Background:
Tip-toe behavior (TTB) is showed by about 20% of individuals with ASD and is poorly quantified with structured methods. In a previous study, we proposed a standardized method to quantify TTB during static and dynamic tasks using a video-recording approach in an ecological setting. This testing approach is very time-consuming and operator dependent requiring an operator to review the videos and computing the parameters. To overcome these limitations, an instrumental approach using wearable sensors (WS) and an automated calculation system was developed and applied. Moreover, WS approach would also permit monitoring gait for a longer time during the day.

Objectives:
This study aims at implementing a WS-based protocol for the quantitative assessment of TTB and its validation by the comparison with the reference video-recording approach.

Methods:
Individuals with ASD diagnosed according to DSM-5 criteria and a diagnosis confirmation using the Autism Diagnostic Observation Schedule (ADOS) were involved in the study. TTB was quantified during structured static and dynamic tasks using a video-recording approach, previously described. All the tests were performed without shoes albeit with "Sensoria® Smart Socks". The dynamic test consists in transporting 1 object (e.g. puzzle piece, Lego®) from the therapist to the playing table situated 2 meters away and back again 15 times. The static test consists in playing while standing in front of a table for 3 minutes. Both assessments were repeated on three different days for each individual (9 assessments).
"Sensoria® Smart Socks" (SSS) are the validated WS used during the video-recorded tests. In this way, we were able to collect data obtained from video-recording and WS approaches at the same time. The result of the video-recording and WS approaches were analyzed. The intraclass correlation coefficient (IC) was used to assess the reliability between the video-recording and WS approaches in quantifying the mean percentage of toe steps and the mean percentage of the time spent in ???.

Results:
We assessed 3 individuals with ASD and TTB. The age was 10.9yrs, 12.8yrs and 13yrs (3/3 males) and their ADOS calibrated severity score was 9, 10 and 8, respectively. The normal distribution of data was confirmed (Shapiro-Wilk test p>
0.05). The ICC values of the mean percentage of toe steps and the mean percentage of the time spent in TB were 0.778 (excellent) and 0.731 (good), respectively.

Conclusions:
The "Sensoria® Smart Socks" used for the quantitative assessment of TB in individuals with ASD showed good-to-excellent reliability in comparison with the reference video-recording approach both during a static and dynamic tests.
Further research is required to confirm the results of this preliminary study.

Notes:

1 - Villa Santa Maria Foundation Autism Research Unit, Tavernerio (Como), Italy
2 - Politecnico di Milano, Italy