A pen device for injection of recombinant human growth hormone: a European usability engineering study

Figures & data

Figure 1. The three presentations of the pen device (blue: 6 mg; red: 12 mg; yellow: 20 mg).

Table 1. Use scenarios and knowledge tasks.

Evaluation Activities
Use scenario 1: Prepare for and deliver a simulated injection with one cartridge (IFU optional)
Use scenario 2: Prepare for and deliver a simulated injection with multiple cartridges (IFU optional)
Use scenario 3: Prepare for and deliver a simulated injection with one cartridge (IFU required)
Knowledge task 1: Inspection and cartridge matching (IFU interpretation)
Knowledge task 2: Selecting and preparing the injection site (IFU interpretation)
Knowledge task 3: Pen maintenance (IFU interpretation)

IFU: Instructions for use.

Table 2. Participant demographics.

	Pediatric GHD patients and representative GHD patients (n = 8)	Adult GHD patients and representative GHD patients (n = 9)	Healthcare providers (HCPs) (n = 9)
Age (years), mean (range)	15.4 (13–17)	50.7 (32–65)	47.2 (35–62)
Male:female, N (%)	3 (38%):5 (62%)	3 (33%):6 (66%)	4 (44%):5 (66%)
Highest education level, n (%)
School/college	8 (100%)	-	-
Years 9–11	4 (50%)	-	-
Years 12–13	4 (50%)	3 (33%)	-
University	-	4 (44%)	-
Professional/higher degree	-	1 (11%)	-
Other	-	1 (11%)	-
Job title
Physician	-	-	3 (33%)
Nurse	-	-	4 (44%)
Other specialist	-	-	2 (27%)
Injection experience, n (%)	4 (50%)	6 (67%)	-
Years in current job, mean (range)	-	-	15.9 (4–35)
Contact lenses or glasses, n (%)	4 (50%)	4 (44%)	-
Dexterity impairments, n (%)	-	2 (22%)	-

GHD: Growth hormone deficiency. Years 9–11: age 13 to 16 years; Years 12–13: age 16 to 18 years. Dexterity impairments: Arthritis(1 participant); Tremor related to Cushing syndrome (1 participant).

Figure 2. Analysis of overall use errors (related to critical task) with potential for harm.

GHD: Growth hormone deficiency.

Figure 3. Total number of use errors on critical tasks per user group.

GHD: Growth hormone deficiency.

Figure 4. Number of observed errors with potential for harm in scenario 1 and scenario 3.

IFU: Instructions for use.

Table 3. Analysis of the use errors, root causes and action taken.

Use error	Root cause category	Improvement to IFU
User does not wash hands	Clinical practice, IFU/label, multistep process, test artifact	Yes: additional step added into IFU to remind user to wash hands again and take a new cartridge
User does not write the date of first use and expiration date on the dedicated label	IFU/label, multistep process, test artifact	Yes: illustration improved to be more explanatory to the user
User receives cartridge other than Saizen® cartridge	Clinical practice, multistep process, test artifact	No: the label and IFU already emphasize the importance of cartridge inspection
User does not clean the pen as recommended User removes cartridge from pen injector before storing	IFU/label, clinical practice, multistep process, test artifact	Yes: IFU section changed from ‘Storage and maintenance’ to ‘Storing and cleaning’ and instruction moved to a position near procedural instructions
User does not rotate injection site as instructed	Clinical practice, multistep process, test artifact	No: the instruction to do this is already included in the IFU
User does not recognize the wrong Saizen® cartridge has been received	Clinical practice	No: it is not possible to increase the size of this information
User does not set right dose, user does not verify the dose, user does not recheck the dose, user does not adjust an incorrect dose setting	Clinical practice, IFU/label, multistep process	No: instructions on the calculation of the dose are already included in the IFU
User does not identify or distinguish between different doses	Clinical practice, test artifact	No: the dose variants are already clearly explained
User recaps the needle with the inner needle shield	Clinical practice, IFU/label	No: the brand name for each needle is indicated and the size of the illustration could not be increased without detrimental effects for the user
User does not clean injection site	Clinical practice, IFU/label, multistep process, test artifact	No: this would change the normal workflow in the IFU for injection with single cartridges
User does not check goods for damage	Multistep process, test artifact	Yes: additional instruction added ‘Check the cartridge for damage. Do not use if the cartridge is damaged’
User left the pen with attached needle exposed on the table	Clinical practice, multistep process, test artifact	Yes: additional step instruction added to IFU ‘Do not remove cap until ready to inject’
User turns the pen to view the dose window while the needle is still inserted in the skin	Clinical practice, multistep process, test artifact	Yes: improvement made to the related instruction and illustration in the IFU
After priming, the user wipes the droplet with a tissue to remove medication	IFU/label, multistep process	Yes: caution added: ‘Do not wipe the droplet from the needle after priming’
User removes and discards outer needle cap	Clinical practice, multistep process, test artifact	No: this was deemed to be an isolated incident
User might not correctly insert the needle	Clinical practice, test artifact	No: this was deemed to be an isolated incident
User does not understand remaining dose table and does not read the requirements for the table	Clinical practice, IFU/label, multistep process	Yes: changes made to multiple dose calculation table
User cannot unscrew needle	Clinical practice, IFU	No: the cap designs cannot be changed

Clinical practice: Related to the experience of the user with pen devices; IFU: Instructions for use; IFU/label: IFU and/or label need some improvement (i.e., decoupled text instructions); Multistep process: The use of the device requires several steps; Test artifact: Related to simulated-use environment.