To the extent (if any, though I'd be surprised if there were none) IE11 doesn’t support standards required effectively, if indirectly, via the HITECH guidance on secured PHI, IE11 use could have some some adverse consequences under HIPAA (and, as a SaaS operator with a BAA that would include the vendor, not just the customer), but not in and of itself noncompliance for use or support. Mostly just making it more likely that situations would become reportable breaches.
To the extent (if any, though I'd be surprised if there were none) IE11 doesn’t support standards required effectively, if indirectly, via the HITECH guidance on secured PHI, IE11 use could have some some adverse consequences under HIPAA (and, as a SaaS operator with a BAA that would include the vendor, not just the customer), but not in and of itself noncompliance for use or support. Mostly just making it more likely that situations would become reportable breaches.