Wearability, Saefty and Usability Assessment for the Upper Limb Exoskeleton BRIDGE/EMPATIA

The PUL includes 22 items with an entry item to define the starting functional level and 21 items subdivided into shoulder level (4 items), middle level (9 items) and distal level (8 items). For weaker patients, a low score on the entry item means high-level items do not need to be performed. Each dimension can be scored separately with a maximum score of 16 for the shoulder level, 34 for the middle level and 24 for the distal level. A total score can be achieved by adding the three level scores, with a maximum global score of 74. The lower the score, the higher the disability.

Pane et al., Reliability of the Performance of Upper Limb assessment in Duchenne muscular dystrophy, Neuromuscular disorders 2014, 24:201-206.

Self-administered questionnaire aimed at measuring manual ability in daily life. Patients are asked to answer 14 questions plus 4 items differentiated with respect to the age of participant (older or younger than 15 years). Overall, the Abilhand questionnaire has 22 items. For each item, the participant has to answer if the presented action is "impossible", "difficult" or "easy" to be performed in his/her opinion. A three-level scale is used to calculate a total score according to the answer given: "impossible" (0 points), "difficult" (1 point) and "easy" (2 points). The higher the score, the easier the perception of self-ability. Data are converted to a probabilistic model through the Rasch model, which estimates the item difficulty and a patient's manual ability on a standard linear scale, within a probabilistic framework.

Penta et al., ABILHAND: a Rasch-built measure of manual ability, Archives of Physical Medicine and Rehabilitation 1998, 79:1038-1042.

The technology acceptance model (TAM) is an information systems theory that models how users come to accept and use a technology. A dedicated TAM has been developed, and administered to the patients in the form of 26 questions on the evaluation of different aspects of the device (e.g., saefty, confort, etc.). For each item, the patient has to provide a score from 1 to 5, where 1 is completely disagree and 5 is completely agree. The higher the score, the better the technology acceptance.

It is a ten-items scale giving a global view of subjective assessments of usefulness as a combination of effectiveness, efficiency, and satisfaction. Each item score contribution ranged from 1 to 5. For items 1, 3, 5, 7 and 9 (the positively worded items) the score contribution was the scale position given by the subject minus 1. For items 2, 4, 6, 8 and 10 (the negatively worded items), the contribution was equal to 5 minus the scale position. Then, the scores were summed and multiplied by 2.5 to obtain the overall value of SUS. Scores can range from 0 to 100. SUS is evaluated according to Bangor research guidelines (Bangor et al., An Empirical Evaluation of the System Usability Scale, International Journal of Human-Computer Interaction, 2008, 24:574-594): scores in the ranges [55, 75], [75.1, 87.5] and [87.6, 100] indicated respectively "good", "excellent" and "very excellent".

Brooke, SUS - A quick and dirty usability scale, Usability evaluation in industry, 1996, 194:4-7.