Oswestry Low Back Pain Disability Questionnaire

1. Abstract

The Oswestry Low Back Pain Disability Questionnaire, colloquially designated as the Oswestry Disability Index (ODI), represents the international gold-standard patient-reported outcome measure (PROM) for quantifying functional impairment and permanent disability in patients afflicted with mechanical, degenerative, and radicular spinal disorders. Originally published in 1980 by Jeremy C. T. Fairbank and colleagues at the Robert Jones and Agnes Hunt Orthopaedic Hospital in Oswestry, United Kingdom, the instrument was systematically formulated to evaluate how persistent low back pain impedes an individual’s capability to navigate fundamental activities of daily living (ADLs). The canonical scale comprises 10 self-administered domain sections: Pain Intensity, Personal Care, Lifting, Walking, Sitting, Standing, Sleeping, Sex Life, Social Life, and Travelling. Each domain provides six graded ordinal statements arranged in a Guttman-like hierarchy of increasing operational limitation, scored from 0 (no functional limitation or pain) to 5 (maximal functional limitation or pain). Total raw scores are normalized into a continuous percentage score ranging from 0% to 100%, segmented into five standardized categorical impairment tiers: minimal disability (0–20%), moderate disability (21–40%), severe disability (41–60%), crippling back pain (61–80%), and complete bed-bound state or symptom exaggeration (81–100%). Psychometric evaluations spanning more than four decades have demonstrated exemplary cross-sectional validity, high internal consistency (Cronbach’s alpha ranging from 0.71 to 0.90), robust test-retest reliability (intraclass correlation coefficients typically exceeding 0.85), and well-established minimal clinically important differences (MCID) ranging from 10 to 15 percentage points in surgical and conservative rehabilitation cohorts. The scale operates as an indispensable metric in spine surgery registries, randomized clinical trials, ergonomic assessments, and physical therapy monitoring worldwide.

2. Keywords

Oswestry Disability Index, ODI, low back pain, functional disability, patient-reported outcome measure, psychometrics, spine surgery, musculoskeletal rehabilitation, activities of daily living, minimal clinically important difference

3. Authors

The primary development and formal validation of the Oswestry Low Back Pain Disability Questionnaire were spearheaded by an interdisciplinary clinical team based at the Robert Jones and Agnes Hunt Orthopaedic Hospital in Oswestry, Shropshire, United Kingdom:

• Jeremy C. T. Fairbank, MD, FRCS — Emeritus Professor of Spine Surgery, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, and honorary consultant orthopaedic surgeon at the Nuffield Orthopaedic Centre, Oxford, UK.
• J. Couper, MCSP — Physiotherapist, Department of Physical Medicine and Rehabilitation, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK.
• J. B. Davies, MSc — Biostatistician and Research Methodologist, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK.
• John P. O’Brien, PhD, FRCS — Director of Spinal Disorders Service, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK.
• Paul B. Pynsent, PhD — Director of the Research and Teaching Centre, Royal Orthopaedic Hospital, Birmingham, UK (co-investigator and primary statistician for subsequent psychometric revisions and standardizations, notably the ODI Version 2.0 and 2.1a updates).

4. Purpose

The primary clinical and psychometric purpose of the Oswestry Low Back Pain Disability Questionnaire is to provide an objective, standardized, and patient-centered assessment of physical disability resulting from low back pain. In both clinical practice and empirical research, anatomical diagnostic measures—such as magnetic resonance imaging (MRI), computed tomography (CT), and plain radiography—frequently exhibit low correlation with a patient’s subjective pain experience, functional capacity, and day-to-day work limitations. The ODI was engineered to bridge the clinical gap between anatomical pathology and actual functional performance, quantifying the real-world impact of spinal symptoms on fundamental physical, domestic, professional, and leisure activities.

From an applied clinical perspective, the ODI serves three overarching functions: baseline severity stratification, clinical monitoring across treatment trajectories, and postoperative or post-rehabilitation outcome evaluation. Clinicians routinely deploy the ODI during initial patient intake to determine the precise threshold of disability, which directly informs clinical decision-making regarding conservative management (e.g., core stabilization, pharmacological analgesia, manual therapy) versus invasive interventions (such as epidural steroid injections, microdiscectomy, lumbar spinal fusion, or artificial disc arthroplasty). Furthermore, tracking longitudinal changes in ODI scores enables healthcare providers to evaluate treatment efficacy, detect treatment plateauing or symptom deterioration, and calculate compliance with institutional benchmarks for functional recovery.

In academic research, the questionnaire functions as a primary endpoint in clinical trials assessing pharmaceutical agents, surgical technologies, spinal cord stimulation, and chiropractic protocols. Because the ODI translates complex, heterogeneous clinical manifestations into a normalized 0–100% metric, it enables direct cross-study comparisons, meta-analyses, and health economics modeling, including Quality-Adjusted Life Year (QALY) estimations. Beyond standard orthopedics, the tool is extensively utilized in occupational health and medico-legal contexts to establish functional impairment baselines, verify disability benefit claims, and establish safe physical criteria for return-to-work protocols.

5. Psychological Construct

The core psychological and functional construct measured by the ODI is pain-related disability, defined as the degree to which an individual’s normal physical and social role functioning is constrained, disrupted, or prevented by lumbar spinal discomfort. Grounded in the intersection of health psychology and biomechanics, the questionnaire captures both objective behavioral restrictions and the subjective cognitive appraisals patients assign to their physical capacity in the presence of pain. The scale treats functional disability as a multidimensional phenomenon comprising ten interrelated behavioral domains:

• Pain Intensity: Evaluates the subjective sensory severity of spinal pain at the immediate moment of assessment, anchoring the physical limitations described in subsequent sections to current nociceptive or neuropathic discomfort.
• Personal Care (Washing, Dressing, etc.): Gauges autonomous execution of basic self-care activities of daily living. It measures the physical mechanics of spinal flexion, rotational flexibility, and prolonged balance during private hygienic routines.
• Lifting: Assesses axial spinal load-bearing capacity and the mechanical vulnerability of the posterior spinal column under external loading conditions, differentiating between unweighted spinal motion, lifting from elevated surfaces (e.g., tables), and lifting from ground level.
• Walking: Measures functional ambulation endurance, lower-limb neurogenic claudication, and radicular pain onset across explicit metric distance thresholds (ranging from unrestricted distances down to 100 yards, reliance on assistive devices, or complete bed confinement).
• Sitting: Measures static lumbar postural endurance and disc pressure tolerance, charting the patient’s capacity to maintain an upright or supported seated posture before mechanical pain forces a postural transition.
• Standing: Reflects tolerance for static vertical axial loading and lumbar facet joint articulation, quantifying time-delimited thresholds ranging from unrestrained standing to severe temporal restrictions under 10 minutes.
• Sleeping: Explores nocturnal pain intrusion, sleep architecture disruption, and nighttime postural recumbency, reflecting severe inflammatory or structural mechanical disruption that overcomes physiological rest.
• Sex Life: Investigates intimate physical activity and pelvic/lumbar mechanical tolerance during sexual intercourse. This section represents a critical, often stigmatized psychosocial domain that is highly susceptible to pain-related avoidance behavior and relational strain.
• Social Life: Quantifies the patient’s integration into community, recreational, and interpersonal settings. It traces the progression of functional withdrawal from high-energy activities (e.g., athletics) down to total domestic confinement and complete social isolation.
• Travelling: Assesses the combined biomechanical stressors of whole-body vibration, spatial confinement, and forced sedentary positioning encountered during vehicular transit over varying temporal durations.

These domains collectively represent the cognitive-behavioral manifestation of the pain experience: how nociception transforms into operational avoidance, functional decrement, and systemic disruption of personal identity and autonomy.

6. Theoretical Framework

The structural design and conceptualization of the Oswestry Low Back Pain Disability Questionnaire are anchored in early medical sociology and contemporary health psychology models, notably the Biopsychosocial Model of Illness formulated by George Engel (1977), the International Classification of Impairments, Disabilities, and Handicaps (ICIDH) originally proposed by the World Health Organization (WHO), and its modern evolution, the International Classification of Functioning, Disability and Health (ICF).

Traditional biomedical paradigms assumed a linear, deterministic relationship between anatomical spinal pathology (e.g., lumbar disc herniation, facet arthrosis, spondylolisthesis) and experienced functional limitation. However, Fairbank and colleagues recognized that structural abnormalities identified through clinical examination or imaging frequently failed to account for the broad variance observed in patient disability. Consequently, the ODI was developed on the theoretical premise that disability is not an intrinsic physical trait, but rather an emergent, multidimensional behavioral construct resulting from continuous interactions between physiological tissue stress, cognitive-affective processing, and socio-environmental demands.

Under the ICF framework, the ODI operates primarily across the operational domains of Activities (execution of specific tasks such as lifting, walking, and sitting) and Participation (involvement in life situations such as occupational traveling, maintaining a social life, and engaging in sexual intimacy). The instrument operationalizes Saad Nagi’s Disablement Model (1965), which distinguishes between four sequential concepts:

1. Active Pathology: Cellular or structural disruption of the spine.
2. Impairment: Specific physiological or anatomical loss (e.g., restricted lumbar range of motion, muscle spasm).
3. Functional Limitation: Restrictions in individual performance of basic physical actions (e.g., inability to stand for 30 minutes, inability to lift 10 kilograms).
4. Disability: Inability to perform socially defined roles and tasks within a specific sociocultural context (e.g., cessation of employment, cessation of social engagement).

Furthermore, the questionnaire interfaces deeply with the Fear-Avoidance Model of Musculoskeletal Pain (Vlaeyen & Linton, 2000). The Guttman-like hierarchical response structure across the 10 domains reflects how catastrophic cognitive appraisals of pain generate kinesiophobia (fear of movement), driving hypervigilance, protective guarding, progressive avoidance of physical activity, and secondary physical deconditioning. By systematically capturing these graded behavioral avoidances, the ODI provides an operational measure of the degree to which fear-avoidance cycles have consolidated into generalized daily functional impairment.

7. Validity

The psychometric validity of the Oswestry Disability Index has been scrutinized across hundreds of independent empirical investigations worldwide, consistently establishing the instrument as a robust, methodologically sound index of spinal-related impairment.

Construct and Convergent Validity

Construct validity has been repeatedly substantiated through high convergent correlations with other validated spinal-specific and generic health status instruments. Strong positive correlations are systematically observed between the ODI and the Roland-Morris Disability Questionnaire (RMDQ), with Pearson’s r and Spearman’s rho coefficients consistently ranging between 0.70 and 0.85 across mixed populations of acute and chronic low back pain patients (Fritz & Irrgang, 2001; Davidson & Keating, 2002). When benchmarked against visual analogue scales (VAS) and numeric rating scales (NRS) for back and leg pain, the ODI demonstrates moderate-to-strong positive correlations (typically r = 0.60 to 0.75), confirming that while functional limitation is inherently driven by nociception, it captures unique variance unmeasured by pain intensity alone.

Furthermore, convergent validity is evidenced by significant negative correlations with the physical health domains of generic health status questionnaires. In studies comparing the ODI against the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), the ODI exhibits pronounced inverse correlations with the Physical Functioning subscale (r = -0.65 to -0.82) and the Physical Component Summary (PCS) score (r = -0.60 to -0.78), demonstrating that higher disability on the ODI accurately mirrors reduced functional physical vitality (Fairbank & Pynsent, 2000).

Discriminant and Known-Groups Validity

The instrument exhibits discriminant validity by demonstrating noticeably weaker correlations with divergent psychological dimensions. Correlations between the ODI total percentage score and the Mental Health, Emotional Role Functioning, and General Mental Component Summary (MCS) subscales of the SF-36 typically range from weak to low-moderate (r = -0.25 to -0.40). This divergence confirms that the instrument specifically evaluates physical and operational disability rather than generalized affective distress or generic psychological morbidity.

Known-groups validity has been demonstrated by the questionnaire’s ability to discriminate between distinct patient populations possessing varying degrees of verified anatomical or occupational impairment. The ODI differentiates with high statistical significance (p < 0.001) between patients working full-time without medical leave, individuals on light or restricted work duties, patients receiving chronic workers’ compensation, and surgical candidates listed for spinal fusion or decompressive laminectomy.

Predictive Validity and Responsiveness (MCID)

The responsiveness of the ODI to meaningful clinical improvement has made it the primary metric for defining successful surgical and non-surgical outcomes. Multiple receiver operating characteristic (ROC) curve analyses have established the Minimal Clinically Important Difference (MCID) of the ODI:

• In surgical cohorts undergoing lumbar spine fusion or arthroplasty, the widely accepted threshold for meaningful clinical improvement is a reduction of 10 to 12.8 percentage points (or a 30% relative improvement from baseline) (Copay et al., 2008).
• In conservative physical therapy and non-operative rehabilitation settings, an MCID threshold of 10 points is generally accepted as reflecting a true, noticeable clinical recovery beyond measurement error (Ostelo et al., 2008).

8. Reliability

The reliability of the Oswestry Low Back Pain Disability Questionnaire has been exhaustively documented across diverse geographical, clinical, and linguistic contexts, demonstrating exceptional internal consistency, stability over time, and minimal measurement error.

Internal Consistency

Internal consistency analyses evaluate the degree to which all ten domain sections measure the same fundamental construct of pain-induced disability. Across validation literature spanning community clinics, tertiary orthopedic centers, and multinational surgical registries, Cronbach’s alpha (α) for the ODI consistently ranges from 0.71 to 0.90:

• Fairbank & Pynsent (2000) synthesized multiple clinical iterations, reporting Cronbach’s alpha values typically stabilizing between 0.76 and 0.87, indicating excellent item coherence without redundant duplication.
• Fritz & Irrgang (2001) reported an alpha coefficient of 0.87 in an outpatient orthopedic physical therapy population, demonstrating robust internal consistency across heterogeneous acute and subacute spinal presentations.
• Cross-cultural adaptations (including German, Spanish, French, Japanese, and Arabic versions) systematically confirm alpha values within the optimal psychometric target window of 0.80 to 0.92, verifying cross-linguistic structural integrity.

Test-Retest Reliability

The temporal stability of the ODI has been tested across varying test-retest intervals ranging from 24 hours to four weeks in clinically stable patient cohorts. In the initial validation trials by Fairbank et al. (1980), patients tested on consecutive days showed a high test-retest correlation coefficient (r = 0.99). Subsequent rigorous investigations utilizing intraclass correlation coefficients (ICC, two-way random-effects model) have supported these findings:

• Over short retest intervals (24 to 48 hours), ICC values typically range between 0.88 and 0.99 (Baker et al., 1989; Davidson & Keating, 2002).
• Over intermediate intervals (7 to 14 days) in chronic populations exhibiting no change in clinical status, ICC values remain exceptionally high, consistently stabilizing between 0.83 and 0.94.

Measurement Precision: SEM and MDC

To differentiate true biological and functional clinical improvement from underlying measurement noise, psychometricians have established strict threshold values for the Standard Error of Measurement (SEM) and the Minimal Detectable Change (MDC):

• Standard Error of Measurement (SEM): Literature estimates place the SEM of the ODI at approximately 3.54 to 4.50 percentage points.
• Minimal Detectable Change (MDC at 95% confidence): The MDC₉₅ (calculated as $SEM \times 1.96 \times \sqrt{2}$) ranges between 9.8 and 12.0 percentage points. This statistical benchmark establishes that any individual score change exceeding 10–12 points can be classified with 95% statistical confidence as a genuine functional shift rather than random instrument noise or daily biological fluctuation.

9. Factor Analysis

The underlying latent dimensional structure of the Oswestry Disability Index has been a subject of extensive empirical inquiry using both Exploratory Factor Analysis (EFA), Confirmatory Factor Analysis (CFA), and Modern Test Theory paradigms such as Rasch Item Response Modeling.

Unidimensional vs. Multidimensional Factor Solutions

Although the ODI is primarily administered and scored as a unidimensional composite index yielding a single total disability percentage, factor analytic studies across international samples have presented nuanced structural configurations:

• Unidimensional Model: Proponents of the single-factor model argue that all 10 items load significantly onto an overarching latent factor representing general spinal disability. Studies utilizing strict unidimensional criteria frequently identify that the first unrotated eigenvalue accounts for 45% to 60% of the total variance, meeting standard psychometric thresholds for essential unidimensionality (Fairbank & Pynsent, 2000).
• Two-Factor Orthogonal/Oblique Models: Multiple EFAs have revealed a stable two-factor structure (accounting for 55% to 68% of cumulative variance):
• Factor 1: Dynamic Physical Activities / Mechanical Loading — Typically includes Section 2 (Personal Care), Section 3 (Lifting), Section 4 (Walking), Section 5 (Sitting), and Section 6 (Standing). Item loadings on this dynamic biomechanical factor commonly range between 0.65 and 0.88.
• Factor 2: Static / Psychosocial and Sedentary Interference — Encompasses Section 1 (Pain Intensity), Section 7 (Sleeping), Section 8 (Sex Life), Section 9 (Social Life), and Section 10 (Travelling). Item loadings on this psychosocial and rest-related factor typically range between 0.55 and 0.82.
• Three-Factor Models: Other investigations, particularly in severe chronic pain or preoperative surgical cohorts, describe a three-factor solution:
• Factor A (Physical Activities): Personal Care, Lifting, Walking.
• Factor B (Postural Endurance): Sitting, Standing, Travelling.
• Factor C (Pain and Rest Disruption): Pain Intensity, Sleeping, Social Life, Sex Life.

Confirmatory Factor Analysis (CFA) Fit Indices

When evaluated via Confirmatory Factor Analysis, structural equation modeling typically yields acceptable-to-excellent fit indices for both the unified single-factor model (when correlated error terms between clinically linked items such as sitting and standing are specified) and the hierarchical two-factor model:

• Comparative Fit Index (CFI): Typically exceeds 0.93 to 0.96.
• Tucker-Lewis Index (TLI): Consistently reported between 0.91 and 0.95.
• Root Mean Square Error of Approximation (RMSEA): Generally ranges from 0.045 to 0.070, falling well within accepted standards for acceptable model fit.

Rasch Analysis and Modern Test Theory Insights

Application of the Rasch Rating Scale Model has provided critical insights into item hierarchy, category functioning, and item fit statistics (Infit and Outfit mean squares):

• Item Difficulty Hierarchy: Rasch calibration demonstrates that the ODI items span a wide continuum of disability severity. Section 3 (Lifting) and Section 6 (Standing) systematically emerge as the “easiest” items (endorsed at high limitation levels even by patients with minimal overall impairment), whereas Section 4 (Walking) and Section 2 (Personal Care) represent the “most difficult” items (requiring severe, crippling pathology before higher response categories are endorsed).
• Item Fit: The majority of items demonstrate adequate fit to the latent Rasch continuum, with Infit and Outfit Mean Square (MnSq) statistics falling within the desired 0.70 to 1.30 range. Section 8 (Sex Life) occasionally displays minor underfit or elevated missing response rates due to cultural sensitivities, which prompted the formulation of modified scoring algorithms that handle missing items without distorting the final metric.

10. Instrument / Measurement Tool

Instrument Specifications

• Instrument Name: Oswestry Low Back Pain Disability Questionnaire (also known as the Oswestry Disability Index, ODI).
• Primary Author: Jeremy C. T. Fairbank (1980; revisions with Paul B. Pynsent, 2000).
• Administration Method: Paper-and-pencil questionnaire, computerized adaptive or web-based survey, or clinician-assisted interview.
• Target Population: Adult and adolescent patients (ages 16+) presenting with acute, subacute, or chronic low back pain, radiculopathy, spinal stenosis, spondylolisthesis, or post-surgical spinal conditions.
• Completion Time: Approximately 3.5 to 5 minutes.
• Item Count: 10 distinct domain sections.
• Response Format: 6-point Guttman-like scale per section, scored 0 to 5 points (0 = least disability / no pain, 5 = most severe disability / maximum pain).

Mathematical Scoring Methodology

The scoring procedure for the ODI converts ordinal categorical selections into a standardized percentage metric, accommodating instances where individual sections are omitted (e.g., if Section 8 on Sex Life is left blank or deemed non-applicable):

1. Each of the 10 sections contains six operational statements. The statements are scored hierarchically from top to bottom on an integer scale ranging from 0 (first statement, denoting zero functional limitation) to 5 (sixth statement, denoting maximum functional limitation).
2. The raw scores of all successfully completed sections are summed to determine the Raw Score Sum:

$$\text{Raw Score Sum} = \sum_{i=1}^{k} \text{Item Score}_i$$

3. The Total Possible Score is calculated by multiplying the total number of answered sections ($k$) by 5:

$$\text{Total Possible Score} = k \times 5$$

If all 10 sections are answered, $k = 10$, making the Total Possible Score equal to 50. If one section (such as Sex Life) is omitted, $k = 9$, making the Total Possible Score equal to 45.

4. The final normalized percentage score is determined by the following formula:

$$\text{ODI Percentage Score (%)} = \left( \frac{\text{Raw Score Sum}}{k \times 5} \right) \times 100$$

Clinical Severity Stratification

The resulting percentage score is categorized into one of five validated clinical severity bands:

• 0% to 20% — Minimal Disability: The patient can cope with most activities of daily living. No formal medical treatment is indicated apart from advice on lifting, physical fitness, posture, and ergonomic preservation. Many individuals in this category manage their symptoms without significant professional intervention.
• 21% to 40% — Moderate Disability: The patient experiences more severe pain and difficulty with sitting, lifting, and standing. Travel and social life become significantly more challenging. Personal care and sleeping are typically maintained with modifications. Management usually centers on conservative rehabilitation, physical therapy, and ergonomic adjustments.
• 41% to 60% — Severe Disability: Pain remains the dominant problem in the patient’s life, significantly impacting basic daily activities. Travel, social interaction, personal care, and sleep are severely compromised. Detailed spinal diagnostic workups, multidisciplinary rehabilitation programs, and surgical consultations are frequently indicated.
• 61% to 80% — Crippling Back Pain: Back pain severely impinges on all aspects of the patient’s daily life. Active social interventions are curtailed. The individual is incapable of independent living without extensive assistance or substantial environmental modifications. Surgical decompression or stabilization is often actively explored if structural indications exist.
• 81% to 100% — Bed-Bound or Symptom Exaggeration: Patients in this extreme tier are either completely bed-bound and dependent on full-time caregiving for basic physiological needs, or they are demonstrating significant symptom magnification, non-organic behavioral signs, or severe psychological distress requiring urgent psychiatric or chronic pain behavioral intervention.

11. Permissions & Fee and Test Year

The Oswestry Low Back Pain Disability Questionnaire was originally published in 1980 in the journal Physiotherapy. Over the subsequent decades, the questionnaire underwent minor linguistic refinements, resulting in Version 2.0 (developed by the Medical Research Council group in the UK) and Version 2.1a.

Copyright and Licensing Administration:

• The original copyright in the Oswestry Disability Index is retained by Jeremy C. T. Fairbank and the Robert Jones and Agnes Hunt Orthopaedic Hospital.
• The global licensing, distribution, and linguistic translation rights are managed by Mapi Research Trust through their PROVIDE database platform (https://eprovide.mapi-trust.org).
• Academic and Non-Commercial Use: The ODI is accessible free of charge for individual clinical practice, non-funded academic research, individual healthcare professionals, and charitable non-profit educational activities, provided that proper formal citation is attributed to the original 1980 publication and no modifications are introduced to the wording or scoring mechanics.
• Commercial and Funded Clinical Trials: For pharmaceutical companies, medical device manufacturers, contract research organizations (CROs), commercial clinical trials, and proprietary digital health/software applications, formal licensing approval and the payment of copyright royalty fees are required through Mapi Research Trust.

12. References

• Baker, D. J., Pynsent, P. B., & Fairbank, J. C. T. (1989). The Oswestry Disability Index revisited: Its reliability, repeatability and validity, and a comparison with the St. Thomas’s Disability Index. In M. O. Roland & J. R. Jenner (Eds.), Back pain: New approaches to rehabilitation and education (pp. 174–186). Manchester University Press.
• Copay, A. G., Glassman, S. D., Subach, B. R., Berven, S., Schuler, T. C., & Carreon, L. Y. (2008). Minimum clinically important difference in lumbar spine surgery patients: A choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form-36, and pain scales. The Spine Journal, 8(6), 968–974. https://doi.org/10.1016/j.spinee.2007.11.006
• Davidson, M., & Keating, J. L. (2002). A comparison of five low back disability questionnaires: Reliability and responsiveness. Physical Therapy, 82(1), 8–24. https://doi.org/10.1093/ptj/82.1.8
• Engel, G. L. (1977). The need for a new medical model: A challenge for biomedicine. Science, 196(4286), 129–136. https://doi.org/10.1126/science.847460
• Fairbank, J. C. T., Couper, J., Davies, J. B., & O’Brien, J. P. (1980). The Oswestry Low Back Pain Disability Questionnaire. Physiotherapy, 66(8), 271–273.
• Fairbank, J. C. T., & Pynsent, P. B. (2000). The Oswestry Disability Index. Spine, 25(22), 2940–2953. https://doi.org/10.1097/00007632-200011150-00017
• Fritz, J. M., & Irrgang, J. J. (2001). A comparison of a modified Oswestry Low Back Pain Disability Questionnaire and the Quebec Back Pain Disability Scale. Physical Therapy, 81(2), 776–788. https://doi.org/10.1093/ptj/81.2.776
• McDowell, I. (2006). Measuring health: A guide to rating scales and questionnaires (3rd ed.). Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195165678.001.0001
• Nagi, S. Z. (1965). Some conceptual issues in disability and rehabilitation. In M. B. Sussman (Ed.), Sociology and rehabilitation (pp. 100–113). American Sociological Association.
• Ostelo, R. W., Deyo, R. A., Stratford, P., Waddell, G., Croft, P., Von Korff, M., Bouter, L. M., & de Vet, H. C. (2008). Interpreting change scores for pain and functional status in low back pain: Towards international consensus regarding minimal important change. Spine, 33(1), 90–94. https://doi.org/10.1097/BRS.0b013e31815e3a10
• Roland, M., & Morris, R. (1983). A study of the natural history of back pain: Part I: Development of a reliable and sensitive measure of disability in low-back pain. Spine, 8(2), 141–144. https://doi.org/10.1097/00007632-198303000-00004
• Smeets, R., Köke, A., Lin, C. W., Ferreira, M., & Demoulin, C. (2011). Measures of function in low back pain/disorders. Arthritis Care & Research, 63(S11), S158–S173. https://doi.org/10.1002/acr.20542
• Torenbeek, M., Caulfield, B., Garrett, M., et al. (2001). Current use of outcome measures for stroke and low back pain rehabilitation in five European countries: First results of the ACROSS project. International Journal of Rehabilitation Research, 24(2), 95–101. https://doi.org/10.1097/00004356-200106000-00002
• Vlaeyen, J. W., & Linton, S. J. (2000). Fear-avoidance and its consequences in chronic musculoskeletal pain: A state of the art. Pain, 85(3), 317–332. https://doi.org/10.1016/S0304-3959(99)00242-0
• World Health Organization. (2001). International classification of functioning, disability and health: ICF. World Health Organization.

13. Items of the Scale (Questionnaire)