Medical Device Requirements vs. Specification

There is occasional confusion when discussing what it means to establish "requirements" for a medical device project. The word is so generic that few people agree to its meaning. One thing we have found to be helpful is to define the difference between a requirement and a specification.

We define a requirement as a medical device characteristic that would be described by the end-user or customer. It is typically a general statement of "want" about the product. We define a specification as a "metric" that measures how well that requirement is satisfied.

In an ideal world, each customer requirement would have a single measurable specification. For example, the customer might state that the medical device must be lightweight. The obvious specification (or metric) would be product weight. This is something that we can measure in the lab, compare to a competitive product and track over the course of development.

So a requirement uses customer language and a specification uses engineering language. We'll be discussing four lessons we have learned about requirements in our next posting.