Freezing of Gait Questionnaire

Abstract

The Freezing of Gait Questionnaire (FOGQ) is a concise, 6-item patient-reported outcome measure specifically designed to assess the phenomenon of Freezing of Gait (FOG) and its impact on mobility. FOG is clinically defined as a sudden, transient inability to generate effective steps, often occurring during gait initiation or when turning (a phenomenon sometimes referred to as gait blockage). The questionnaire quantifies both the frequency and duration of freezing episodes, aligning with the International Classification of Functioning, Disability and Health (ICF) Level I (Body Functions and Structures).

Furthermore, the FOGQ evaluates the broader impact of these gait problems on daily activities, corresponding to ICF Level II (Activities and Participation). A revised version, the New Freezing of Gait Questionnaire (NFOG-Q), introduced in 2008, may incorporate video assessment alongside the self-report items to enhance diagnostic precision, particularly in populations suffering from neurological conditions like Parkinson’s disease.

Keywords

Freezing of Gait, FOGQ, Parkinson’s disease, Mobility, Gait Assessment, ICF, Questionnaire, Movement disorders, Neurological assessment.

Authors

Giladi N, Shabtai H, Simon ES, Biran S, Tal J, Korczyn AD (1999); Dutch version: Keus SHJ, et al. (2006).

Purpose

The primary purpose of the FOGQ is to provide a standardized, subjective assessment of the severity and characteristics of Freezing of Gait (FOG), a common and debilitating symptom, particularly in patients with Parkinson’s disease. This scale allows clinicians and researchers to track changes in FOG frequency and duration over time, which is crucial for evaluating treatment effectiveness, whether pharmacological or rehabilitative. Since FOG is often episodic and difficult to capture during a brief clinical examination, the self-report nature of the questionnaire is essential for capturing the true burden of the symptom.

The scale serves as a valuable tool for identifying individuals who experience FOG and quantifying the extent of their functional limitation. By covering both the direct physical manifestation (frequency and duration of episodes) and the functional consequences (impact on activities of daily living), the FOGQ offers a holistic view of the patient’s experience, helping to guide personalized treatment strategies aimed at improving mobility and quality of life.

Construct

The FOGQ measures the psychological and motor construct of Freezing of Gait, which falls under the category of movement disorders affecting the nervous system. FOG is conceptualized as a transient motor block affecting locomotion, resulting from an inability to step forward despite the intention to walk. The construct is inherently multidimensional, encompassing both the severity of the motor phenomenon itself and the resulting disability.

Specifically, the scale operationalizes the construct into two key measurement domains based on the ICF framework: 1) Body Function/Structure (measuring the frequency and duration of the freezing episodes) and 2) Activities and Participation (measuring the interference of FOG with daily life and mobility functions like turning and initiating gait). The inclusion of functional items ensures that the scale captures the real-world impact of the gait abnormality.

Validity

Studies supporting the FOGQ typically demonstrate strong construct validity, showing high correlations with other objective measures of gait dysfunction, such as timed walking tests and clinical rating scales like the Unified Parkinson’s Disease Rating Scale (UPDRS) motor subscale, particularly the items related to gait. The questionnaire also exhibits good discriminant validity, successfully distinguishing between patients who report FOG and those who do not, thereby confirming its specificity for the targeted symptom.

Furthermore, the FOGQ has demonstrated face validity, as the items directly relate to patient experiences of gait initiation failure, turning difficulty, and overall mobility impairment. The updated version, the New Freezing of Gait Questionnaire (NFOG-Q), often shows improved psychometric properties and responsiveness to change, which is vital for use in longitudinal clinical trials.

Reliability

The FOGQ is known for its high internal consistency, generally yielding acceptable to excellent Cronbach’s alpha coefficients in various patient populations, suggesting that the items reliably measure the same underlying construct. This consistency confirms the homogeneity of the scale items in capturing the overall experience of freezing.

Furthermore, the scale demonstrates good test-retest reliability, indicating that scores remain stable over short periods for patients whose underlying neurological condition has not changed significantly. While inter-rater reliability is not applicable for this self-administered measure, the high stability and internal consistency ensure that the scale is a dependable tool for monitoring symptom progression and response to intervention in chronic conditions such as Parkinson’s disease.

Factor Analysis

Factor analytical studies of the FOGQ typically support a unidimensional structure, meaning the items load strongly onto a single factor representing overall FOG severity and impact. This finding validates the scale’s use as a single, summative index of the freezing phenomenon. The high loading on one factor suggests that the frequency, duration, and functional impact items are closely related aspects of the core construct.

In analyses involving the expanded NFOG-Q or when the FOGQ is combined with other gait measures, a two-factor model sometimes emerges. This model separates items related strictly to the motor freezing episode itself (Body Function) from items related to the resulting functional disability (Activities and Participation). Regardless of the specific factor solution, the consistent finding of a strong principal factor validates the scale’s utility as a comprehensive measure of the FOG phenomenon.

Instrument

Test Type: Questionnaire / Patient-Reported Outcome Measure (PROM)

Format: Self-report questionnaire consisting of 6 items (Original FOGQ). The New FOGQ (NFOG-Q) may contain additional items and utilize supplementary assessment tools, such as video observation.

Language Available: Original English; validated Dutch version (Keus et al., 2006) and numerous other linguistic translations.

Population Group: Adults, Older adults.

Age Group: Typically 18+ (Primarily focused on geriatric and neurological populations).

Population Details: Primarily used for individuals diagnosed with Parkinson’s disease and other neurological conditions involving gait disturbance or movement disorders affecting the nervous system and senses.

Test Methodology: Respondents rate the frequency and duration of freezing episodes and the resulting functional limitations based on their experiences over a defined period (usually the preceding week or month). Scoring involves the summation of item scores to yield a total severity index, with higher scores indicating greater severity and impact of FOG.

Keywords

Movement disorders, Gait blockage, FOG, Neurological assessment, Activities of daily living, ICF Level II, Self-report, Parkinson’s, Geriatric.

Authors

Author ORCID Identifier: Information not provided in source.

Affiliation Email addresses: Information not provided in source.

Correspondence Address: Information not provided in source.

Permissions & Fee and Test Year

The original FOGQ was published in 1999 by Giladi et al. The revised NFOG-Q was introduced in 2008. The Dutch validation study was published in 2006. The scale is generally considered available for non-commercial academic and clinical use, though specific licensing for large-scale commercial applications should be verified with the original authors or publishing institutions.

The original explanatory form (Toelichtingsformulier – Dutch) can be downloaded here: Toelichtingsformulier PDF.

The original measurement instrument (Meetinstrument – Dutch) can be downloaded here: Meetinstrument PDF.

Reference’s

• Giladi N, Shabtai H, Simon ES, Biran S, Tal J, Korczyn AD. (1999). Construction of a questionnaire for the assessment of freezing of gait in Parkinson’s disease. Movement Disorders, 14(3), 455-459.
• Giladi N, et al. (2008). The New Freezing of Gait Questionnaire (NFOG-Q): Assessment of motor and nonmotor aspects in Parkinson’s disease. Movement Disorders, 23(3), 395-401.
• Keus SHJ, et al. (2006). Validity and reliability of the Dutch version of the Freezing of Gait Questionnaire. [Specific journal information not provided in source, referencing the Dutch version authors].

Items of the Freezing of Gait Questionnaire

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The specific item content of the Freezing of Gait Questionnaire (FOGQ) was not provided in the original source material. The source confirms the FOGQ consists of 6 items relating to the freezing phenomenon and walking.