Basics of Medical Device Design Controls: What, Why, and How

November 13, 2018
This is the first post in a 3-part blog series on medical device design control. In subsequent post we look at design inputs and outputs, and then DHR, DHF and DMRs. We’ve combined all three posts into one easy-to-read PDF, plus added some extras. Download it here.

Men Working on Engineering Project

Coding changes. Materials substitution. Design refinements. UX improvements. Manufacturing changes.

Medical devices, like all products and software, are constantly evolving. Yet, due to the nature of medical devices and their impact on personal health and safety, the entire product life cycle of a device must be carefully documented. It’s an easy thing to overlook. Developers and engineers get so immersed in the “design and refine” process that they sometimes forget about their obligation to document how they got from A to B.

This documentation process is widely known as “design controls” and its purpose is to ensure that medical devices meet user needs, intended uses, and specified requirements. Design controls apply to the design of the product and associated manufacturing processes. The US FDA has identified lack of design controls as one of the major causes of device recalls, and therefore they want you to pay specific attention to the following:

  • Documenting design procedures and development planning.
  • Identifying design input requirements and developing outputs.
  • Verifying that those outputs meet design inputs.
  • Validating the design (software and/or hardware).
  • Controlling design changes and reviewing design results.
  • Conducting risk analyses and design reviews.
  • Transferring the design to production.
  • Compiling a device history record (DHR), design history file (DHF), and device master record (DMR).

We will talk about each of these things later.

Think of design control as a framework

While design control is not required for all medical devices, it applies to nearly every medium- and high-risk device. And this isn’t just for new devices – in the US, FDA requires design controls for all Class II and III medical devices and even some Class I devices (notable among these are Class I devices automated with software). Likewise, ISO 13485:2016 mandates design controls. We will talk more about the specific requirements of design controls, but it is important to remember that design control requirements are a framework and not a prescriptive solution. Regulators set the expectations but don’t give you the answers. It’s entirely up to you to define your processes, defend them as appropriate, and prove they meet the requirements outlined in the table below.

Design control-related processes in ISO 13485:2016 and FDA 21 CFR 820

Design control-related processes in ISO 13485:2016 and FDA 21 CFR 820

When does design control begin and end?

It never ends. Design control is not a “once and done” process – it applies to modifications or improvements to existing designs, or changes to processes. Design control does not, however, apply to the ideation stage of medical device development. You don’t need to document the development of prototype concepts or feasibility studies. However, you do need to start creating a plan once you have decided that a specific design will be developed. To assist regulators, you should document the flow of the design process so it is very clear where research is ending and development of the chosen design is beginning.

Even if a device has been in the marketplace for years, design control is never really finished. Both large and small changes to a device or associated manufacturing process must be evaluated for their impact on product performance, safety, and use.

The overall design control model

Design Control Elements

Source: US FDA

Setting the stage with design reviews

Design reviews are an important part of the overall design process. The objective is to establish a process to make sure the design you created (the output) meets your design requirements (the input). A design review provides a mechanism that confirms the design is ready to move to the next stage of the process. Although it is technically focused, a design review is not limited to only the design of the product. The resulting analysis provides feedback for the design team. Both FDA and ISO 13485:2016 require you to conduct and document these formal reviews on a regular basis at appropriate stages during the development process. The documented results become a part of the DHF. Those reviews must include representatives from all functions involved in the design process and any other specialist personnel. FDA also requires you to add an independent reviewer without direct responsibility for the design stage being assessed.

The number and types of reviews are project-dependent, so define them in the plan. Review frequency will be impacted by the size and scope of the project and the product development life cycle. At minimum, two design reviews should be held – one at the beginning during the design inputs review process and another at the end during the design transfer phase.

Medical device design control planning

Before you can control your product design, you need a plan for doing so. Design control planning enables the management team to exert more control over the R&D process by clearly communicating policies, procedures, and goals to the development team. It also provides a basis for measuring conformance to quality system objectives. This means you must:

  • Establish documented procedures for design and development.
  • Identify the design and development stages and the development life-cycle model.
  • Identify the activities of development and the deliverables that come from them.
  • Define responsibilities and authorities for executing the activities.
  • Review, update, and approve plans as design and development evolve.

The form and organization of the planning documents are less important than their content and should be customized for each company. Remember that as development progresses, the planning documents should be updated.

Change and configuration management

Product development is inherently an evolutionary process. While change is a healthy and necessary part of product development, quality can only be maintained if those changes are controlled and documented. As such, a key component of design control involves establishing procedures to identify, document, review, verify, validate, and approve design changes before they are implemented. You are not expected to maintain records of all changes proposed during the very early stages of the design process. However, all design changes made after the first design review must be documented. These records create a history of the evolution of the design, which can be useful for failure investigation and for facilitating the design of future similar products. Such records can also prevent repeat errors and the development of unsafe or ineffective designs.

Examples of design changes that must be controlled include:

  • Changes made to the device itself or software
  • Changes in design inputs
  • Labeling or packaging changes
  • Performance changes or changes resulting from complaints
  • Changes that influence previous approved design verification and validation
  • New design criteria added to existing documentation as project milestones are reached

While you are required to document changes, the extent of your evaluation and documentation should be in direct proportion to the significance of the change and its effect on other parts and product in process or already delivered. You’ll also need to establish a system of traceability for this documentation, a process called “configuration management.”  This process involves identifying the documentation to be controlled, the procedures for controlling it, and the responsibilities of those managing the documentation.

Want to learn more about design control for medical devices?

Keep reading. Our second blog post in this series gets into the details surrounding design inputs, outputs, verification, and validation. Also, while reading this series is a great start, you can take your knowledge of design controls to the next level in our intensive design control training class.

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