Final answer:
The claim regarding the inability to sign EHR messages is false; EHR systems allow for electronic signatures to confirm the sender's identity and message integrity.
Step-by-step explanation:
The statement that one disadvantage of using EHR messages is that the person creating the message is unable to sign it is false. Electronic Health Records (EHRs) typically have features that allow healthcare providers to electronically sign their messages. This electronic signature verifies the identity of the message creator and the message's integrity, serving much like a handwritten signature in a traditional paper record. Additionally, EHR systems often include strict user authentication and access control mechanisms to ensure that messages and records are securely signed and maintained.