What’s the difference between verification and validation?
Verification and validation, also called V&V, are essential parts of the design process. Verification is establishing that a design output meets a design input - this is like asking the question “did I build the product correctly?” Verification needs a measurable acceptance criteria Validation is establishing that a design output meets the intended use of the device - this is like asking “did I build the correct product?” Validation is more subjective, and hence requires more input from users to ensure it meets their expectations.
As an example, think of a surgical scalpel. A design input, which could be based on things like requests from customers, previous experience in the industry, or other stakeholder input, would be a specific blade length. A design verification test would then be a measurement of the blade length to ensure it is within specifications. Using this same example, the intended use of the surgical scalpel would be something like “the scalpel must cut through tissue cleanly x amount of times before it needs to be discarded or sharpened.” A validation test to ensure that the scalpel meets this need would require cutting simulated tissue and evaluating it according to some specified acceptance criteria.
Do you always need clinical testing?
In general, you need to prove that your medical device is safe and effective for its intended use - and V&V testing is an important part of that requirement. However, you don’t always need to test your product on patients before regulatory approval. This depends on the regulatory pathway of your device. For some devices, there are established performance criteria and already-cleared devices that can serve as predicates. In these cases, developers can test their devices against another device instead of involving patients. The regulatory body will determine if your substantial equivalence is appropriate during a pre-sub meeting. You can learn more about pre-sub meetings here. (BGP-13)
What are the steps for verification and validation testing?
The most important thing to do before verification and validation can begin is creating a verification and validation plan (V&V plan). A V&V plan outlines the steps for performing verification and validation testing, including identifying which requirements are verified by which verification test and which user needs are validated by which validation test. The V&V plan also includes the test protocols, acceptance criteria, and other elements that will be included in the V&V report, which is the output from V&V testing.
Once the V&V plan has been developed, the test protocols can be executed. For medical devices, it’s important that all test protocols and reports are controlled using Good Documentation Practices (GDP). Test results should be clearly interpretable based on the acceptance criteria, which are determined before the testing is executed. Finally, a report is created based on results of the performed testing. Test failures should be documented and investigated - a product is not ready for design freeze if there are failures in V&V testing. If all V&V testing is passed, the design can be frozen.
