Presentation
MDD28 - User Force Acceptance for Prefilled Syringes
DescriptionIntroduction
Prefilled syringes (PFS) are one of the most used devices to subcutaneously administer medications. Understanding user injection force acceptance for PFS can help inform decisions regarding medication concentrations, device presentations, and intended user groups. To keep medication volumes reasonable for subcutaneous injections (~ 1-2 mL), medications are formulated at high concentrations thereby increasing their viscosity. The increased viscosity requires higher injection forces to inject these medications subcutaneously. Ease of use is especially important for patient populations where the disease negatively affects hand function, e.g., rheumatoid arthritis, or for those with age-related functional decline. As a result, higher PFS injection forces may be unacceptable to users.
Methods
A formative HF study was conducted with injection experienced (n=13) and injection naïve (n=12) Crohn’s disease and ulcerative colitis patients to understand user acceptance of injection forces associated with PFS. The study utilized solutions with 27.7 cP and 24.5 cP. Each PFS contained a 2-mL fill of one of the two different viscosity solutions. Participants simulated up to two injections with each viscosity solution into injection pads (up to 4 injections total per participant).
Objective data measured included the injection force and time. These were measured using a customized instrumented system that includes a force sensor attached to the plunger head.
Subjective measures included self-reported data regarding the acceptability, ease of use and comfort during simulated injections using an ordinal Likert scale as well as workload assessment tools such as the Borg Rating of Perceived Exertion (RPE) scale and the physical demand and effort dimensions from the NASA Task Load Index. Open ended feedback on the injections experience was also collected.
Results
• Despite participants delivering nearly all the injections successfully (95 out of 97), the force required to inject solution from the PFS was regarded negatively by many participants regardless of solution viscosity.
o The majority of participants made at least one negative comment about the force required to inject using the PFS (18 out of 25 participants made a negative comment about at least one injection they performed), which raises concerns regarding meeting intended user needs and potential complaints for an on-market PFS if it were to contain a similar viscosity solution.
o Similarly, participants exhibited signs of physical struggle while completing the simulated injections, including actions such as squinting their eyes, furrowing their eyebrows, and flaring their elbows out to try and generate more inline force. The moderator also observed tensed hands, shaking thumbs from pressing hard, and an exaggerated exhale.
• Likert scale acceptability ratings sometimes contradicted observed use difficulty and subjective feedback during simulated use (i.e., the subjective data can be ‘noisy’).
• Higher injection forces are generally associated with shorter injection times. In this study, participants moderated the injection force in a variety of ways, including giving the injection over longer periods of time (e.g., above 15 seconds), or starting and stopping application of force to the plunger multiple times. Instructions for use associated with the PFS can advise users on the relationship between injection speed and required injection force to manage users’ expectations around the injection force and time.
Prefilled syringes (PFS) are one of the most used devices to subcutaneously administer medications. Understanding user injection force acceptance for PFS can help inform decisions regarding medication concentrations, device presentations, and intended user groups. To keep medication volumes reasonable for subcutaneous injections (~ 1-2 mL), medications are formulated at high concentrations thereby increasing their viscosity. The increased viscosity requires higher injection forces to inject these medications subcutaneously. Ease of use is especially important for patient populations where the disease negatively affects hand function, e.g., rheumatoid arthritis, or for those with age-related functional decline. As a result, higher PFS injection forces may be unacceptable to users.
Methods
A formative HF study was conducted with injection experienced (n=13) and injection naïve (n=12) Crohn’s disease and ulcerative colitis patients to understand user acceptance of injection forces associated with PFS. The study utilized solutions with 27.7 cP and 24.5 cP. Each PFS contained a 2-mL fill of one of the two different viscosity solutions. Participants simulated up to two injections with each viscosity solution into injection pads (up to 4 injections total per participant).
Objective data measured included the injection force and time. These were measured using a customized instrumented system that includes a force sensor attached to the plunger head.
Subjective measures included self-reported data regarding the acceptability, ease of use and comfort during simulated injections using an ordinal Likert scale as well as workload assessment tools such as the Borg Rating of Perceived Exertion (RPE) scale and the physical demand and effort dimensions from the NASA Task Load Index. Open ended feedback on the injections experience was also collected.
Results
• Despite participants delivering nearly all the injections successfully (95 out of 97), the force required to inject solution from the PFS was regarded negatively by many participants regardless of solution viscosity.
o The majority of participants made at least one negative comment about the force required to inject using the PFS (18 out of 25 participants made a negative comment about at least one injection they performed), which raises concerns regarding meeting intended user needs and potential complaints for an on-market PFS if it were to contain a similar viscosity solution.
o Similarly, participants exhibited signs of physical struggle while completing the simulated injections, including actions such as squinting their eyes, furrowing their eyebrows, and flaring their elbows out to try and generate more inline force. The moderator also observed tensed hands, shaking thumbs from pressing hard, and an exaggerated exhale.
• Likert scale acceptability ratings sometimes contradicted observed use difficulty and subjective feedback during simulated use (i.e., the subjective data can be ‘noisy’).
• Higher injection forces are generally associated with shorter injection times. In this study, participants moderated the injection force in a variety of ways, including giving the injection over longer periods of time (e.g., above 15 seconds), or starting and stopping application of force to the plunger multiple times. Instructions for use associated with the PFS can advise users on the relationship between injection speed and required injection force to manage users’ expectations around the injection force and time.
Event Type
Poster Presentation
TimeTuesday, March 264:45pm - 6:15pm CDT
LocationSalon C
Digital Health
Simulation and Education
Hospital Environments
Medical and Drug Delivery Devices
Patient Safety Research and Initiatives