G.O.16: Reliability and validity of the ACTIVE-mini (Ability Captured Through Interactive Video Evaluation-mini) to quantify infant movement

Abstract

The success of clinical trials in infants with spinal muscular atrophy (SMA) requires careful trial planning and appropriate outcomes. Traditional tests are fatiguing for SMA infants, use non-linear ordinal scales and require highly trained evaluators to grade movement. Our study provides preliminary reliability and validity data on a video-based assessment, ACTIVE-mini, which uses the Microsoft Kinect to assess infant movement. The infant lies supine and spontaneous movements are recorded using a series of 3D depth map and color images. Algorithms are used to quantify infant movement speed (i.e. velocity, acceleration, and jerk), as well as total movement volume, and the complexity of infant movement within space. Weekly longitudinal and cross-sectional data were collected over 6 months on 6 SMA infants and 30 controls. Movement speed data are plotted as kernel density plots separated in 2-week age-matched bins. Differences are seen in each movement variable in every age bin. On average the SMA infants have an average jerk value of 57.8% of age-matched peers. Tracings of the extremities and the ratio of convex hull’s surface area to volume ratio, where higher numbers indicate decreased ability, illustrate that an SMA infant has a smaller total movement excursion as well as decreased spatial complexity (upper extremity average: 139–170; lower extremity average: 756–891) when compared to age-matched controls (all extremities average range: 43–68). Preliminary results indicate ACTIVE-mini differentiates movement differences related to speed, variability, quantity, and complexity of movement in SMA infants compared to controls in the first 2 weeks of life. ACTIVE-mini has both clinical and research potential to detect movement abnormalities and measure small changes in ability over time. Further research is needed in a larger sample of diverse diagnoses to refine the statistical models of normal movement and identify typical longitudinal changes in infants.