I worked in Walgreens headquarters for a while as a programmer. The lengths they went to in order to keep the Rx data confidential were extreme.
Maybe anticipated problems like this were one reason that HIPAA was ballyhooed (politicians who did not want to be outed on their medical histories) but nonetheless it’s law and someone would have to be insane to spill the beans.
Of course Rx data is supposed to be confidential. But the point is, that data exists and would be difficult to quietly delete. It’s not just a single server with emails under Hillary’s control. If the computers where the prescriptions are listed were broken into, it would look incredibly bad if she had covered up that information in her (sanitized) medical records. For all she knows, those computers have already been hacked just like her emails and the DNC’s emails were penetrated. Trump may already have the evidence in his hands and is ready to pounce, which is why he’s now demanding that she release her medical records.