Derivation and validation of a preoperative prediction rule for delirium after cardiac surgery.
BACKGROUND
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.


RESULTS
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 < or =23 received 2 points, and Mini Mental State Examination score of 24 to 27 received 1 point; Geriatric Depression Scale >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).


CONCLUSIONS
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.
Rudolph
James L
JL
VA Boston Healthcare System, Geriatric Research, Education, and Clinical Center, 150 S Huntington Ave, Boston, MA 02130, USA. jrudolph@partners.org
Jones
Richard N
RN
Levkoff
Sue E
SE
Rockett
Christopher
C
Inouye
Sharon K
SK
Sellke
Frank W
FW
Khuri
Shukri F
SF
Lipsitz
Lewis A
LA
Ramlawi
Basel
B
Levitsky
Sidney
S
Marcantonio
Edward R
ER
D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D015331:Cohort Studies; D003693:Delirium / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D012307:Risk Factors