Hulzinga Femke, Nieuwboer Alice, Dijkstra Bauke W, Mancini Martina, Strouwen Carolien, Bloem Bastiaan R, Ginis Pieter
KU Leuven, Department of Rehabilitation Sciences, Neurorehabilitation Research Group Leuven Belgium.
Department of Neurology Oregon Health & Science University Portland Oregon USA.
Mov Disord Clin Pract. 2020 Jan 14;7(2):199-205. doi: 10.1002/mdc3.12893. eCollection 2020 Feb.
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.
To determine the test-retest reliability and responsiveness of the NFOG-Q.
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.
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.
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.
冻结步态（FOG）是帕金森病常见的步态缺陷。新型冻结步态问卷（NFOG-Q）是一种广泛使用且有效的工具，用于量化冻结步态的严重程度。然而，其重测信度和最小可检测变化尚不清楚。
确定NFOG-Q的重测信度和反应性。
两组曾参与过两次康复试验的冻结步态患者，在两个时间点（T1和T2）完成NFOG-Q测试，中间间隔6周的无积极干预的对照期。样本1（N = 57）在“开”期测量，样本2（N = 14）在“关”期测量。我们计算了T1和T2之间NFOG-Q分数的各种信度统计数据，以及与临床描述指标的相关系数，以解释时间点之间的变异性。
在样本1中，NFOG-Q显示出中等信度（组内相关系数 = 0.68 [0.52 - 0.80]），T1和T2之间无差异。然而，总分的最小可检测变化为9.95（7.90 - 12.27）分（范围28分，相对最小可检测变化为35.5%）。样本2显示出大致相似的结果。我们发现认知相关或疾病严重程度相关结果与NFOG-Q分数变异性之间无关联。
我们得出结论，NFOG-Q在检测小效应量方面的可靠性或反应性不足，因为变化需要超过35%才能超过测量误差。因此，我们在将NFOG-Q用作临床试验的主要结局时需谨慎。这些结果强调了对稳健且客观的冻结步态结局测量指标的需求。
