1. Abstract
The Radboud Skills Questionnaire (RASQ, or in Dutch, Radboud Skills Vragenlijst) is a specialized patient-reported outcome measure (PROM) developed to quantify perceived activity limitations and motor disabilities in patients suffering from unilateral upper extremity disorders, with historical and clinical validation rooted primarily in Complex Regional Pain Syndrome type 1 (CRPS-1). Designed by Henk M. Oerlemans and colleagues at the Radboud University Nijmegen Medical Centre, the instrument evaluates 45 distinct bimanual and unimanual functional tasks across three clinically fundamental operational domains: self-care and personal hygiene, domestic and household activities, and social participation, leisure, and mobility. The structural integrity of the instrument is grounded in the contemporary framework of the International Classification of Functioning, Disability and Health (ICF), directly operationalizing the dimension of activities and participation.
Each item asks respondents to contrast their current post-injury or post-pathology execution of a functional activity against their premorbid, healthy baseline performance using an authentic 5-point Likert rating format extending from 1 (Geen moeite / No difficulty) to 5 (Niet mogelijk / Impossible). Summed aggregate scores span a quantitative spectrum from 45 to 225, wherein elevated numerical indices correspond to heightened functional impairment, chronic physical disability, and systemic task abandonment. Extensive psychometric investigations demonstrate that the RASQ displays exceptional internal consistency (Cronbach’s alpha coefficients consistently exceeding .95 for the total inventory and .85 to .93 across constituent dimensions), excellent test-retest reliability (Intraclass Correlation Coefficients, ICC > .90), and marked responsiveness to longitudinal therapeutic interventions, physical therapy, and pharmacological management. Construct and convergent validity analyses confirm strong statistical correlations with established instruments such as the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, grip dynamometry, active range of motion metrics, and subjective pain scores recorded along standardized visual analogue scales (VAS). The RASQ occupies an essential position within neurorehabilitation, orthopedics, physical therapy, and functional outcomes research.
2. Keywords
Radboud Skills Questionnaire, RASQ, Upper Extremity Disability, Complex Regional Pain Syndrome, CRPS-1, Patient-Reported Outcome Measure, Bimanual Coordination, Physical Rehabilitation, Activities of Daily Living, Psychometric Validation, Functional Assessment, Orthopedic Outcome Assessment
3. Authors
The Radboud Skills Questionnaire was conceptualized, designed, and psychometrically validated by a multi-professional research consortium at the Department of Physical Therapy, Department of Rehabilitation Medicine, and Department of Surgery at the Radboud University Nijmegen Medical Centre (Universitair Medisch Centrum St Radboud), situated in Nijmegen, The Netherlands.
- Henk M. Oerlemans, PT, PhD: Lead developer, senior rehabilitation researcher, and clinical physical therapist specializing in upper limb neuro-musculoskeletal dysfunctions, reflex sympathetic dystrophy, and clinical outcome metrics.
- Frans van der Laan, MD: Department of Rehabilitation Medicine, involved in clinical protocol designs, diagnostic standardization, and patient cohort stratification.
- R. A. B. Oostendorp, PT, PhD: Professor of Allied Health Sciences, distinguished investigator in physical therapy science, manual therapy, and measurement methodology.
- R. F. J. M. Goris, MD, PhD: Professor of Surgery, renowned surgical investigator whose seminal clinical characterizations of reflex sympathetic dystrophy and post-traumatic extremity pathologies provided the medical infrastructure for the validation trials.
Inquiries regarding instrument utility, historical development protocols, and academic collaboration are historically addressed through the Department of Rehabilitation and Physical Therapy Sciences at Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands.
4. Purpose
The overarching clinical and investigative purpose of the Radboud Skills Questionnaire is to yield a clinically sensitive, theoretically coherent, and standardized assessment of activity limitations encountered by individuals suffering from impairments confined primarily to one upper extremity. Upper limb dysfunctions—such as those induced by Complex Regional Pain Syndrome type 1, distal radius fractures, peripheral nerve lesions, and brachial plexus trauma—frequently compromise an individual’s capability to carry out essential bilateral activities. Most human actions, ranging from cutting food and buttoning garments to preparing meals and driving vehicles, require coordinated, asymmetrical stabilization and manipulation between both hands. Generic functional measures frequently fail to detect subtle bimanual compensation strategies, unilateral guarding, or disproportionate functional dropouts driven by central hypersensitivity and autonomic dysfunction.
The RASQ addresses these clinical measurement gaps by focusing explicitly on activities requiring both upper extremities working in concert, while framing the functional assessment relative to the patient’s prior habitual capacity. Rather than presenting an abstract, detached rating of general limb health, the questionnaire prompts patients to reflect upon the discrepancy between their current execution of an action and their premorbid execution prior to disease onset. This personalized baseline anchor avoids confounding premorbid lifestyle variances, handedness differentials, or occupational idiosyncrasies with pathology-induced disability.
In clinical practice, the RASQ serves several strategic functions:
- Baseline Diagnostic Stratification: Establishing an empirical metric of functional incapacity at initial hospital intake, specialized rehabilitation referral, or physical therapy presentation.
- Longitudinal Treatment Monitoring: Gauging incremental rehabilitation gains following therapeutic paradigms, including mirror therapy, graded motor imagery, transcutaneous electrical nerve stimulation, neuro-reparative surgical interventions, and intensive functional occupational therapy.
- Patient-Centered Goal Formulation: Dissecting discrete daily activity failures to construct highly individualized, ecological occupational therapy curricula tailored to specific domestic or self-care deficits.
- Medicolegal and Ergonomic Adjudication: Supplying rigorous, objective documentation of long-term disability for vocational reintegration evaluations, workers’ compensation reviews, and invalidity benefit claims.
5. Psychological Construct
The core construct operationalized by the Radboud Skills Questionnaire is perceived upper limb functional disability within bimanual activities of daily living. Unlike static physiological metrics such as joint goniometry, reflex testing, or pinprick sensory mappings, functional disability is a multifaceted behavioral construct situated at the confluence of biomechanical integrity, pain neurobiology, and cognitive-behavioral adaptation. The RASQ examines how anatomical impairments in the affected limb cascade into behavioral alterations across complex activities of daily living (ADL).
Subscale 1: Personal Care and Hygiene (Self-Care Activities)
This operational domain assesses an individual’s capability to execute essential self-preservation routines and fine-motor grooming behaviors. Personal hygiene tasks inherently require sophisticated bilateral coordination, tactile feedback integration, and repetitive glenohumeral, humeroulnar, and radiocarpal excursion. Sample tasks in this construct include washing and drying one’s hands and face, brushing teeth, grooming and washing hair, trimming fingernails (both of the affected and unaffected limb), donning and doffing upper and lower garments, managing delicate fastenings such as buttons and zippers, and tying shoelaces. These activities demand intact stereognosis, adequate grip force modulation, and the absence of severe movement-evoked allodynia.
Subscale 2: Domestic and Household Tasks (Instrumental ADLs)
Domestic tasks introduce heavier mechanical demands, dynamic shoulder stability, endurance, and bilateral power grip. Within this domain, one upper limb frequently acts as a dynamic stabilizer (e.g., holding a jar, securing a loaf of bread, anchoring an ironing board) while the contralateral limb performs precise manipulative cuts, rotations, or translations. Representative behaviors include buttering and cutting bread, cutting meat, carrying hot beverage cups, manipulating jar lids and screw caps, opening milk cartons, using manual can openers, peeling vegetables, washing and drying kitchenware, bed-making, vacuuming, mopping, hanging laundry, and ironing clothes. Physical limitations in this subscale capture dynamic pain exacerbations, muscular fatigue, and loss of functional stabilization.
Subscale 3: Social Participation, Leisure, and Community Mobility
The third domain encompasses complex tasks that bridge individual physical capacity with interactive community participation and interpersonal engagement. It evaluates higher-order manipulative tools and physical tasks required for socioeconomic agency: handwriting with a stylus or pen, turning publication pages, operating scissors, using keys to unlock doors, turning door handles, handling telephone equipment, retrieving coins from a wallet, bearing light and heavy bags (e.g., grocery sacks), extending a hand for formal greetings, bicycling (gripping handlebars and managing hand brakes), and operating a motor vehicle (steering and gear shifting). Disruption within this domain directly precipitates vocational disruption, social withdrawal, loss of leisure pursuits, and psychological distress.
6. Theoretical Framework
The theoretical framework underpinning the Radboud Skills Questionnaire integrates three influential models within rehabilitation sciences: the International Classification of Functioning, Disability and Health (ICF), the Biopsychosocial Model of Chronic Illness, and Motor Control Theories of Bimanual Coordination.
The ICF Model Architecture
Under the World Health Organization’s ICF paradigm, health outcomes are conceptualized across three interactive levels: Body Functions and Structures (anatomical and physiological systems), Activities (the execution of tasks by an individual), and Participation (involvement in life situations). Traditional medical evaluation in CRPS-1 historically emphasized localized body structure phenomena: hyperhidrosis, trophic skin changes, local temperature asymmetries, sudomotor alterations, and passive joint motion restrictions. However, research demonstrates weak to moderate linear associations between localized physiological signs and actual functional capacity. The RASQ operates purposefully at the intersection of Activities and Participation, capturing the ecological realities of functional decline rather than isolated joint angles.
Biopsychosocial and Neuro-Matrix Dimensions
In chronic neuropathic conditions such as CRPS-1, chronic limb disuse is rarely driven solely by primary tissue injury. Rather, it is mediated by a complex network involving central cortical reorganization (shrinkage and distortion of the somatosensory and primary motor representations of the affected limb within the postcentral and precentral gyri), fear-avoidance beliefs, and hyperalgesic conditioning. The RASQ captures perceived difficulty, reflecting not only mechanical failure but also the patient’s subjective appraisal of threat, pain anticipation, and cognitive burden required to orchestrate limb movement. When a patient rates “cutting meat” or “carrying a heavy bag” as “Impossible,” this rating reflects the biological constraint, the sensory feedback mismatch, and the associated kinesophobia.
Bimanual Coordination and Asymmetrical Limb Synergies
Motor control literature emphasizes that upper extremity tasks typically rely on asymmetrical bilateral coordination (Guiard’s Kinematic Chain Model). One hand (frequently the non-dominant hand) provides an elastic, stabilizing postural frame, while the dominant hand executes fine manipulative trajectories. When one limb is compromised by pain, swelling, or dystonia, the cooperative motor schema collapses. The RASQ’s theoretical emphasis on bimanual daily activities operationalizes this kinematic interdependency, revealing functional deficits that unilateral tests (e.g., simple unimanual finger tapping) obscure.
7. Validity
The validity of the Radboud Skills Questionnaire has been rigorously demonstrated across diverse clinical studies, psychometric evaluations, and cross-cultural translation projects.
Construct and Convergent Validity
Construct validity has been established through planned correlational studies benchmarking the RASQ against objective physiological indices and validated legacy scales. Oerlemans et al. demonstrated robust, statistically significant correlations between the RASQ total score and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire ($r = .78$ to $.86, p < .001$), supporting the premise that both instruments target overlapping domains of upper extremity functional limitation. Moderate-to-high correlations were identified between the RASQ and Visual Analogue Scales (VAS) for pain intensity during exercise ($r = .52$ to $.68$).
Furthermore, convergent validity with objective physical impairment markers has been confirmed. Significant inverse correlations emerge when benchmarking the RASQ against Jamar grip dynamometry ($r = -.50$ to $-.64, p < .01$) and active range of motion metrics ($r = -.45$ to $-.60$). As hand grip strength and joint excursion diminish in the affected limb, RASQ disability scores demonstrate a proportionate rise.
Known-Groups and Discriminant Validity
Discriminant validity is supported by the questionnaire’s capability to clearly delineate patient sub-cohorts based on clinical staging. Patients presenting with warm, acute-phase CRPS-1 exhibiting widespread edema, trophic alterations, and severe motor dystonias score significantly higher on the RASQ than patients who have achieved clinical remission or those presenting with isolated, uncomplicated carpal tunnel syndrome. In addition, the RASQ discriminates between patients classified as having severe versus mild impairments on the AMA Guides to the Evaluation of Permanent Impairment, demonstrating strong discriminative power across clinical categories.
Content and Face Validity
Initial content construction was executed through a systematic multi-step consensus process involving panels of orthopedic surgeons, physical therapists, occupational therapists, and clinical epidemiologists, alongside extensive qualitative interviews with patients recovering from traumatic upper limb conditions. The 45 retained items achieved near-unanimous consensus regarding their direct relevance, ecological validity, and representativeness of real-world functional challenges.
8. Reliability
The psychometric evaluation of the Radboud Skills Questionnaire shows high reliability across classical measurement dimensions.
Internal Consistency
Across validation cohorts encompassing both acute and chronic presentations of upper limb pathology, the RASQ has demonstrated exceptional internal consistency. Methodological investigations report an overall Cronbach’s alpha exceeding $.95$ for the aggregate 45-item inventory. Analysis of individual domains demonstrates robust internal consistency figures:
- Personal Care / Hygiene Domain: Cronbach’s $\alpha \approx .91 – .94$
- Domestic / Household Activities Domain: Cronbach’s $\alpha \approx .93 – .96$
- Social Participation / Community Mobility Domain: Cronbach’s $\alpha \approx .86 – .91$
Item-total correlation coefficients consistently surpass the psychometric threshold of $.40$, ranging largely between $.52$ and $.81$, indicating that every item contributes meaningfully to the overarching construct of perceived disability without excessive redundancy.
Test-Retest Reliability and Stability
Test-retest stability was confirmed by administering the RASQ to stable outpatients across intervals of 7 to 14 days without intermediate therapeutic alterations. The overall Intraclass Correlation Coefficient (ICC, two-way random effects model, absolute agreement) for the global score reached $.92$ to $.95$, signaling high temporal measurement stability. Subscale ICCs similarly ranged between $.87$ and $.93$.
Measurement Error and Responsiveness
Psychometric evaluations have determined the Standard Error of Measurement (SEM) and the Smallest Detectable Change (SDC). The SEM for the RASQ is approximately $6.8$ to $8.2$ scale points, yielding an $SDC_{individual}$ (at the 95% confidence level) of approximately $18.8$ to $22.7$ points. Clinicians monitoring therapy-induced functional recovery can conclude that an improvement exceeding 20 points represents true clinical progress above measurement noise.
9. Factor Analysis
The structural dimensionality of the Radboud Skills Questionnaire has been scrutinized using both exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), supplemented by modern item response theory (IRT) and Rasch modeling perspectives.
Exploratory Factor Analysis (EFA)
Early principal axis factoring and principal component analyses with varimax and oblimin rotations revealed a strong general factor accounting for greater than 50% to 58% of the total variance, indicating that a unidimensional construct of “perceived upper limb functional disability” underlies the scale. However, multidimensional extraction criteria (eigenvalues > 1.0, scree plot examination) support a 3-factor hierarchical architecture accounting for roughly 66% of the cumulative variance:
- Factor 1: Household and Domestic Demands: Items measuring kitchen activities, cleaning, ironing, food preparation, and heavy lifting load heavily on this factor (factor loadings ranging from $.58$ to $.84$).
- Factor 2: Personal Care and Fine Motor Grooming: Items evaluating buttoning, zipping, washing hair, shaving, brushing teeth, and trimming nails load predominantly on this dimension (loadings from $.54$ to $.82$).
- Factor 3: Fine Manipulative, Community, and Instrumental Tasks: Items involving pen use, operating keys, turning door handles, bicycling, driving, and handwriting exhibit primary loadings between $.48$ and $.76$.
Confirmatory Factor Analysis (CFA) Fit Indices
Subsequent structural equation modeling evaluating the three-factor oblique model against a strictly unidimensional model has yielded acceptable-to-good fit indices when allowing minor error covariance between functionally twinned items (e.g., washing hands and drying hands, putting on overgarments and taking off overgarments):
- Comparative Fit Index (CFI): $.92 – .94$
- Tucker-Lewis Index (TLI): $.91 – .93$
- Root Mean Square Error of Approximation (RMSEA): $.058 – .068$ ($90% \text{ CI } [0.051, 0.075]$)
- Standardized Root Mean Square Residual (SRMR): $.048 – .056$
10. Instrument / Measurement Tool
The Radboud Skills Questionnaire is structured as an examiner-administered or self-administered patient-reported outcome inventory. Its specific operational parameters include:
- Instrument Name: Radboud Skills Questionnaire (RASQ / Radboud Skills Vragenlijst)
- Target Population: Adult individuals (≥ 18 years) presenting with unilateral or predominantly unilateral functional pathology, trauma, neurovascular impairment, or chronic pain of the upper extremity (e.g., CRPS-1, peripheral neuropathy, post-surgical status, traumatic bone/tendon injuries).
- Administration Format: Standardized paper-and-pencil or secure computerized self-report questionnaire.
- Administration Duration: Approximately 10 to 15 minutes.
- Item Inventory: 45 standardized behavioral activity items representing bimanual tasks of daily life.
- Response Format: Standardized 5-point Likert rating scale based on difficulty compared to premorbid capacity:
- 1 = Geen moeite (No difficulty)
- 2 = Weinig moeite (A little difficulty)
- 3 = Matig moeite (Moderate difficulty)
- 4 = Veel moeite (Much difficulty)
- 5 = Niet mogelijk (Impossible)
- Scoring Methodology:
- Each individual item receives an integer score from 1 to 5.
- There are no reverse-scored items; ascending scores consistently indicate greater difficulty or complete inability.
- Total Score Range: Minimum score is 45 (indicating completely unimpaired functional ability equivalent to premorbid state); maximum score is 225 (indicating total functional impairment across all 45 tasks).
- Missing Item Handling: If fewer than 10% of items (up to 4 items) are omitted, mean imputation from available completed items within the respective domain is psychometrically permissible. If more than 4 items are omitted, total aggregation is considered invalid.
11. Permissions & Fee and Test Year
The Radboud Skills Questionnaire was formally introduced to the international scientific and clinical rehabilitation community in 2000 following clinical trials conducted during the late 1990s at the Radboud University Nijmegen Medical Centre. The primary validation publication is:
Oerlemans, H. M., et al. (2000). The Radboud Skills Questionnaire: construction and psychometric properties in patients with complex regional pain syndrome-1 of one upper extremity.
Licensing and Fee Structure: The RASQ was created for open academic, non-commercial clinical, and medical research applications. It is made accessible to clinicians, physical therapists, occupational therapists, and clinical researchers without licensing royalties, provided that the original academic development is appropriately cited. Commercial health technology developers, clinical trial corporate sponsors, or digital health platforms wishing to integrate the RASQ into proprietary software systems are encouraged to contact the Department of Physical Therapy and Rehabilitation Sciences at Radboud University Medical Center to ensure adherence to intellectual property standards and certified item integrity.
12. References
- Oerlemans, H. M., Cup, E. H., De Boo, T., Goris, R. J., & Oostendorp, R. A. (2000). The Radboud Skills Questionnaire: Construction and psychometric properties in patients with reflex sympathetic dystrophy of one upper extremity. Disability and Rehabilitation, 22(5), 233–245. https://doi.org/10.1080/096382800296809
- Oerlemans, H. M., Oostendorp, R. A., de Boo, T., & Goris, R. J. (1999). Pain and reduced mobility in reflex sympathetic dystrophy: Results of a prospective, randomized controlled trial of physical therapy. Physical Therapy, 79(7), 620–635. https://doi.org/10.1093/ptj/79.7.620
- Hudak, P. L., Amadio, P. C., & Bombardier, C. (1996). Development of an upper extremity outcome measure: The DASH (disabilities of the arm, shoulder and hand). The Upper Extremity Collaborative Group (UECG). American Journal of Industrial Medicine, 29(6), 602–608. https://doi.org/10.1002/(SICI)1097-0274(199606)29:6<602::AID-AJIM4>3.0.CO;2-L
- World Health Organization. (2001). International Classification of Functioning, Disability and Health: ICF. World Health Organization. https://apps.who.int/iris/handle/10665/42407
- Birklein, F., & Schmelz, M. (2008). Neuropeptides, neurogenic inflammation, and complex regional pain syndrome (CRPS). Brain, Behavior, and Immunity, 22(1), 27–33. https://doi.org/10.1016/j.bbi.2007.03.003
- Moseley, G. L. (2004). Graded motor imagery is effective for long-standing complex regional pain syndrome: A randomised controlled trial. Pain, 108(1), 192–198. https://doi.org/10.1016/j.pain.2004.01.006