Development and usability of a new subcutaneous auto-injector device to administer hydroxyprogesterone caproate to reduce the risk of recurrent preterm birth.

Background: Current administration of hydroxyprogesterone caproate (HPC) by intramuscular injection is associated with limitations, including the potential for human error and contamination, patient anxiety, and increased risk of needlestick injury.

Objective: To describe the design of an auto-injector for subcutaneous (SC) administration of HPC and the results of studies that evaluated the target user's understanding of the proper use of this device.

Materials and methods: A single-use, prefilled, fixed-dose, disposable auto-injector intended for the SC administration of HPC was developed, and its usability by health care providers was evaluated in 3 formative (N=32, 64 injections) and 3 validation studies (N=45, 90 injections). These studies consisted of one-on-one testing sessions performed in a simulated home environment. Analyses were based on observed use error or use difficulty during the performance of specific tasks, including those considered critical (associated with high severity harms).

Results: In the formative studies, the majority of participants correctly administered an injection with the auto-injector, but prior training improved performance. Specific errors were noted, including holding the device at the injection site for a period inconsistent with its instructions for use (IFU). The IFU was modified to reduce potential occurrence of these errors. Use errors were subsequently observed on critical tasks in the first and second validation studies, including hold-time errors that were attributed to using visual cues rather than counting seconds. For the third validation study, the IFU was modified to focus on visual cues and all users were able to successfully perform the injection per the IFU.

Conclusion: An auto-injector device for SC administration of HPC for reduction in risk of recurrent preterm birth was successfully developed through iterative design and validation testing. The device design provides high usability and acceptance of this device by health care professionals.