F039 Q-Motor measures show strong and consistent cross sectional correlations with core HD clinical endpoints across PROOF-HD, PRIDE-HD, LEGATO-HD and TRACK-HD

<h3>Background</h3> Q-Motor measures have been employed in multiple clinical trials in HD and beyond. They lack subjective errors, rater bias and placebo responses and reveal more sensitivity to detect treatment effects and disease progression in manifest and premanifest HD than clinical scales. <h3>Objective</h3> To explore correlations and reproducibility between Q-Motor measures and clinical measures of global disability (cUHDRS), global function (TFC) and motor dysfunction (UHDRS-TMS) across different studies in HD. <h3>Methods</h3> The core Q-Motor tests ‘finger tapping’ (digitomotography) and ‘pronate/supinate hand tapping’ (dysdiadochomotography) were collected and analyzed at the baseline visits of the studies PRIDE-HD, LEGATO-HD, TRACK-HD and PROOF-HD across treatment groups. The primary Q-Motor tapping endpoint ‘Inter-Onset-Interval’ (IOI) was extracted and correlated to the cUHDRS [PROOF-HD/TRACK-HD], TFC and UHDRS-TMS and regressions were compared across studies. <h3>Results</h3> The analyses revealed robust correlations at baseline between the finger tapping IOI mean times and the cUHDRS [r=-0.534 to -0.715], TFC [r=-0.347 to -0.507] and UHDRS-TMS [r=-0.383 to 0.747] (p &lt;0.00001 for all) - see figure 1–3. Similar results were observed for the pronate/supinate hand tapping task and with IOI-SD (a measure of variability) and other tapping measures across tasks - see figure 4. Regression lines revealed similar and consistent slopes across the studies for all measures assessed. <h3>Conclusion</h3> Q-Motor assessments are highly correlated to disease stage, severity and clinical disability in HD as assessed by the cUHDRS, TFC and UHDRS-TMS. This was observed across all Q-Motor measures assessed. The slopes of the regression lines were virtually identical across the four independent studies suggesting a high reproducibility of the link between Q-Motor measures and disease severity and progression.