Please assess the completion status of the following clinical trial:

Trial Title: Preoperative Vitamin B12 and Folic Acid on POCD in Elderly Non-cardiac Surgical Patients

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: DOUBLE
- Phase: None
- Number of Arms: 3.0

Eligibility Criteria:
Inclusion Criteria:~* 1. Age equals or over 65~* 2. Scheduled for spinal or joint replacement surgery under general anesthesia，estimated surgery time over 2h.~* 3. Signed written informed consent obtained~* 4. Non-surgical Controls are age and sex - matched community elderly residents.~Exclusion Criteria:~* 1. Disease of the central nervous system that impairs cognitive function, including all kinds of dementia, and depression~* 2. MMSE score \< 24~* 3. Received education for less than 5 years~* 4. Currently taking sedative or antidepressant drugs~* 5. Has taken vitamin B12, folic acid or their derivatives (methycobalamin, cobalamin, tetrahydrofolic acid, etc.) within 6 months.~* 6. Has accepted cardiac or neurological surgery within one year.~* 7. Was admitted for other clinical trials within 3 month~* 8. Patients that regularly taking drugs that affect vitamin B absorption, including colchicine, neomycin, salicylate.~* 9. Has severe visual or auditory problems~* 10. Alcohol or drug dependent (alcohol dependent: drank more than 100 mL of Chinese liqueur with alcohol concentration over 40% everyday for the past 3 months).~* 11. Patients that are already admitted for this study can not be admitted the second time, no matter the cause of surgery

- Gender: ALL
- Minimum Age: 65 Years
- Maximum Age: None
- Healthy Volunteers: f

Study Arms:
- VB12+FA (Type: EXPERIMENTAL): Patients will receive oral supplementation of 0.5mg methylcobalamin, 3/day and 5 mg folic acid, 1/day for 7 days before non-cardiac surgery.
- Placebo (Type: PLACEBO_COMPARATOR): Patients with receive oral tablets of placebo for folic acid 1/d and placebo for methylcobalamin 3/d, which look exactly like the interventional drugs as oral supplementation for 7 days before non-cardiac surgery.
- Non-surgical controls (Type: OTHER): Age and sex-matched community elderly people are included for two sessions of NPB test evaluation for calculation of POCD incidence as normal control to in Z value calculation of POCd incidence to rule out learning effect.

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