Please assess the completion status of the following clinical trial:

Trial Title: Intraoperative Dexmedetomidine and Long-term Outcomes in Elderly After Major Surgery

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE4
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Elderly patients (age ≥60 years);~* Scheduled to undergo elective major non-cardiac surgery with expected duration ≥2 hours under general anaesthesia.~Exclusion Criteria:~* Do not provide written informed consent;~* Previous history of schizophrenia, epilepsy or Parkinson's disease;~* Visual, hearing, language or other barriers which impede communication and preoperative delirium assessment;~* History of traumatic brain injury;~* Severe bradycardia (heart rate \<40 beats per minutes), sick sinus syndrome, or atrioventricular block of degree 2 or above without pacemaker;~* Severe hepatic dysfunction (Child-Pugh grade C);~* Renal failure (requirement of renal replacement therapy);~* Neurosurgery.

- Gender: ALL
- Minimum Age: 60 Years
- Maximum Age: None
- Healthy Volunteers: f

Study Arms:
- Intervention group (Type: EXPERIMENTAL): A loading dose of dexmedetomidine (0.6 μg/kg) was administered during a 10-minute period before anaesthesia induction, followed by a continuous infusion at a rate of 0.5 μg/kg/hr till 1 hour before the end of surgery.
- Control group (Type: PLACEBO_COMPARATOR): Volume-matched normal saline was administered in the same rate for the same duration as in the intervention group.

Based on this trial design, predict the completion outcome and termination type (if applicable).