Design Verification Process for Medical Devices: All You Need To Know

The verification process is an evaluative procedure for checking whether the design of a medical device meets the applicable requirements or not. It includes any activity that can provide proof that the legal requirements are being fulfilled. More specifically, it helps manufacturers and verification specialists check that the medical device design is on track and that what has been designed (i.e. design outputs such as engineering drawings and prototypes or risk analysis results) meets its requirements (i.e. design inputs).

Verification of device design is needed in any of the following cases:

• When the design of a ‘new’ medical device has minor changes – e.g. cosmetic or comprise minor technical improvements;
• When the new device has a simple design and it is judged to present a low safety risk;
• The medical device entering the market has a notably innovative and complex design.

If performed correctly, manufacturers can minimise the commercial risks, the compliance costs and the risks to users. However, if the process is performed poorly, then the project costs will rise, the sales revenue decrease and the company may be exposed to negligence claims. The negligence claims can occur as a result of, for example:

• Failure to gain regulatory approval
• Project inefficiencies
• Loss of company image
• In-market device modifications
• Recalls
• User injuries and deaths
• Liability and litigation.

To be carried out, the verification process requires the presence of three elements:

• A model (the medical device design) – it represents the part of the design that will be evaluated;
• A requirement – it specifies what the model that to achieve;
• A method – it defines how the verification process is to be performed and it is normally specified in the verification protocol. The choice of the verification method depends a lot on factors such as development risks, support risks, knowledge about the device in question, and the degree of novelty and complexity of the device.

All three elements are linked together as shown in the figure above. Therefore, if there is a change in one of them, the other elements may also need to change in some way. For instance, if the requirements are specified incorrectly, then the associated verification activities may need to be repeated or modified accordingly, which will consequently add costs and delay to the project.

The verification process is usually carried out multiple times and in various ways throughout the development of the medical device. It is rarely performed just once at the end of the design process. Therefore, it is a good practice to divide the verification activities into two groups as each has different objectives:

• Regular verification – this type of verification occurs as the device design progresses, and it aims at minimising risks by providing satisfactory assurance that the design in development meets its requirements. The activities part of the regular verification can be separated into spontaneous (e.g. casting an eye over the device design and then basing decisions on experience or gut feeling) and significant (e.g. tensile strength testing and finite element analysis).
• Final verification – it provides the ultimate proof that the design of the medical device meets the requirements. It occurs at the end of the design process and may require the employment of a more costly but more accurate verification method.

Verification, as a process, is influenced a lot by two factors: the likelihood of a failure and the effects of that failure. Therefore, to be performed correctly, it must be followed a risk-based approach, so that at the end the process is completed through a combination of product re-design, which can mitigate the risks, and verification, which can lower the uncertainty level. Following such an approach can help fine-tune the verification-related action and gain the benefits of good verification practice. 

To implement a good verification practice, which timing and quality are appropriate from a commercial and regulatory point of view, the following 3 stages need to be carried out:

1. Outline verification plan: It should be determined when verification should occur and outlined what verification methods should be followed.
2. Improvement of the verification plan: Manufacturers have to determine the details of each method that will be used during the verification process and fine-tune the timing of the regular verification activities
3. Execution of protocols: All protocols have to be checked before being executed and then the verification results to be recorded.

It is likely that all three stages stated above will need to be repeated regularly during the medical device’s design process. Stage I is usually repeated when new regulatory requirements are introduced or old ones changed, while stage II is regularly repeated throughout the design process for each protocol. Stages III runs when the design process is close to its end.

In the figure below, a detailed overview of the verification process is presented.

 Problems that occur during verification are often caused by changes to any of the three verification elements. For example, the introduction of a new standard may result in the need to change the device design, consequently leading to project delays and overspend. For managing changes during the design verification process, two types of review may be used:

• Before carrying out key verification activities – considerations about the likelihood and severity of any upcoming changes should be taken, as they may require the verification process to be repeated;
• When a change occurs – reviewing the relevant verification elements may help determine the effects of the change.

All verification-related activities must be documented, as the objective is to complement any existing company documentation that contains information about undertaken procedures and regulatory and quality system requirements. Documenting the verification process can also be helpful for a variety of reasons, such as helping with liability protection, carrying out an efficient design and development process, etc. However, the degree to which the documentation is required may differ, depending on the pre- and post-market risks, company procedures, regulatory and quality system requirements. The verification documentation can be in the form of:

• Plans - contain references (e.g. a summary of the technical documentation for demonstrating compliance with the legal requirements) as to when each verification is projected to be carried out during the device design process.
• Protocols - include information about the verification scope, requirements, acceptability criteria, model characteristics, verification method and references to standard methods (standards used to stipulate the verification method).
• Results and conclusions - e.g. verification results and their analysis, conclusions and declaration of conformity.

To conclude this post, to manage and keep track of the verification process and know where it has yet to be carried out, manufacturers or specialists in charge can use a traceability matrix or appropriate computer tools.