Apparently there is no legal obligation for the doctors to inform the police as and when changes happen. Not all do. So while that continues there is no option but to recheck at regular intervals.The whole idea of the marker on your medical record was that the police would already have been notified about any relevant changes to your health or medical conditions, thus would not need to do the proforma every 5 years.
The fact they seem to have made participation in even that turns the whole thing into a farce.
Blame the doctors surgeries for this (and other very poor service issues).