Evolution of the RebiSmart^® Electromechanical Autoinjector to Improve Usability in Support of Adherence to Subcutaneous Interferon Beta-1a Therapy for People Living with Multiple Sclerosis

Figures & data

Figure 1 The RebiSmart^® 3.0 device is an electromechanical autoinjector to administer subcutaneous interferon beta-1a (Rebif^®) for the treatment of patients with multiple sclerosis.

Figure 2 Strengths and opportunities for improvement of the prototype device.

Table 1 Key Use Errors During Use Scenarios (Summative Usability Study)

Task	Incidences of Use Errors^a,b (n)	Findings	Root Causes	Outcome
Use scenario: Administer injection
Inspect new cartridge	39	Did not inspect new cartridge for particular aspects (ie, medication name, dose strength, integrity, damage)	Did not check because of study simulated environment; not usual habit to check aspects	On-screen text updated to remind user; training reinforced
Wash hands	34	Did not wash hands	Reliance on participant to develop habit; participant perceived hands to be clean because of the simulated environment	Training reinforced to remind user
Disinfect injection site	30	Did not disinfect the injection site	Disinfecting the injection site is not common practice in the UK; simulated environment	Training reinforced to remind user
Dispose of old cartridge	10	Did not dispose of cartridge appropriately	Confusion between cartridge (non-sharp) and sharps containers	Training reinforced to remind user
Use scenario: View injection history
Check injection history	21	Did not check injection history completely	Inconspicuous scroll bar; unclear meaning of dose symbols	Training reinforced to remind user

Notes: ^aIncidences ≥10 are illustrated.^bIncidences reported represent the combined total of use errors. Some duplication of use errors occurred due to the overlap of critical tasks.

Table 2 Use Errors with Knowledge Tasks Related to Safe Use of the Device (Summative Usability Study)

	Incidences of Use Errors^a (n)		Findings	Root Causes	Outcome
Knowledge task 1	Knowledge check	IFU reading comprehension
Inspect cartridge	36	9	Did not state to check the packaging and cartridge label for medication name, dose, signs of damage, and expiration date	Habit – would not check certain aspects of the cartridge	Information added to on-screen text to remind user to inspect cartridge
Dropped cartridge	25	6	Did not state to remove and inspect the cartridge if it is not visibly broken from the outside of the autoinjector	Reliance on prior knowledge; habit – own injection practices differ from IFU	Training notes updated to remind trainer to inform user to check IFU
Retrieve needle	23	8	Did not state check the needle’s expiration date, nor to check the sterility seal for damage	Reliance on prior knowledge; habit – own injection practices differ from IFU	Training notes updated to remind trainer to inform user that needle has expiration date
Determine injection site	19	3	Did not state that their HCP would advise on the correct injection site; participants stated they would use the rotation guide to determine the correct injection site	Presence of rotation guide; habit – own injection practices differ from IFU	None required as users will receive training from their HCP on correct injection site
Issue with device (eg, device is dirty)	20	1	Did not state success criteria; confusion between antibacterial/alcohol wipe and soap	Perception of required sterility; habit – own injection practices differ from IFU	Training notes updated to remind trainer to advise of cleaning the device
Knowledge task 2	Screen reading comprehension
Unknown cartridge status (more than 28 days)	15		Did not state that they should remove the cartridge if it was first used more than 28 days ago	Message inconsistent with cartridge recognition features; ambiguous required action	Information added to on-screen text to remind users
Needle detachment failure	14		Unable to state correct procedure to detach needle	Ambiguous phrasing	The IFU supports users to follow on-screen instructions
Needle attached at power on	13		Unable to interpret message	Unclear phrasing	On-screen prompts to be acknowledged by user before proceeding
Select site (inject a recently selected site is not recommended)	10		Stated to proceed with chosen recommended site	Ambiguous phrasing; participants expected a site to be automatically recommended	On-screen text updated to improve readability
Titration schedule not complete	10		Did not understand the word “titration”	Unfamiliar terminology	Users that require titration schedule will have received training

Note: ^aIncidences ≥10 are illustrated.

Abbreviations: HCP, healthcare professional; IFU, instructions for use.

Table 3 Summary of User Needs Findings (Summative Usability Study)

User Need (Interview Question)		Average Rating of Participants’ Scores (1 = Lowest Score, 5 = Highest Score)
Gender-neutral device (Device perceived to be gender neutral)	Male	4.8
	Female	5.0
Set injection speed and depth (Ease of changing injection settings)		4.8
Customize device (Ease of customizing volume)		4.7
Storage case accommodates symptoms without stigmatization (Ability to accommodate symptoms)		4.5
Comfort with taking device out in public		4.1
Customize device (Ease of customizing color)		4.0
Device not perceived to remind me of my disease		3.9
Carrying device when travelling, and compact storage case (Ease of device and storage case for travel)		3.7
Device does not look like a medical product		3.2
Device accommodates symptoms without stigmatization^a (Device places a negative focus on symptoms)		1.4

Notes: ^aRating: 1 = no negative focus at all, 5 = very negative focus.

Figure 3 Percentage of participants providing the highest rating in the individual user needs survey (summative usability study).

Table 4 Summary of Feedback Statements Findings (Summative Usability Study)

Functionality (Feedback Statement)	Average Rating by Participants (1 = Strongly Disagree, 5 = Strongly Agree)	Participants Providing Highest Rating n/N (%)
Use confidence (Comfortable with self-use)	4.9	35/40 (88)
Smartphone comparison (Device is as easy as a smartphone)	4.7	28/37 (76)
Smartphone comparison (Device resembles a smartphone)	4.5	24/39 (62)
Injection stability (Injection button allows stable injections)	4.5	27/40 (68)

Table 5 Summary of Feedback Statements Findings According to Prior Experience with the RebiSmart Electromechanical Autoinjector (Summative Usability Study)

Functionality (Feedback Statement)	Average Rating by Participants (1 = Strongly Disagree, 5 = Strongly Agree)
	RebiSmart-Experienced	RebiSmart-Naïve
Battery (Rechargeable battery is environmentally friendly)	4.9	4.1
Usability (Device is easy to use)	4.6	–
Data transmission (Transmitting data is easy)	4.6	4.6
Device weight (Device is light and easy to handle)	4.5	3.9
Position injection button (Button position allows easy injections)	4.4	4.6
Device volume level (Device is quiet)	4.2	4.1
Robustness (Device is robust)	3.4	4.5

Figure 4 Percentage of participants providing the highest rating of the individual feedback statements, according to prior experience of the RebiSmart^® electromechanical autoinjector (summative usability study). *Considered by RebiSmart^®-experienced participants only, in comparison to RebiSmart^® 2.0.