Cognitive Trajectories after Postoperative Delirium

Delirium is a common and serious acute neuropsychiatric syndrome with core features of inattention and global cognitive dysfunction. The etiologies of delirium are diverse and multifactorial and often reflect the pathophysiological consequences of an acute medical illness, medical complication or drug intoxication. Delirium can have a widely variable presentation, and is often missed and underdiagnosed as a result. At present, the diagnosis of delirium is clinically based and depends on the presence or absence of certain features. Management strategies for delirium are focused on prevention and symptom management. This article reviews current clinical practice in delirium in elderly individuals, including the diagnosis, treatment, outcomes and economic impact of this syndrome. Areas of future research are also discussed.

Delirium is a common outcome after cardiac surgery. Delirium prediction rules identify patients at risk for delirium who may benefit from targeted prevention strategies, early identification, and treatment of underlying causes. The purpose of the present prospective study was to develop a prediction rule for delirium in a cardiac surgery cohort and to validate it in an independent cohort. Prospectively, cardiac surgery patients > or =60 years of age were enrolled in a derivation sample (n=122) and then a validation sample (n=109). Beginning on the second postoperative day, patients underwent a standardized daily delirium assessment, and delirium was diagnosed according to the confusion assessment method. Delirium occurred in 63 (52%) of the derivation cohort patients. Multivariable analysis identified 4 variables independently associated with delirium: prior stroke or transient ischemic attack, Mini Mental State Examination score, abnormal serum albumin, and the Geriatric Depression Scale. Points were assigned to each variable: Mini Mental State Examination 4, prior stroke/transient ischemic attack, and abnormal albumin received 1 point each. In the derivation sample, the cumulative incidence of delirium for point levels of 0, 1, 2, and > or =3 was 19%, 47%, 63%, and 86%, respectively (C statistic, 0.74). The corresponding incidence of delirium in the validation sample was 18%, 43%, 60%, and 87%, respectively (C statistic, 0.75). Delirium occurs frequently after cardiac surgery. Using 4 preoperative characteristics, clinicians can determine cardiac surgery patients' risk for delirium. Patients at higher delirium risk could be candidates for close postoperative monitoring and interventions to prevent delirium.

To develop and validate a clinical prediction rule for postoperative delirium using data available to clinicians preoperatively. Prospective cohort study. General surgery, orthopedic surgery, and gynecology services at Brigham and Women's Hospital, Boston, Mass. Consenting patients older than 50 years admitted for major elective noncardiac surgery between November 1, 1990, and March 15, 1992 (N = 1341). All patients underwent preoperative evaluations, including a medical history, physical examination, laboratory tests, and assessments of physical and cognitive function using the Specific Activity Scale and the Telephone Interview for Cognitive Status. Postoperative delirium was diagnosed using the Confusion Assessment Method or using data from the medical record and the hospital's nursing intensity index. Patients were followed up for the duration of hospitalization to determine major complication rates, length of stay, and discharge disposition. Postoperative delirium occurred in 117 (9%) of the 1341 patients studied. Independent correlates included age 70 years or older; self-reported alcohol abuse; poor cognitive status; poor functional status; markedly abnormal preoperative serum sodium, potassium, or glucose level; noncardiac thoracic surgery; and aortic aneurysm surgery. Using these seven preoperative factors, a simple predictive rule was developed. In an independent population, the rule stratified patients into groups with low (2%), medium (8%, 13%), and high (50%) rates of postoperative delirium. Patients who developed delirium had higher rates of major complications, longer lengths of stay, and higher rates of discharge to long-term care or rehabilitative facilities. Using data available preoperatively, clinicians can stratify patients into risk groups for the development of delirium. Since delirium is associated with a variety of adverse outcomes, patients with substantial risk for this complication could be candidates for interventions to reduce the incidence of postoperative delirium and potentially improve overall surgical outcomes.