%0 Journal Article
%T The new freezing of gait questionnaire: unsuitable as an outcome in clinical trials?
%J Movement disorders clinical practice
%D 2020
%A Hulzinga, Femke
%A Nieuwboer, Alice
%A Dijkstra, Bauke W.
%A Mancini, Martina
%A Strouwen, Carolien
%A Bloem, Bastiaan R.
%A Ginis, Pieter
%V 7
%N 2
%P 199-205
%X 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.
© 2020 International Parkinson and Movement Disorder Society.
Language: en
%G en %I John Wiley and Sons %@ 2330-1619 %U http://dx.doi.org/10.1002/mdc3.12893