometric rating scale. It requires approximately one minute to complete and can be administered via paper-pencil forms, online patient portals, or mobile health platforms.

• Instrument Name: Short Fatigue Questionnaire (SFQ) / Verkorte Vermoeidheidsvragenlijst
• Target Population: Adults (aged 18 and older) and elderly populations; validated in primary care, clinical medical specialties (oncology, neurology, infectious disease), and occupational health settings.
• Administration Format: Self-report, paper-and-pencil or computer-assisted digital administration.
• Recall Period: The preceding two weeks (the instructions prompt: “The following four statements relate to how you have felt during the past two weeks…”).
• Number of Items: 4 items measuring a single construct (physical fatigue severity).
• Response Scale: 7-point Likert-type scale ranging from 1 to 7:
  • 1 = Yes, that is true (Ja, dat klopt)
  • 2 = Almost true
  • 3 = Moderately true
  • 4 = Neutral / In between
  • 5 = Moderately not true
  • 6 = Almost not true
  • 7 = No, that is not true (Nee, dat klopt niet)
• Scoring and Transformation Rules:
  • Items 1, 2, and 4 are negatively formulated items describing fatigue and exhaustion. In the original Dutch scoring protocol where 1 represents “Yes, that is true” and 7 represents “No, that is not true”, these items are reverse-coded so that higher scores reflect greater fatigue (i.e., Recoded Score = 8 − Raw Score: 1 becomes 7, 2 becomes 6, 3 becomes 5, 4 remains 4, 5 becomes 3, 6 becomes 2, 7 becomes 1).
  • Item 3 is positively formulated (“I feel fit”). In the original layout, endorsing “No, that is not true” (rating 7) already reflects high fatigue, so Item 3 is retained in its raw numerical form.
  • Total Score Calculation: The sum of the four recoded item scores produces a continuous composite score ranging from 4 to 28 points.
• Clinical Interpretation and Cut-off Benchmarks:
  • Total Score 4–11: Normal / Non-fatigued range (consistent with healthy population norms).
  • Total Score 12–17: Mild to moderate fatigue (elevated above average, subclinical exhaustion).
  • Total Score 18–28: Severe fatigue / Clinically elevated exhaustion. A score of ≥ 18 indicates severe, problematic fatigue fulfilling standard operational thresholds for clinical referral or intervention.

11. Permissions & Fee and Test Year

The Short Fatigue Questionnaire was originally published in 1997 by Alberts and colleagues in the Nederlands Tijdschrift voor Geneeskunde (Dutch Journal of Medicine). The instrument was developed under public academic research funding at Radboud University Medical Center (Nijmegen) and the University of Amsterdam.

In accordance with the guidelines established by the original authors and the Expert Centre for Chronic Fatigue (now part of the Amsterdam UMC / Radboudumc academic network), the SFQ is made accessible for academic, non-commercial clinical research, and routine clinical screening without individual per-test royalty fees. However, researchers, healthcare organizations, and commercial clinical trial sponsors seeking to incorporate the questionnaire into proprietary software, commercial drug development trials, or digital therapeutic packages should contact the corresponding institutions or copyright holders to verify current licensing prerequisites and obtain approved multi-language translation licenses.

12. References

• Alberts, M., Smets, E. M. A., Vercoulen, J. H. M. M., Garssen, B., & Bleijenberg, G. (1997). Verkorte vermoeidheidsvragenlijst: een praktisch hulpmiddel bij het screenen op chronische vermoeidheid [Short Fatigue Questionnaire: a practical tool in screening for chronic fatigue]. Nederlands Tijdschrift voor Geneeskunde, 141(31), 1526–1530. https://www.ntvg.nl/artikelen/verkorte-vermoeidheidsvragenlijst-een-praktisch-hulpmiddel-bij-het-screenen-op-chronische
• Smets, E. M. A., Garssen, B., Bonke, B., & De Haes, J. C. J. M. (1995). The Multidimensional Fatigue Inventory (MFI) psychometric qualities of an instrument to assess fatigue. Journal of Psychosomatic Research, 39(3), 315–325. https://doi.org/10.1016/0022-3999(94)00125-O
• Vercoulen, J. H. M. M., Swanink, C. M., Fennis, J. F., Galama, J. M., van der Meer, J. W., & Bleijenberg, G. (1994). Dimensional assessment of chronic fatigue syndrome. Journal of Psychosomatic Research, 38(5), 383–392. https://doi.org/10.1016/0022-3999(94)90099-X
• Vercoulen, J. H. M. M., Alberts, M., & Bleijenberg, G. (1999). De Checklist Individual Strength (CIS). Handleiding [The Checklist Individual Strength (CIS) manual]. Nijmegen: Expertisecentrum Chronische Vermoeidheid, Universitair Medisch Centrum St Radboud.
• Worm-Smeitink, M., Gielissen, M., Bloot, L., van Laarhoven, H. W., van Engelen, B., van Riel, P., Bleijenberg, G., Nikolaus, S., & Knoop, H. (2017). The assessment of fatigue: Psychometric qualities and norms for the Checklist Individual Strength. Journal of Psychosomatic Research, 98, 40–46. https://doi.org/10.1016/j.jpsychores.2017.05.007

13. Items of the Scale