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Evaluation of performance, acceptance, and compliance of an auto-injector in healthy and rheumatoid arthritic subjects measured by a motion capture system

Authors Xiao X, Li W, Clawson C, Karvani D, Sondag P, Hahn JK

Received 20 December 2017

Accepted for publication 17 January 2018

Published 9 April 2018 Volume 2018:12 Pages 515—526


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Dr Johnny Chen

Xiao Xiao,1 Wei Li,1 Corbin Clawson,2 David Karvani,2 Perceval Sondag,3 James K Hahn1,4

1Department of Computer Science, The George Washington University, Washington, DC, 2MedImmune, LLC, Gaithersburg, MD, 3Arlenda, Inc., Flemington, NJ, 4Department of Pediatrics, The George Washington University, Washington, DC, USA

Purpose: The study aimed to develop a motion capture system that can track, visualize, and analyze the entire performance of self-injection with the auto-injector.
Methods: Each of nine healthy subjects and 29 rheumatoid arthritic (RA) patients with different degrees of hand disability performed two simulated injections into an injection pad while six degrees of freedom (DOF) motions of the auto-injector and the injection pad were captured. We quantitatively measured the performance of the injection by calculating needle displacement from the motion trajectories. The max, mean, and SD of needle displacement were analyzed. Assessments of device acceptance and usability were evaluated by a survey questionnaire and independent observations of compliance with the device instruction for use (IFU).
Results: A total of 80 simulated injections were performed. Our results showed a similar level of performance among all the subjects with slightly larger, but not statistically significant, needle displacement in the RA group. In particular, no significant effects regarding previous experience in self-injection, grip method, pain in hand, and Cochin score in the RA group were found to have an impact on the mean needle displacement. Moreover, the analysis of needle displacement for different durations of injections indicated that most of the subjects reached their personal maximum displacement in 15 seconds and remained steady or exhibited a small amount of increase from 15 to 60 seconds. Device acceptance was high for most of the questions (ie, >4; >80%) based on a 0–5-point scale or percentage of acceptance. The overall compliance with the device IFU was high for the first injection (96.05%) and reached 98.02% for the second injection.
Conclusion: We demonstrated the feasibility of tracking the motions of injection to measure the performance of simulated self-injection. The comparisons of needle displacement showed that even RA patients with severe hand disability could properly perform self-injection with this auto-injector at a similar level with the healthy subjects. Finally, the observed high device acceptance and compliance with device IFU suggest that the system is convenient and easy to use.

Keywords: subcutaneous injection, auto-injection, motion tracking, hand disability, rheumatoid arthritis, Cochin score

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