Preexisting cognitive impairment, such as mild cognitive impairment, is common in many elderly patients who undergoing major surgeries. Accumulating evidence has demonstrated that preexisting cognitive impairment is associated with increased mortality, increased incidence of postoperative complications, decreased quality of life, and worse outcomes. However, few studies have evaluated the relationship between preexisting cognitive impairment and cognitive trajectories and clinical outcomes.

Preexisting cognitive impairment is common in many elderly patients who undergoing major surgeries. The number of surgical procedures in the elderly will increase dramatically as a result of the increased elderly population in the future. It has been suggested that preexisting cognitive impairment is associated with increased incidence of postoperative complications, decreased quality of life, and increased mortality. Preoperative risk assessment is becoming increasingly important because preoperative risk stratification allows the clinical team to forecast postoperative outcomes. Currently, the most common strategy to identify high-risk patients before surgery is assessment of single end-organ function. This tactic is most widely recognized by the American Heart Association's guideline for cardiac evaluation, but is also well described for pulmonary, hepatic, and renal organ systems. Little is known about the effects of pre-existing cognitive (or brain) function (perhaps the most vital human organ) on postoperative outcomes. Therefore, the present study evaluated whether patients with pre-operative cognitive impairment would have a more precipitous drop in cognitive function and worse outcome in geriatric surgical patients.

Inclusion Criteria:

- Inclusion criteria were persons 65 years and older undergoing an elective operation on the general, noncardiac thoracic, urologic, and vascular surgical services.

Exclusion Criteria:

- Patients with vision or hearing impairment who could not visualize pictures or hear instructions associated with the delirium assessments and patients who could not provide informed consent.

Patients were 65 years and older undergoing an elective operation on the general, noncardiac thoracic, urologic, and vascular surgical services.