You have a choice to make
Please see below message from NHS England:
"Confidential information from your medical records can be used by the NHS to improve the services offered so we can provide the best possible care for everyone. This information along with your postcode and NHS number but not your name, are sent to a secure system where it can be linked with other health information. This allows those planning NHS services or carrying out medical research to use information from different parts of the NHS in a way which does not identify you"
You have a choice. If you are happy for your information to be used in this way you do not have to do anything. More information can be found here www.nhs.uk/caredata. If you have any concerns regarding this matter or wish to prevent this from happening please email firstname.lastname@example.org