Thanks Ronen. Yes the clinical trial will be done in the US. Just to clarify that this is a drug clinical trial, the IVD/MD will just be a component of the trial and only acts as an accessory. The IVD/MD in question is a software package and I'm not sure how it will be classified in the FDA system. Currently in the EU for CE marking it is classed as low risk.
Please take the following with a pinch of salt as I'm not an expert on drug trials.
Unless there's a provision in drug clinical trials regulations that deals with accessories to the main subject of the trial (the drug), I still think that regardless of the settings the IVDMD will need to be cleared in its own right for use in a clinical trial, ie have an IDE. IDE stands for Investigational Device Exemption - it is an exemption from the "normal" requirements that would apply to the device if it was to otherwise be clinically used. In other words you will be putting into use a device that doesn't necessarily comply with the "normal" applicable regulations, so in order to legally do so you need an official exemption - the IDE.
Regarding classification, you could either look for an equivalent / similar software that's already cleared and look up its classification; or you could browse the classifications database and try to spot a classification that reads well on your software (then you could verify adequacy by comparison with other cleared devices under the same classification).
Classification in the EU is unfortunately mostly irrelevant.
Cheers,
Ronen.