As a physician I saw a patient that was injured by the neglegent conduct of another physician . The neglect was passive neglect to diagnose and treat. The patient now requires more intensive treatment with less likelihood of success
Do I have an obligation to tell the patient that his previous doctor erred or does my responsibility on go so far as to give proper care going forward?
If your intent is to help the patient get the best treatment, and avoid potentially negligent doctors, it would be proper to inform him of the negligence.