Abstract
Background: Freezing of gait (FOG) is a common gait deficit in Parkinson's disease. The New Freezing of Gait Questionnaire (NFOG-Q) is a widely used and valid tool to quantify freezing of gait severity. However, its test-retest reliability and minimal detectable change remain unknown. Objective: To determine the test-retest reliability and responsiveness of the NFOG-Q. Methods: Two groups of freezers, involved in 2 previous rehabilitation trials, completed the NFOG-Q at 2 time points (T1 and T2), separated by a 6-week control period without active intervention. Sample 1 (N = 57) was measured in ON and sample 2 (N = 14) in OFF. We calculated various reliability statistics for the NFOG-Q scores between T1 and T2 as well as correlation coefficients with clinical descriptors to explain the variability between time points. Results: In sample 1 the NFOG-Q showed modest reliability (intraclass correlation coefficient = 0.68 [0.52–0.80]) without differences between T1 and T2. However, a minimal detectable change of 9.95 (7.90–12.27) points emerged for the total score (range 28 points, relative minimal detectable change of 35.5%). Sample 2 showed largely similar results. We found no associations between cognitive-related or disease severity–related outcomes and variability in NFOG-Q scores. Conclusions: We conclude that the NFOG-Q is insufficiently reliable or responsive to detect small effect sizes, as changes need to go beyond 35% to surpass measurement error. Therefore, we warrant caution in using the NFOG-Q as a primary outcome in clinical trials. These results emphasize the need for robust and objective freezing of gait outcome measures.
Original language | English (US) |
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Pages (from-to) | 199-205 |
Number of pages | 7 |
Journal | Movement Disorders Clinical Practice |
Volume | 7 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1 2020 |
Keywords
- freezing of gait
- minimal detectable change
- new freezing of gait questionnaire
- reliability
ASJC Scopus subject areas
- Neurology
- Clinical Neurology