Construction of freezing of gait questionnaire for patients with Parkinsonism

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Abstract

Background: Freezing of gait (FOG) is a common, poorly understood, parkinsonian symptom interfering with daily functioning and quality of life. Assessment of FOG is complex because of the episodic nature of this symptom, and the influence of mental and environmental factors on it.

Objective: To design a self-reportable reliable questionnaire for FOG.

Method: A questionnaire consisting of 16 items regarding gait and falls was administered together with the Unified Parkinson's Disease Rating Scale (UPDRS) to 40 Parkinson's disease (PD) patients (26 males) with a mean age of 72.3±9.3 years and mean Hoehn and Yahr (H&Y) stage at “Off” of 2.85±0.84. A principal component analysis with Varimax rotation was conducted on the results. Item analyses were performed and reliability computed for an abbreviated FOG questionnaire.

Results: Based on these analyses, a short (six item) FOG questionnaire was constructed, which was found to be highly reliable (Cronbach alpha=0.94) for assessment of FOG and with moderate correlation with the activity of daily living (ADL) and motor parts of the UPDRS (0.43 and 0.40, respectively). Moderate correlation was also found with the FOG item at the ADL part of the UPDRS (alpha=0.66 for the “Off” and 0.77 for the “On” state).

Conclusion: The FOG questionnaire that was constructed is highly reliable in assessing freezing of gait, unrelated to falls, in patients with PD.

Introduction

Freezing of gait (FOG) is a prevalent and disabling symptom in Parkinson's disease (PD) [1] and may be even more common in other parkinsonian syndromes [2]. Assessing FOG is difficult due to the great variability of its manifestations within each patient. This variability is the result of FOG being affected by numerous parameters including: severity of the disease and the motor state (“On”/“Off”), visual input, tight alleys, response to variable tricks, and relation to specific gait patterns such as gait initiation or turns, cognitive factors such as attention, anxiety and stress [3]. Seventy five percent of PD patients suffering from FOG reported that this problem is most disturbing at home or out of the neurologist's office [4]. The poor correlation of reported FOG with observed FOG during the exam conducted in the office makes it impractical to assess this symptom observationally. Only extended periods of observation, in a variety of daily activities, can provide a reliable assessment of FOG. Consequently, researchers have little choice but to rely on patients' self-reports for quantification of FOG.

To date, a number of different scales have been developed to assess FOG [5], [6]. However, the adequacy of these scales in terms of reliability and validity has never been demonstrated. The Unified Parkinson's Disease Rating Scale (UPDRS), which is the most commonly used scale for assessing parkinsonian severity [7], contains only two items relating to FOG. One of these, appearing in the ADL section of the scale, evaluates FOG by asking the patient, relating FOG severity to the appearance of falls. The other item assesses gait objectively on exam.

Because of the repercussions of FOG on patients' function and quality of life it is important to assess this symptom more comprehensively. Therefore, we set out to construct Gait and Falls Questionnaire that will be both reliable and comprehensive to assess gait symptoms and falls.

Section snippets

Subjects and method

We constructed a questionnaire containing 16 questions about gait and falls. This questionnaire was administered to 40 patients (26 males) with PD diagnosed according to the United Kingdom Brain Bank clinical criteria [8], being treated at the Movement Disorders Unit of the Tel Aviv Sourasky Medical Center in Israel. Patients with dementia according to DSM IV criteria were excluded. The mean age was 72.3±9.3 years (mean ±SD; range: 44–87). Mean disease duration was 7.6±6.3 years (range: 1–24)

Scale construction

A PCA of the 16 interval level items from the extended gait and falls questionnaire (Appendix A) revealed one large component consisting of 10 items (Appendix A—marked with asterisk) accounting for 58.6% of the variance. The remaining two components with eigenvalues over 1.0 accounted for very little variance relative to the first component (11.3 and 7.1%, respectively). In addition, the scales suggested by these two components correlated highly with that suggested by the first principal

Discussion

FOG is a very disturbing and common symptom in parkinsonism with variable presentations [1], [2]. The common observation that in most patients FOG is most severe out of the doctor's office or the gait lab makes it a difficult symptom to evaluate objectively [4], [5], [6], [7], [8], [9]. FOG evaluation is complicated further by its episodic nature and the strong effect of behavioral factors as well as its response to “motor tricks” [10], [11].

In the present study we have constructed and

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