Regulatory Open Forum

 View Only
  • 1.  Statistical Sampling Plans

    Posted 04-May-2015 16:19
    I am looking for information on Statistical Sampling Plans for design validation testing (simulated or actual use) of Class I/Class II medical devices.

    Thank you!

    -------------------------------------------
    Kate Chase
    Beekley Corporation
    Bristol CT
    United States
    -------------------------------------------


  • 2.  RE: Statistical Sampling Plans

    Posted 05-May-2015 11:11
    Kate,

    Two good references:

    The draft Guidance for Industry, Applying Human Factors and Usability Engineering to Optimize Medical Device Design, Appendix B - Considerations for Determining Sample Sizes for Human Factors Validation Testing: June 2011

    ANSI/AAMI HE75:2009 Human Factors Engineering Design of Medical Devices: Annex A (Informative) 

    Please note as you consider these documents, these may not apply to the majority Class I as they are exempt from Design Controls. 

    Good luck,

    Dar

    -------------------------------------------
    Darlene Rosario RAC
    Principal Consultant RA, Quality and Compliance
    Velocity Consulting
    Ventura CA
    United States
    -------------------------------------------




  • 3.  RE:Statistical Sampling Plans

    Posted 06-May-2015 07:09
    Hi

    It is not always straightforward. The validation sampling plans should be endpoint driven to meet tolerance or acceptability targets. One needs to consider CVs if applicable. Sometimes a military sampling strategy (square root of N+1) can apply for routine production.

    -------------------------------------------
    Philip Lavin PhD, FASA, FRAPS
    Principal
    Lavin Consulting LLC
    Framingham MA
    United States
    -------------------------------------------





  • 4.  RE: Statistical Sampling Plans

    Posted 06-May-2015 15:57
    Interesting question, Kate.  I had a discussion with some members of our local RAPS chapter on a similar subject. 

    It has always been my understanding that one does not validate a design on human subjects.  Preference testing by physicians for handling, yes, but never with patient involvement.  We always used cadaver labs or other simulations for design validation.  We also did intense post-market surveillance for the first 6 months.

    What devices are you validating?  Maybe that and the nature of the validation may qualify my concerns.

    Does anyone else have information on this?

    -------------------------------------------
    John Minier RAC
    Small Bone Innovations, Inc
    Highland Mills NY
    United States
    -------------------------------------------




  • 5.  RE: Statistical Sampling Plans

    Posted 07-May-2015 11:10
    It has always been my understanding that most of the medical device industry does not want to validate a design on human subjects, which is to say that most of the industry does not want to have to conduct clinical trials.

    Over the years, I've seen FDA and other regulators make slow headway on this issue in the face of aggressive industry resistance. Nonetheless, the foundation for validating a design in human subjects was laid quite some time ago (all caps mine):

    Design validation shall ensure that devices conform to defined user needs and intended uses and shall include testing of production units under ACTUAL or simulated use conditions.
    --FDA's Design Control Guidance For Medical Device Manufacturers, March 11, 1997 

    The same guidance also notes that ""Many medical devices do not require clinical trials."  I think this would be more accurately stated as "FDA does not require clinical trials for many medical devices."

    The guidance further states, "However, all devices require clinical evaluation and should be tested in the ACTUAL or simulated use environment as a part of validation."  The ongoing question is whether you can really simulate use by a human.  Many (but definitely not all) engineers think you can; most (perhaps even all) clinical professionals who have dealt with live patients on a day-to-day basis would beg to differ.

    The engineers I've encountered who side with the clinical professionals are most commonly those who have designed Class III devices or who are biomedical engineers.  The latter is of interest, because I tend to think the biomedical engineers are also most likely to be experts in simulated use.

    One thing I personally think is certain...where a pivotal trial is conducted, its purpose IS design validation.  I expect there those here who will disagree with me on this, and I hope they will share their perspectives on the matter here.  However, if this is accepted as a certainty, the fact that pivotal trials are conducted on a regular basis would be confirmation that industry does, in fact, validate design in human subjects. I think many (but definitely not all) feasibility studies are also conducted to validate some aspects of a design.



    -------------------------------------------
    Julie Omohundro, MBA, RAC
    Class Three, LLC
    Durham NC
    United States
    -------------------------------------------