Final answer:
The primary reason for requiring written consent is to preserve confidentiality and respect subjects' rights to privacy and dignity.
Step-by-step explanation:
The primary reason for requiring written consent from a client to share information from their medical record with another facility is to preserve confidentiality and respect subjects' rights to privacy and dignity. Written consent ensures that the client gives permission for their medical information to be shared and also guarantees that any data collected will remain completely confidential. This requirement is in line with legal considerations, such as the Health Insurance Portability and Accountability Act (HIPAA), which sets standards for patient information protection and establishes strict confidentiality for patient records.