Needle Usability Study

@ HFCSI

This was an evaluative research project I supported at HFCSI. The high-level objective of the study was to explore the behavior and attitudes of users interacting with an injection device syringe and needle to evaluate its safety and usability during a simulated self-injection. Some of the information displayed is removed or modified due to confidentiality.

I was brought in to support the research team by moderating sessions, and contributing in: development of the study guide, analysis of data, synthesizing insights, and writing of the final report.

Background and Goals

The client needed evidence from research to determine whether the implementation of a new needle design mitigated persisting needle-specific problems during simulated user self-injection observed in previous studies. Some key goals we had include:

  • Evaluate the effectiveness of user interactions in safely handling the needle with the syringe during safety-critical steps in the injection process.

  • Determine whether the information provided in the instructions for use (IFU) provide clear information about how to perform the injection.

  • Identify any new or remaining non-safety critical issues associated with the handling of the needle with the syringe.

Figure 1. Safety-critical tasks

Challenges

A few challenges needed to be addressed included:

  • Small user population. Surrogate participants with similar disease condition were recruited instead of the actual intended population to avoid issues recruiting intended participants for relevant future studies.

  • Limited device availability. Research team relied on instructional videos and device documentation to understand devices functionality during study planning stage because the available number of devices was limited and reserved for participants.

  • Device with exposed needle. Research team had to develop a contingency plan and discuss strategies to act during potential accidental participant needle poking, as a result of the device having a real, exposed needle.

Method

The achieve these goals, we collected behavioral and attitudinal data from surrogate users. We conducted a round of formative usability testing with 18 participants divided in 9 with previous injection experience and 9 without previous injection experience, which allowed us to have direct observation of our surrogate users. We also conducted a root cause analysis with each participant to understand the reasoning behind some of the observations captured while they were handling the syringe and needle.

Figure 2. Behavioral results

Crucial Insights

The physical design of the device (needle system) failed to support the correct removal of the needle case protecting the needle.

Removal of the case protecting the needle led to some users pulling the safety mechanism and locking the needle accidentally. As users attempt to pull from the case, they also grab onto the locking mechanism and inadvertently activate it. The user’s mental model led them to hold the needle case from the base, which is substantially close to where the locking mechanism is located.

Physical appearance of the needle failed to support user confidence in the device

Length of the needle is on the longer end of the spectrum for subcutaneous needles, causing some users to stated that they were not completely comfortable with it. Some injection experienced users stated their previous syringes had shorter needles.

Additionally, the needle’s manual locking mechanism is made from a thin translucid plastic material, which users considered to be too “flimsy” for its purpose, making them question whether the device would break if not handled carefully.

For additional findings and learnings, please contact david_ha_08@hotmail.com

Figure 3. Design insight

Research Impact

Strategic Impact

  • The client decided to pivot, replacing the original needle and adopting the new needle variation, focusing their resources on other aspects of the product development process.

Tactical Impact

  • The client will conduct an additional study to introduce slight design changes to the new needle variation with the goal of mitigating use problems associated with the needle case removal and appearance of the needle.

Figure 4. Design insight

My Learnings

  • it is important to understand which are the best and most realistic design recommendations given the specific situation, as different stakeholders have different needs and constraints.

  • Mentoring of junior co-worker in how to moderate and conduct root-cause analysis.

  • Iterative research is important! The earlier you find issues the easiest it is to mitigate it!