Hello Andrea,
The citations you are making come from the design control portion of the standard so this would apply to verification and validation testing, most would understand during design development, i.e. before design transfer. However, in the existence of working in companies and being exposed to external audits, this does not always apply and can not follow the strictest sense of the standard. For example, often times the design validation is happening in the middle of design transfer or even sometimes after design transfer. In addition, often the manufacturing validation, process validations, product validations, may also occur be occurring around that time as well. The simple answer is statistical rationale applies to all aspects of the device life time, from design and development through manufacturing.
There are expectations in the industry, regardless whether citing specifically from a standard or regulation, if you are doing sampling for the medical device, there should be a rationale/justification for the sample size. If there is verification testing in design where certain specifications are being tested - sampling can be done but needs to be defined and why. During incoming inspection, sampling is performed - needs to define why number is taken. If routine or spot sampling is done in manufacturing, there needs to be the reason and why the sample size is appropriate or sufficient. There are also instances where you can leverage sampling during testing such as in verification you can do a large sample size and validation testing a small sample, or vice versa. In the lifetime of the device, if sampling is performed there should be rationale or justification for the sample size.
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Richard Vincins RAC
Vice President Global Regulatory Affairs
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Original Message:
Sent: 06-Jul-2020 10:03
From: Dan O'Leary
Subject: Rationale for sample size - Verification and validation ISO 13485 requirement
The paragraphs apply to design verification and design validation, which are completed before design transfer.
There is no requirement to use sampling plans. The requirement is that if use one you need to explain why you picked the sample size.
Also recognize that there are other activities with similar names. Process validation, for example, is completed as part of design transfer. Product verification, called product release in 7.5.1.f, is applied through out the production process. Software validation is completed before releasing software or a change.
None of these requiring sampling plans, but, when used, good practice documents the rationale for the sample size and the acceptance criteria.
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Dan O'Leary CQA, CQE
Swanzey NH
United States
Original Message:
Sent: 06-Jul-2020 08:55
From: Andrea Duca
Subject: Rationale for sample size - Verification and validation ISO 13485 requirement
Dear all,
I would like to ask for your opinion about the verification and validation activities carried out by an R&D department, before transfering the design to Production.
Paragraphs 7.3.6 and 7.3.7 of ISO 13485 require that "The organization shall document verification/validation plans that include methods, acceptance criteria and, as appropriate, statistical techniques with rationale for sample size".
Do you think that these statistical techniques with rationale for sample size are applicable only in a manufacturing contest - after the design transfer - or also during the development of the device when some V&V activities are performed?
I am asking this because it is easy to figure out how to handle the final verification of the device, but is not so easy to decide how to handle the V&V activities carried out during the development of the device.
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Andrea Duca
Albano Laziale
Italy
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