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  1. #1
    Forum Member
    Join Date
    Dec 2011

    Fasting before Consent

    Is fasting classified as a study procedure - therefore should a subject give consent before beginning a fast, for example for a screening blood test?

    My understanding over the last few years has been that the requirement for no trial procedure to take place before consent extends to asking potential subjects to fast for screening blood tests. But I have just come across a REC approved protocol which appears to permit this.

    I am wondering about the impact on insurance and indemnity, if a subject were to have e.g. a dizzy spell due to fasting. Also I am slightly concerned that patients are coming in fasted, and then have to sign a consent form before they have their bloods taken and before they can have something to eat, and therefore their opportunity to ask questions might be influenced by a wish not to prolong proceedings.

  2. #2
    Forum Member
    Join Date
    Nov 2012
    The patients should be given the Patient information sheet and consent form to take home and carefully read it and think about it. They are given at least 24 hours to think and discuss with their family members about joining the trial. The required fasting for screening bloods should be clearly mentioned in the PIS so that the patients are aware and prepared for this when they come in for their screening visit.

    The patients should be encouraged to ask and clarify all their questions. Usually it helps if they have an early morning appointment so that they don't have to prolong their fasting unnecessarily.

    I hope this helps?

  3. #3
    Forum Member
    Join Date
    Nov 2011
    Interesting question as it does not just apply to fasting, another example would be when subjects might be asked to refrain from sexual activity for 48 hours prior to a protocol required sample collection; or other pre-requisites.

    The need for written informed consent prior to conducting any protocol required activities with subjects is paramount. However, it may acceptable (as suggested in the MHRA GCP Guide) to provide general information to a potential subject prior to screening which might include the general requirements of the study, including suitable testing conditions. The Ethics Committee must explicitly approve the offer to subjects to provide fasting samples upon screening. The Ethics Committee should be able to pass an opinion on this. It would be inappropriate to do this with vulnerable groups such as the elderly. If subjects do take up the offer of arriving fasted, then they should be warned about possible consequences (dizziness, etc). I do agree that subjects might feel obliged to participate now that they have gone to the trouble of fasting. If in any doubt, the subject should feel free to take longer to think about the trial and come back for another visit. When safeguards are in place and the risk is low to the subject, then it is the subject’s free choice to decide whether or not to arrive for the screening visit having met those conditions and they should be informed that failure to arrive in that condition will not preclude them from being screened. No pressure or undue influence should be put on the potential subjects to conform to the screening test requirements. Protocols should not be written that would exclude subjects from screening simply because the testing conditions were not met at the initial visit. Processes should permit the required tests to be done at a later date, perhaps within a window defined as the screening visit, or at a subsequent visit. At no time should it be suggested to a subject to begin a wash-out period, change a medication, or do anything that could affect his or her medical condition, safety or well being, prior to having the full study explained and obtaining their written informed consent. It must be remembered that potential subjects must have “ample time and opportunity” (ICH GCP 4.8.7) to think about and discuss the study, before beginning any study related activities. For low risk studies the MHRA has suggested that consent by mail might be possible. In a similar way subject information and consent forms could be sent to subject in advance and the study discussed with them over the phone. They would then know about the fasting conditions and would be able (if their questions were fully answered) to consent at the begging of their visit, therefore not delaying the blood test. In the case of multi-national trials, it is not known how other regulatory authorities may view this process. It would be best to check with them.

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