Patient anesthetised with Inhalation anesthetic agents.

Patient anesthetised with total total intravenous anesthesia.

The Mini-Mental Status Examination is a screening tool for dementia. The investigator asks the patient a series of questions to which the patient answers to his or her best ability.

Minium score of zero and a maximum score of 30. Lower value represents a worse outcome.

A score of less than 24 is considered abnormal.

The Geriatric Depression Scale (short form) is a screening tool for depression. It is a questionnaire composed of 15 questions. The investigator asks the patient 15 questions in which the patient answers "yes" or "no".

Each question weighs 1 point with a minimum score of zero and maximum score of 15.

The higher the score, the more likely depression is present. A score of 0 to 5 is normal. A score greater than 5 suggests depression.

The Confusion Assessment Method is a screening tool for delirium. It comprises of four parts: "(1) acute onset and fluctuating course", "(2) inattention", "(3) disorganized thinking", and "(4) altered level of consciousness".

"(1) Acute onset and fluctuating course" has two questions and the rest with one question each.

The investigator conducts the assessment with the patient answering "yes" or "no" to each question.

Delirium is diagnosed under these scenarios: yes to all four questions, yes to (1)+(2)+(3), yes to (1)+(2)+(4).

Barthel Index is an ordinal scale used to measure performance in ADL (activities of daily living).

It comprises of ten variables describing ADL. A minium of zero and a maximum and 100 is scored. Higher score reflects greater ability to function independently. 60 or less is classified as dependent. Scores of 0-20 indicate "total" dependency, 21-60 indicate "severe" dependency, 61-90 indicate "moderate" dependency, and 91-99 indicates "slight" dependency