Construction of freezing of gait questionnaire for patients with Parkinsonism

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. (C) 2000 Elsevier Science Ltd. All rights reserved.