Medical device product development teams often think they need to have all the customer requirements and design inputs defined when they enter design controls. In this posting, I’ll explain to you why it isn’t necessary to have them completely defined upfront and ways to add more detail over time. In our experience, we find teams spending months debating requirements, when they do not have sufficient information to define the design inputs at anything but at the highest level. This is particularly true for complex medical devices with multiple components and/or layers of sub-assemblies.
The regulators expect the major customer needs to be defined and the high level design inputs to be identified, as well as major and often unstated requirements (such as the product meets environmental requirements or the product can be serviced) when entering design controls. The regulators expect the design inputs to evolve as the product is developed. All other requirements may be developed or iterated as more information is gained during development.
Below are some steps to help you get those requirements in place more quickly.
- Develop a list of critical customer needs. These are the “must haves” to distinguish your product in the market and support your value proposition. If there are changes in the market, these may need to be adjusted. Frequently, these are defined using qualitative language (e.g., easy to use, soft, lightweight, long battery life, etc.)
- Translate the critical customer needs into design inputs at the highest or system level, using broad ranges or using a wide range which includes a minimum or maximum value. Use any information collected from early market feedback or models to help establish that information. For example, product weight will be no more than 8 oz. or MVTR will be 3-5 gm/m2/day.
- When applicable, add any backwards compatibility requirements.
- When standards apply, refer to the standard rather than creating new requirements from scratch. For example, the product will meet the requirements of ISO 60601. You can then use a separate form to assess which sections of the standard are applicable to your product.
- Add unstated customer needs, which are necessary to sell your product.
HINT 1: Generate a library of design inputs that are commonly used for your product type. These are often based on environmental, health and safety, countries of launch, packaging, labeling, country specific standards, operations, service, installation, reimbursement (if it applies to your product type), regulatory, sterility, human factors, etc. Use these as a starting point for the unstated requirements, but let the product development team select the ones to use based on the product.
HINT 2: Ensure your process includes a method to designate business related requirements (e.g., scrap rate, margins, product cost) that may be easily changed.
- Sign off the top level requirements.
- If not already done, define the product architecture. Then modify the design inputs based on this information. As you decompose the product into the lower levels, define the needed requirements.
- Collect information on the product from customers and internal testing. This may be in the form of models, mockups, subassemblies, or preliminary designs. Document the learnings. Analyze for real changes to the requirements. Based on this information, modify the design inputs. They may become more precise or tighter as you gain additional information.
- Iterate as needed during product development.
- Changes after design freeze should be limited.
Defining the design inputs for a new product is very important to developing the right medical device product. However, you may not have enough information to create very detailed requirements prior to entering design controls. In those situations, start with the major customer needs, create high level design inputs, then iterate as more information is available.