A patient who was transported by EMS for a laceration on her arm is suing the service and the hospital because her laceration became infected, resulting in loss of the extremity. However, it becomes known that the patient was appropriately treated by EMS and the emergency department, but failed to seek follow-up medical care at a health clinic and did not take the antibiotics that were prescribed to her. Which element would most likely be used by the medical community as a defense in this case?