I worked on a project to develop a needle that when used by the patient “Does not hurt as much”. That was the user requirement. So in order to asses what that meant or how to change that into product requirement the team sat with the medical affairs team and came to an agreement. Pain is associated with nerve simulation. Therefore the needle had to be small enough to penetrate epidermis but barely penetrate the dermis in order to successfully transfer the drug.

So from my experience I would sat that determining the user requirement would need a high level of understanding of the product and the physiology of the body and how the two relate.