I think that as long as you have documented your sincere attempt to contact them or to urge them to make an appointment or that you told them you will not refill meds without a follow up, you would have less (but perhaps not complete) culpability. I was involved in a case where a patient had a slightly elevated prolactin in the face of a normal MRI. No other reasons for the elevation could be found either. She was instructed to follow up every six months for repeat prolactins. She did not. We documented several times when we had called her and expressed concern than she had not had another level done. She still did not make an appointment. Two years later she has visual problems, sees her ophthalmologist, he gets another MRI and she clearly has a pituitary tumor. She suffered permanent complications from the neurosurgery and then filed a suit against me for failure to diagnose. It was dismissed because I had clearly warned her of the need for follow up.