Researchers have identified several digital gait measures that show promise as outcome measures for clinical trials in spastic paraplegia type 7 (SPG7), one of the most common spastic ataxias. The multicenter study, involving seven centers across six countries, used wearable sensors to analyze walking patterns in SPG7 patients and healthy controls, revealing significant correlations between specific gait parameters and disease severity.
The study, published recently, addresses the need for sensitive and valid outcome measures as targeted treatment trials for spastic ataxias become a reality. The research team focused on identifying digital-motor outcomes that reflect patient-relevant health aspects, are suitable for multicenter use, and assess mobility during uninstructed walking to simulate real-life conditions.
Gait analysis was performed on 65 patients with SPG7 and 50 healthy controls. Participants underwent defined laboratory-based walking and uninstructed "supervised free walking" while wearing three wearable sensors (Opal APDM). The researchers extracted digital gait measures and assessed their ability to discriminate between patients and controls, as well as their correlation with measures of functional mobility, overall disease severity (Spastic Paraplegia Rating Scale [SPRS], including mobility subscore SPRSmobility; Scale for the Assessment and Rating of Ataxia [SARA]), and activities of daily living (Friedreich Ataxia Rating Scale [FARS-ADL]).
Among 30 hypothesis-based gait measures, 18 demonstrated at least a moderate effect size (Cliff δ > 0.5) in distinguishing patients from controls, with 17 showing similar results even in mild disease stages (SPRSmobility ≤ 9, n = 41). Spatiotemporal variability measures, such as spatial variability measure SPcmp (ρ = 0.67, p < 0.0001) and stride time CV (ρ = 0.67, p < 0.0001), exhibited the strongest correlations with functional mobility (SPRSmobility), overall disease severity (SPRS, SARA), and activities of daily living (FARS-ADL). These correlations were also confirmed in mild disease stages (e.g., SPcmp: ρ = 0.50, p < 0.0001) and during "supervised free walking" (e.g., stride time CV: ρ = -0.57, p < 0.0001).
The findings suggest that these sensor-based outcomes could be valuable in future natural history studies and treatment trials for SPG7 and other spastic ataxias. The identified digital-motor candidate outcomes have demonstrated multicenter applicability, the ability to differentiate between patients and controls, and a correlation with patient-relevant health aspects, even in the early stages of the disease. Longitudinal validation is needed to confirm their utility over time.
