Objective: To evaluate the sensitivity, consistency and test-retest reliability of several freezing of gait (FOG)-provoking tests in the homes of people with Parkinson’s disease (PD) before and after dopaminergic medication intake (OFF and ON).

Background: The paroxysmal and heterogeneous nature of FOG induces challenges to the objective assessment of the presence of FOG and its severity. Besides standardized ratings, a sensitive, consistent and reliable FOG-provoking protocol is needed to obtain robust outcomes. So far, a comprehensive evaluation of various tasks in freezers, OFF and ON medication, is lacking.

Method: A FOG-provoking protocol was performed by 63 daily freezers at 2 time points (T1 and T2, ~5 weeks later) in OFF and ON, within a clinical trial. It consisted of: four meter walk (4MW); Timed-Up and Go (TUG) single- and dual-task (ST and DT; serial-3 subtraction); 360° turns in place (ST and DT); navigating a doorway with turn (hotspot door); and a personalized “hotspot” task. Using standardized criteria, video annotation was performed to determine the presence of FOG or festination (FOG+) and its severity (percentage time frozen: %TF) per task. Sensitivity to elicit FOG (%FOG+) was tested for the full cohort at T1. Consistency (classification agreement for T1 and T2) and test-retest reliability (intra-class correlation (ICC) for %TF) were assessed in the sham intervention group (N=26).

Results: The median duration to perform the protocol was 8.86 (IQR: 4.97) minutes. Sensitivity, consistency and test-retest reliability were higher in OFF than in ON, and higher for 360° turns compared to other tasks. For the TUG and 360° turns, DT improved metrics compared to ST. The hotspot door performed better overall than the TUG (ST), achieving high reliability in ON, while the 4MW performed poorly. Although the personalized hotspot was sensitive at T1, its test-retest reliability was lower.

Conclusion: Sensitivity, consistency, and test-retest reliability varied from poor to excellent depending on the condition. Testing after overnight withdrawal of PD medication and with DT gave the best results. In agreement with previous work, the 360° turns were highly sensitive, consistent, and reliable even in ON. Based on this, we propose including the TUG (DT), 360° turns (ST and DT) and hotspot door (DT) in the OFF state as the optimal FOG-provoking protocol.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sensitivity-consistency-and-test-retest-reliability-of-home-based-freezing-of-gait-provoking-tests-in-people-with-parkinsons-disease/