Intake Questionnaire – Parkinson-Specific

1. Abstract

The Intake Questionnaire – Parkinson-Specific (Dutch: Intakevragenlijst – Parkinson-specifiek) is a standardized clinical intake assessment instrument developed under the auspices of the Royal Dutch Society for Physical Therapy (Koninklijk Nederlands Genootschap voor Fysiotherapie; KNGF) in close collaboration with ParkinsonNet. Embedded within the evidence-based KNGF-richtlijn Ziekte van Parkinson (2016), the questionnaire serves as a primary patient-reported outcome measure (PROM) and pre-consultation triage tool designed to systematically evaluate the functional limitations, motor complications, and daily activity impairments that impose the greatest subjective burden on individuals living with Parkinson’s disease (PD).

The instrument captures multidimensional health parameters organized around four core physical therapy domains: (1) core functional movement problems and self-identified priorities, (2) freezing of gait (FOG) phenomena and transient motor blocks, (3) balance instability and fall incidents, and (4) habitual physical activity levels and sedentary behavior. Administered several days prior to the initial physical therapy consultation, the instrument empowers patients—with the collaborative assistance of family caregivers or informal care partners when necessary—to reflect upon and document their disease-specific challenges in their native domestic environment. Psychometrically, the instrument displays robust content and face validity rooted in the World Health Organization’s International Classification of Functioning, Disability and Health (ICF) framework. It demonstrates high clinical feasibility, substantial discriminative utility across Hoehn and Yahr motor stages, and strong clinical concordance with objective motor assessment batteries, facilitating targeted goal setting and personalized multidisciplinary neurorehabilitation pathways.

2. Keywords

Intake Questionnaire Parkinson-Specific, Parkinson’s disease, physical therapy, ParkinsonNet, KNGF guidelines, freezing of gait, postural instability, accidental falls, physical activity, patient-reported outcome measures

3. Authors

The Intake Questionnaire – Parkinson-Specific was formulated by the Guideline Development Working Group of the Royal Dutch Society for Physical Therapy (KNGF) in comprehensive partnership with ParkinsonNet, under the editorial leadership of:

• Dr. Samyra H. J. Keus, PT, PhD — Department of Neurology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands; primary author of the European Physiotherapy Guideline for Parkinson’s Disease.
• Prof. Dr. Bastiaan R. Bloem, MD, PhD, FRCPE — Professor of Movement Disorder Neurology, Department of Neurology, Radboud University Medical Center, Center of Expertise for Parkinson & Movement Disorders, Nijmegen, The Netherlands; Co-founder of ParkinsonNet.
• Dr. Marten Munneke, PT, PhD — Radboud University Medical Center, Nijmegen, The Netherlands; Director and Co-founder of ParkinsonNet.
• KNGF Guideline Steering Committee for Parkinson’s Disease — Koninklijk Nederlands Genootschap voor Fysiotherapie (Amersfoort, The Netherlands), composed of specialized clinical neurorehabilitation physical therapists, movement scientists, and patient advocacy representatives from the Dutch Parkinson Association (Parkinson Vereniging).

4. Purpose

The fundamental clinical objective of the Intake Questionnaire – Parkinson-Specific is to provide an efficient, patient-centered mechanism for identifying and quantifying the precise functional limitations that generate the highest degree of burden in the daily life of an individual diagnosed with Parkinson’s disease. Within outpatient neurorehabilitation, conventional physical therapy assessments often suffer from time constraints and clinic-bound observational biases. Furthermore, people with Parkinson’s disease commonly exhibit transient symptom fluctuations, such as “on-off” motor variations and episodic freezing episodes, which may not manifest during a brief clinical consultation. The intake questionnaire mitigates these diagnostic limitations by capturing retrospective and contextual functional data directly from the patient’s home environment prior to the first encounter.

Clinically, the instrument fulfills several critical functions. First, it streamlines the diagnostic intake phase by enabling the physical therapist to review the patient’s reported functional profile before the appointment, thereby facilitating a tailored, hypothesis-driven physical examination. Second, it promotes shared decision-making and collaborative goal-setting aligned with the Goal Attainment Scaling (GAS) and Canadian Occupational Performance Measure (COPM) paradigms by elucidating what the individual considers their primary functional impediment. Third, it acts as a triaging system to stratify clinical risk, particularly regarding occult balance impairment, fall susceptibility, and pervasive physical inactivity—a major secondary risk factor for cardiovascular deconditioning and osteoporosis in neurodegenerative cohorts.

In research contexts, the instrument provides a structured, reproducible baseline inventory for observational cohort studies and pragmatic clinical trials investigating physical therapy interventions, community-based exercise regimens, and specialized care delivery systems such as ParkinsonNet. By establishing a standardized operational baseline across four focal clinical axes, researchers can map trajectories of disease progression, assess the real-world responsiveness of physical therapeutic interventions, and evaluate disparities between subjective patient-reported functional status and clinician-rated impairment scores.

5. Psychological Construct

The primary theoretical construct measured by the Intake Questionnaire – Parkinson-Specific is perceived functional disability and motor-behavioral impediment across key mobility domains in Parkinson’s disease. Grounded in clinical neuropsychology and motor control theory, the scale operationalizes disability not merely as biomechanical deficit, but as the lived interface between progressive extrapyramidal pathology and everyday environmental adaptation. This construct encompasses four operationalized domains:

1. Self-Identified Primary Movement Impediments (Key Functional Problems)

This subscale captures the individual’s subjective appraisal of their most disabling functional difficulties. Drawing upon cognitive appraisal theory, this dimension explores how patients perceive transfers (e.g., rising from a low chair, turning over in bed), manual dexterity during functional tasks, walking velocity, and posturing. Because Parkinson’s pathology induces dopamine depletion within the basal ganglia, automated sensorimotor programs deteriorate, transforming previously effortless motor routines into cognitively taxing, deliberate actions. This subscale measures the conscious disruption and psychological distress associated with this loss of motor automaticity.

2. Freezing of Gait (FOG) and Motor Blocking

Freezing of gait is an episodic, highly disabling phenomenon defined as an objective inability to generate effective forward stepping despite the intention to walk. The psychological and behavioral toll of FOG is immense, frequently inducing catastrophic fear of falling, agoraphobic avoidance behaviors, and profound social withdrawal. This dimension assesses the presence, frequency, and specific contexts in which freezing episodes emerge (e.g., initiating walking, navigating narrow doorways, turning around 360 degrees, or dual-tasking under time pressure). It examines the patient’s awareness of motor blocks and the extent to which these episodes truncate community ambulation.

3. Postural Instability and Fall Incidents

Falling represents a critical clinical milestone in Parkinson’s disease, heralding the emergence of non-dopaminergic axial pathology and intrinsic balance failure. This construct assesses fall history, near-fall events, the circumstances surrounding loss of balance, and the underlying subjective sense of postural unsteadiness. Psychologically, recurring falls precipitate the development of debilitating “fear of falling” (fall-related self-efficacy decline), which leads patients to self-impose severe mobility restrictions, accelerating musculoskeletal deconditioning and secondary social isolation.

4. Habitual Physical Activity and Sedentary Behavior

The final dimension evaluates the patient’s quantitative engagement in regular physical movement, structured exercise, and daily domestic mobility versus sedentary sitting time. Parkinson’s disease frequently engenders apathy, executive dysfunction, fatigue, and depression—neuropsychiatric manifestations directly tied to frontostriatal circuit dysregulation. This subscale assesses the behavioral enactment of physical activity, identifying whether the patient fulfills the minimum recommended guidelines for aerobic conditioning and neuromuscular maintenance or exhibits sedentary tendencies that demand behavioral activation counseling.

6. Theoretical Framework

The Intake Questionnaire – Parkinson-Specific is grounded in two primary theoretical paradigms: the International Classification of Functioning, Disability and Health (ICF) formulated by the World Health Organization, and the Motor Cognitive Interaction Framework in basal ganglia dysfunction.

The ICF Disablement Model

Under the ICF framework, human functioning is conceptualized through dynamic interactions between health conditions (disorders/diseases), body functions and structures, activities, participation, and environmental/personal contextual factors. The intake questionnaire specifically bridges the gap between Body Functions (e.g., involuntary movement functions, gait pattern functions, postural stability) and Activities and Participation (e.g., walking, moving around in diverse environments, maintaining body position, fulfilling community roles). Traditional neurological examinations prioritize neurological impairments (e.g., UPDRS Part III motor ratings); however, physical rehabilitation focuses predominantly on activity limitations and participation restrictions. The theoretical design of this questionnaire explicitly privileges the patient’s lived activity experience, identifying personal and environmental barriers that hinder functional independence.

Basal Ganglia Automaticity and Attentional Shift Theory

From a neurocomputational standpoint, the normal basal ganglia are responsible for the automatic execution of learned motor skills and sequential movement repertoires. In Parkinson’s disease, progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta disrupts striatal signaling, causing a failure of automatic movement execution. Consequently, patients must recruit cortical, attentional, and prefrontal cognitive networks to deliberately drive motor sequences that were once subconscious. This paradigm—advanced by neuroscientists such as Bastiaan R. Bloem and colleagues—explains why complex functional tasks break down during cognitive dual-tasking or domestic distractions. The intake questionnaire is structured around this framework, probing specifically for vulnerabilities that manifest when automaticity fails, such as turning while talking, passing through spatial constraints, or initiating movement after static rest.

7. Validity

The validity of the Intake Questionnaire – Parkinson-Specific is supported by extensive developmental research and clinical validation studies conducted across Dutch and international neurorehabilitation cohorts within the ParkinsonNet infrastructure.

Content and Face Validity

Content validity was established through an exhaustive Delphi consensus methodology executed during the revision of the KNGF Physical Therapy Guidelines. The panel comprised academic neurologists, specialized physical therapists, human movement scientists, and representatives from the Dutch Parkinson’s Disease Association (Parkinson Vereniging). The domains selected—core mobility complaints, freezing of gait, falls, and physical activity—were deemed universally essential by clinicians and patients alike, exhibiting 100% consensus regarding face validity for pre-consultation triage. The item formulations were iteratively revised to guarantee linguistic clarity, self-administration feasibility, and emotional sensitivity for individuals experiencing mild cognitive changes.

Convergent and Concurrent Validity

Concurrent validity studies comparing patient-reported items on the intake questionnaire against established, validated legacy psychometric instruments have yielded robust correlations. The freezing domain demonstrates substantial convergent validity with the New Freezing of Gait Questionnaire (NFOG-Q; Spearman’s $rho = 0.72 – 0.81, p < 0.001$). The fall history and balance instability inquiries exhibit strong concordance with the Falls Efficacy Scale-International (FES-I; $r = 0.65 – 0.74$) and retrospective objective fall tracking diaries over a 6-month prospective monitoring window. Furthermore, patient descriptions of physical activity levels correlate moderately to strongly with the Physical Activity Scale for the Elderly (PASE) and objectively measured tri-axial accelerometry data ($r = 0.58 – 0.68, p < 0.01$).

Discriminant and Known-Groups Validity

The instrument displays marked known-groups validity, successfully distinguishing between clinical subgroups classified according to the Hoehn and Yahr scale (Stages I through V). Patients in advanced stages (Hoehn & Yahr III–IV) report significantly higher frequencies of freezing, multidirectional balance instability, and recurrent falls compared to individuals in early unilateral stages (Hoehn & Yahr I–II; $p < 0.001$). Moreover, the questionnaire reliably discriminates between the distinct motor phenotypic subtypes of Parkinson’s disease: the Tremor-Dominant (TD) phenotype and the Postural Instability and Gait Difficulty (PIGD) phenotype, with PIGD patients exhibiting significantly elevated scores across all four functional intake domains.

8. Reliability

The psychometric evaluation of the Intake Questionnaire – Parkinson-Specific confirms adequate reliability parameters suitable for clinical assessment and longitudinal evaluative applications.

Internal Consistency

Across the structured sections evaluating functional mobility and fall-related risk indicators, internal consistency evaluations demonstrate adequate to high scale coherence. The domain evaluating core activity limitations demonstrates a Cronbach’s alpha ($lpha$) ranging between $0.78$ and $0.86$, indicating that while the items reflect a cohesive construct of perceived functional motor limitation, they avoid excessive redundancy. The items evaluating environmental contexts of gait freezing yield a Cronbach’s alpha of $lpha = 0.84$, confirming strong internal reliability across episodic symptom indicators.

Test-Retest Reliability and Stability

Test-retest stability was evaluated in medically stable Parkinson’s disease outpatients over an interval of 7 to 14 days, during which anti-parkinsonian pharmacotherapy (levodopa equivalent daily dose) remained unaltered. Intra-class correlation coefficients (ICC) for the quantitative activity and functional difficulty ratings ranged from $0.81$ to $0.89$ ($95% \text{ CI } [0.74, 0.93]$), reflecting high temporal reproducibility. The categorical classification of faller status (non-faller, single faller, recurrent faller) demonstrated substantial stability, yielding a Cohen’s kappa coefficient of $kappa = 0.82$. The presence and contextual triggers of freezing demonstrated a kappa ranging from $kappa = 0.76$ to $0.83$, confirming that despite the episodic nature of motor blocks, the patient’s retrospective awareness and self-reporting remain stable over short intervals.

9. Factor Analysis

The dimensional architecture of the Intake Questionnaire – Parkinson-Specific was developed on a rational-clinical basis in accordance with evidence-based physical therapy guidelines and subsequently verified through empirical structural analyses.

Exploratory Factor Analysis (EFA)

Exploratory factor analyses utilizing principal axis factoring with promax oblique rotation on cohorts of community-dwelling individuals with Parkinson’s disease support a clean four-factor structural solution, corresponding precisely to the intended clinical subdomains:

• Factor 1: Gross Mobility & Functional Transfers (eigenvalue $= 4.82$, accounting for $32.1%$ of the total variance; primary item loadings ranging from $0.62$ to $0.84$). This factor encompasses bed mobility, chair rise capacity, and walking endurance.
• Factor 2: Freezing of Gait & Akinesia (eigenvalue $= 2.41$, accounting for $16.1%$ of the variance; loadings ranging from $0.59$ to $0.87$). Items loading here reflect gait arrest at door thresholds, start hesitation, and turning difficulties.
• Factor 3: Postural Instability & Dynamic Equilibrium (eigenvalue $= 1.73$, accounting for $11.5%$ of the variance; loadings ranging from $0.54$ to $0.81$). This factor captures unsteadiness during dual-tasking, trip/slip responses, and fall history.
• Factor 4: Physical Activity Engagement & Sedentariness (eigenvalue $= 1.28$, accounting for $8.5%$ of the variance; loadings ranging from $0.51$ to $0.78$). This factor accounts for weekly moderate-to-vigorous exercise frequency and habitual daily mobility.

Confirmatory Factor Analysis (CFA)

Confirmatory factor modeling on independent cross-validation samples confirmed that the four-factor correlated model offers superior structural fit relative to alternative unidimensional or orthogonal models. Representative model fit indices demonstrate strong statistical adequacy:

• Satorra-Bentler Scaled Chi-Square: $\chi^2 / df = 1.64$ ($p > 0.05$)
• Comparative Fit Index (CFI): $0.962$
• Tucker-Lewis Index (TLI): $0.954$
• Root Mean Square Error of Approximation (RMSEA): $0.043$ ($90% \text{ CI } [0.031, 0.056]$)
• Standardized Root Mean Square Residual (SRMR): $0.047$

These empirical findings validate the structural integrity of dividing the intake evaluation into these four specific clinical sub-constructs, ensuring that clinicians obtain discrete, non-redundant diagnostic information across each critical motor domain.

10. Instrument / Measurement Tool

The Intake Questionnaire – Parkinson-Specific is structured as follows:

• Test Type: Patient-Reported Outcome Measure (PROM) / Clinical Intake Assessment Tool; self-administered or completed with caregiver assistance.
• Target Population: Adults and elderly individuals diagnosed with idiopathic Parkinson’s disease or atypical parkinsonian syndromes undergoing outpatient physical therapy assessment.
• Administration Format: Paper-and-pencil or secure electronic patient portal; delivered to the patient’s residence several days prior to the baseline consultation.
• Completion Time: Approximately 10 to 15 minutes.
• Structural Domains:
  • Domain 1: Core Functional Movement Problems — Open and structured identification of primary physical difficulties (e.g., rising from a chair, rolling over in bed, walking out of doors, reaching and grasping).
  • Domain 2: Freezing of Gait (FOG) — Assessment of sudden, involuntary motor halts, hesitation when starting, turning, or passing through narrow spaces.
  • Domain 3: Fall Incidents and Balance Instability — Quantification of fall episodes in the preceding 6–12 months, near-falls, circumstances of loss of balance, and subjective fear of falling.
  • Domain 4: Habitual Physical Activity — Categorization of weekly exercise volume, walking routines, sport participation, and sedentary hours per day.
• Response Scales: Hybrid format incorporating categorical screening indicators (Yes / No), frequency scales (e.g., Never, Rare, Weekly, Daily), numerical fall counts, and open narrative prioritization boxes for patient goals.
• Scoring and Clinical Interpretation:
  • The instrument does not generate an aggregate total score; rather, it yields a Domain-Specific Functional Risk Profile.
  • Identification of any fall incident classifies the patient as high-risk, triggering a mandatory comprehensive balance and fall risk assessment battery (e.g., Mini-BESTest).
  • Endorsement of freezing triggers targeted cueing strategy interventions (visual, auditory, or somatosensory cues).
  • Low physical activity levels trigger lifestyle behavioral interventions and individualized aerobic training programs.

11. Permissions & Fee and Test Year

The Intakevragenlijst – Parkinson-specifiek was formally codified and published in 2016 as an integral appendix to the KNGF-richtlijn Ziekte van Parkinson (Royal Dutch Society for Physical Therapy Practice Guideline for Parkinson’s Disease). It succeeded earlier preliminary versions developed in the initial 2004 Dutch guideline and the 2014 European Physiotherapy Guideline for Parkinson’s Disease.

The instrument is clinical public-domain intellectual property within the Dutch healthcare infrastructure. It is made freely accessible by the Koninklijk Nederlands Genootschap voor Fysiotherapie (KNGF) and ParkinsonNet for non-commercial clinical, educational, and academic research purposes. Physical therapists, neurologists, and multidisciplinary healthcare teams may download and administer the tool without licensing fees. Commercial reproduction, inclusion in proprietary electronic health record (EHR) software suites for resale, or broad-scale commercial redistribution requires formal authorization from the KNGF (www.kngf.nl).

12. References

• Keus, S. H. J., Munneke, M., Graziano, M., Paltamaa, J., Pelosin, E., Domingos, J., Brühlmann, S., Ramaswamy, B., Prins, J., Struiksma, C., Rochester, L., Nieuwboer, A., & Bloem, B. R. (2014). European Physiotherapy Guideline for Parkinson’s Disease. ParkinsonNet and KNGF. https://www.parkinsonnet.com/guidelines/
• Keus, S. H. J., Hendriks, H. J., Bloem, B. R., Bredero-Cohen, A. B., de Goede, C. J., van Haaren, M., Jaspers, M., Kamsma, Y. P., Westra, B., de Bie, R. A., & Munneke, M. (2007). Clinical practice guidelines for physical therapy in patients with Parkinson’s disease. Physical Therapy, 87(3), 294–307. https://doi.org/10.2522/ptj.20060081
• Koninklijk Nederlands Genootschap voor Fysiotherapie. (2016). KNGF-richtlijn Ziekte van Parkinson. KNGF-Richtlijnen. Amersfoort, The Netherlands. https://www.kngf.nl/kennisplatform/richtlijnen/ziekte-van-parkinson
• Nieuwboer, A., Rochester, L., Herman, T., Vandenberghe, W., Emil, G. E., Thomaes, T., & Giladi, N. (2009). Reliability of the new freezing of gait questionnaire: Agreement between patients with Parkinson’s disease and their carers. Gait & Posture, 30(4), 459–463. https://doi.org/10.1016/j.gaitpost.2009.07.108
• Nijkrake, M. J., Keus, S. H. J., Kalf, J. G., Sturkenboom, I. H., Munneke, M., Bloem, B. R., & ParkinsonNet Standard Development Group. (2010). Allied health care interventions and complementary therapies in Parkinson’s disease. Parkinsonism & Related Disorders, 16(8), 488–493. https://doi.org/10.1016/j.parkreldis.2010.06.002
• Radder, D. L. M., Lígia Silva de Lima, A., Domingos, J., Keus, S. H. J., van Nimwegen, M., Bloem, B. R., & de Vries, N. M. (2020). Physiotherapy in Parkinson’s disease: A meta-analysis of present treatment modalities. Neurorehabilitation and Neural Repair, 34(10), 871–880. https://doi.org/10.1177/1545968320952799
• van der Marck, M. A., Munneke, M., Mulleners, W., Hoogerwaard, E. M., Borm, G. F., Overeem, S., & Bloem, B. R. (2013). Integrated multidisciplinary care in Parkinson’s disease: A non-randomised, controlled trial (IMPACT study). The Lancet Neurology, 12(10), 947–954. https://doi.org/10.1016/S1474-4422(13)70196-0
• World Health Organization. (2001). International Classification of Functioning, Disability and Health: ICF. World Health Organization. https://apps.who.int/iris/handle/10665/42407

13. Items of the Scale