Your problem is that your data IS going to be extracted (eventually), even if you opted-out, because that is what the system is intended for. Your opt-out just (theoretically) defines the end users of the data; some get it, others do not.
In the case of your summary care records, you have no say at all. They are only for use by "healthcare professionals" (mission-creep rules apply). http://systems.hscic.gov.uk/scr
Your care.data records are the ones being discussed. http://www.nhs.uk/NHSEngland/thenhs/records/healthrecords/Pages/care-data.aspx
As always, what you start with is not what you end with. I would be extremely surprised if system resilience had not included considerable user resistance in the design phases, and then designed out the resistance. Care.Data will roll-out, eventually, with end dissemination decided by the design team and not by the data subject. Or maybe you thunk that the DPA exemption for HSCIC was for another reason?