Patient data should be mutable man! What if the patient suffered a condition in the past that he doesn't suffer anymore? The data should be updated.
This is vital, not just in the treatment and curing of previous conditions, but in the instances of mis-diagnoses, false-positive test results, or something as simple as incorrect data entry.
What if you get incorrectly labelled with a disease like cancer or HIV for any of the reasons above? Your health insurance will go through the roof. Being able to scrub things from patient records is a good thing.