Preparing Your Design Controls for FDA Approval

A sound quality management system (QMS) is like the check engine light on your car’s dashboard—it tells you when something is wrong so you can fix it before the engine fails. When preparing your medical device’s QMS for U.S. Food and Drug Administration (FDA) approval, the design controls demonstrate your device meets the needs of the intended user, acting just like the check engine light.

Design controls are a set of procedures to build into medical device design and development (D&D). A system of checks and balances, design controls ensure the product is suitable for its intended use. Putting design controls in place allows you to identify any mismatch between the proposed design and the requirements.

It’s important to create a D&D plan that describes all design activities involved in the project. This is also an opportunity to assign responsibilities across your team and to discuss the plan’s objectives. Additionally, the D&D plan should highlight any major tasks involved and any identify what resources may be required for the device’s development. At this stage, you should classify the device and identify the intended user, such as elderly men or pregnant women.

When manufacturing low-risk, Class I devices, a full QMS is not usually required and therefore, design controls are not necessary. However, when producing Class II devices, like contact lenses and catheters, or more invasive Class III products like pacemakers, it is important to establish these controls early on.

According to the FDA website, there were 32 medical device recalls in 2018 and 49 in 2019. While not every recall was due to errors in pre-production, medical devices are often rejected by notified bodies (NBs) because of a lack of design controls. Failing to update the QMS is another common cause of regulatory failure that can be easily eliminated with best practice when updating design controls.

User Requirements
The first step in medical device design is establishing the user requirements of a device. You can get this information from customer surveys, complaints, and feedback from physicians. You can also create a user-device system to understand the ways people interpret information from the device, and how they interact with it. The key here is understanding the alarms and interfaces needed and whether the operator requires training to use the device.

User needs are then fed into the design inputs, which detail the device’s various requirements, including functional needs around what the device should do and performance requirements on how well it should operate. The design inputs should also include interface requirements that specify any characteristics needed to make it easy for patients to use.

It’s important to create design input requirements that are as clear as possible. If they are ambiguous, they can be open to interpretation and difficult to verify. I have seen many companies make convoluted requirements for their devices that cannot be proven with any certainty; this always holds them back.

Unless rectified, ambiguity can throw your design controls into doubt and undermine the QMS. This often comes down to how manufacturers define their concepts. For example, if a manufacturer claims a scalpel “must be sharp,” they will be unable to prove this requirement has been met because it isn’t clear what they need the device to do. By instead saying the scalpel “must be sufficient to cut flesh seamlessly,” this provides a way of verifying its effectiveness.

The Importance of Traceability
Once you have generated the design outputs, it is important to trace them to the original input requirements. This can help you demonstrate the device meets the needs of the user and the product does what is required of it. You can then document the design review in the Design History File (DHF) along with any information on design verification. You can also record any instructions, drawings, and records in the Device Master Record (DMR).

A great way to ensure traceability is by creating a traceability matrix—the design inputs and outputs listed in a tabular format. In the matrix, you specify a corresponding output for each design input. For instance, if the input is that the scalpel must be sharp enough to effortlessly cut through human flesh, the output would be that it must be sharp enough to pass a verified sharpness test. While it isn’t an FDA requirement, building a traceability matrix is good practice because it demonstrates the evolution of a medical device from start to finish.

From a risk management perspective, traceability between design inputs and outputs can help you detect any possibility the device will fail. By mapping out the various stages of the device’s production, you can understand where the problem is so you can fix it. If you don’t have in-house knowledge of FDA requirements, you can hire a freelance FDA compliance consultant to ensure traceability in your design controls.

Like the check engine light in your car, design controls and a robust QMS can help you predict issues early on and highlight them so they can be rectified to prevent more serious problems. Design controls create a traceable map that links user needs to the final design of the device, ensuring it is both effective and suitable for its intended users.

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Adam Freeman performed inspections and premarket approvals for FDA for seven and a half years and is now a senior consultant operating out of Switzerland. He operates as a coach assisting with market clearance, internal audits, mock inspections, design, manufacturing, validation, and compliance.