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  • 1.  Hazard Analysis for SaMD

    Posted 05-Jul-2022 21:12
    Hi Folks

    What does everyone think is, or are, the best Hazard Analysis Tools for SaMD?

     Or which ones (PHA, FMEA, HAZOP etc.) are the best ones to use at different stages in different Software Lifecycle stages?

     Many thanks
     Paul

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    Paul Campbell
    Clinical Director
    Glasgow
    United Kingdom
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  • 2.  RE: Hazard Analysis for SaMD

    Posted 06-Jul-2022 07:08
    Hello Paul,

    You will probably find a wide variety of responses to your query as there are quite differing opinions and ways risk management tools are applied.  This is my own personal thoughts, so will disclaim this first haha.  Definitely a hazard analysis would be performed as this can be from a top down view of the software - though even hazard analysis can be done a few different ways.  You can do a FMEA for a Software as Medical Device (SaMD) though it is not really quite effective because FMEA is a "bottom up" approach and often software is viewed as having no probability of occurrence - though probability of occurrence can be related to the harm according to the standard.  Again there are different ways this can be done and will find differing ways this is applied or interpreted by people.  Myself personally, I use a modified version of a typical hazard analysis structure which has been tailored over the years developed for software in medical devices and SaMD.  This takes an approach of more a hazard analysis and Failure Tree Analysis (FTA) as a "top down" approach which have found is more appropriate for software.

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    Richard Vincins ASQ-CQA, MTOPRA, RAC
    Vice President Global Regulatory Affairs
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  • 3.  RE: Hazard Analysis for SaMD

    Posted 07-Jul-2022 11:58
    Paul and group,

    Happy to step in here with some clarification.  First of all as FDA recognized in the Preamble to 21 CFR 820, the proper term is "risk analysis".  FDA stated in the Preamble, I think it was Comment 83, that risk analysis is the proper term to use.  After all, we are analyzing the risk and not the hazard in the ISO 14971 process.  

    I have a couple of references for you that give a proper framework to your question.  The first is GHTF Risk Guidance which is still in use though a 2005 document.  I refer to it for an example of documenting risk management activities as shown in Annex C.

    The second reference is directed related to software and that is the bridge document between IEC 62304 medical device software standard, and ISO 14971 risk management standard.  The document I refer to here is IEC TR 80002-1 and it explains how risk management and software are to work together.  It is a very useful document that explains the relationship between the two processes and provides some useful examples.

    There were some discussions of FMEA here, and this tool can be used within its limitations, to provide some information on hazards that are then analyzed in the ISO 14971:2019 risk analysis process (Clause 5).  FMEA requires design outputs be created to perform its analysis, and this is a major limitation as it comes late in the design process.  Another major limitation which conflicts with ISO 14971 risk analysis and that is the fact that FMEA is a single-fault tool.  14971 requires you analyze all faults.  A more proper tool may be Fault Tree Analysis (FTA) which actually came from he software world.  FTA allows you to look at all sources of the hazard not just single-fault.  FMEA was designed as a reliability tool, and not for performing risk analysis, but it can help in the late stages of design to see if you may have overlooked a single-fault hazard.  I know Dan and I could provide a lot more information on FMEA, but that is not the purpose of my response here.

    Get the documents i referred to above, the GHTF is a free document at the IMDRF webpage, but you will have to buy IEC TR 80002-1 from your standards supplier.  It should help you understand how to connect software development and risk management.

    Hope you find hit helpful.

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    Edwin Bills MEd, CQA, RAC, BSc, CQE, ASQ
    Principal Consultant
    Member, ISO TC 210 JWG1 Risk Management
    Overland Park KS
    United States
    elb@edwinbillsconsultant.com
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  • 4.  RE: Hazard Analysis for SaMD

    Posted 06-Jul-2022 08:21

    Paul,

    My answer is none of the above. For software life cycle you should follow IEC 62304:2006+AMD1:2015 and EN 62304:2006/A1:2015, both of which lead to 14971 (ISO 14971:2019 and EN ISO 14971:2019/A11:2021).

    The process for hazard analysis is none of PHA, FMEA, HAZOP etc. The process, well described in 14971, doesn't have a commonly recognized name, so I call it Hazard Analysis. This parallels the name Failure Modes and Effects Analysis which analyzes single point failures. In medical device risk management, analyze hazards which can occur in normal or fault conditions involving a sequence of events, not a single point failure.



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    Dan O'Leary CQA, CQE
    Swanzey NH
    United States
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  • 5.  RE: Hazard Analysis for SaMD

    Posted 08-Jul-2022 04:40
    Dear Paul et al.

    I want to emphasise two sides to this story: the perspective provided in ISO 14971 and the approach outlined in IEC 62304. In short, they serve different purposes.

    As mentioned by @Edwin Bills, ISO 14971 is all about risk analysis and preferably something you start with early in your development work. A significant output from the risk analysis process is "hazardous situations", which happens to be an input to IEC 62304 (perhaps the single most important!).

    Software risk management per IEC 62304 asks you to identify what software items can contribute to hazardous situations. You should also determine what software causes may cause a software item to fail so that it can contribute to a hazardous situation. (IEC 62304 §7.1.1 and §7.1.2)

    Perhaps a simplification but ISO 14971 aims at product risk management - top-down. IEC 62304 asks how SW items can contribute to hazardous situations, so it can be considered a bottom-up approach.

    So what tools to use?
    For the SW risk analysis, FTA might be helpful. Hazardous situations can be placed on top. On the second level, software items can be identified, and at the bottom, you can identify software causes. (You can of course flip it if that makes more sense to you.)
    For risk analysis per ISO 14971, I find a tabular approach called "Hazard Trace Matrix" (HTM) straightforward and useful.

    If you want to learn more about working with ISO 14971 and using a hazard trace matrix, there is an excellent introductory course on this topic on YouTube: Risk management for medical devices and ISO 14971 - Online introductory course

    Hope you find it helpful!




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    Christian Kaestner
    Sweden
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