Towards patient-relevant, trial-ready digital motor outcomes for SPG7: a cross-sectional prospective multi-center study (PROSPAX)
Bibliographic record
Abstract
Abstract Background and Objectives With targeted treatment trials on the horizon, identification of sensitive and valid outcome measures becomes a priority for the >100 spastic ataxias. Digital-motor measures, assessed by wearable sensors, are prime outcome candidates for SPG7 and other spastic ataxias. We here aimed to identify candidate digital-motor outcomes for SPG7 – as one of the most common spastic ataxias – that: (i) reflect patient-relevant health aspects, even in mild, trial-relevant disease stages; (ii) are suitable for a multi-center setting; and (iii) assess mobility also during uninstructed walking simulating real-life. Methods Cross-sectional multi-center study (7 centers, 6 countries). Unaided walking was assessed in 65 patients with SPG7 and 50 unrelated healthy controls using 3 wearable sensors (Opal APDM). Digital gait measures were correlated to measures of disease severity (SARA, SPRS; including mobility-relevant subscores SPRS 1315291292025 , SARA PG ) and activities of daily living (FARS-ADL). The task set included lab-based defined gait tasks, complemented by uninstructed ‘supervised free walking’. Results Among 30 hypothesis-based gait measures, 18 demonstrated at least moderate effect size (Cliff’s δ>0.5) in discriminating SPG7 patients from controls, and 17 even in mild disease stages (SPRS mobility ≤9). Spatiotemporal variability measures such as the spatial variability composite measure SPcmp (ρ=0.67, p=<0.0001), Stride Time CV (ρ=0.67, p=<0.0001) and Swing CV (ρ=0.64, p=<0.0001) showed the highest correlations with clinician-reported mobility scores (SPRS mobility ), and overall disease severity (SPRS, SARA). Overall, top-ranked measures also correlated with patient-relevant functional deficits in everyday life activities (FARS-ADL). In mild disease stages (SPRS mobility ≤9, n=41), Swing CV (ρ=0.53, p=<0.0001) and SPcmp (ρ=0.50, p=<0.0001) correlated with SPRS mobility . In the uninstructed ‘supervised free walking’ task, the correlations between spatiotemporal variability measures (Stride Time CV, Stride Length CV, Swing CV) and SPRS mobility could be confirmed; additionally, Gait Speed (ρ=-0.59, p=<0.0001) was highly correlated with SPRS mobility . Discussion We here identified trial-ready digital-motor candidate outcomes for the spastic ataxia SPG7, all characterized by proven multi-center applicability, ability to discriminate patients from controls, and correlation with measures of disease severity – even in mild disease stages –, and patient-relevant everyday function. If validated longitudinally, these sensor outcomes might inform future natural history and treatment trials in SPG7 and other spastic ataxias.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".