Abstract 888: Use of Cognitive and Global Functioning Assessment to Predict Delirium in Cardiovascular Surgery Patients
Background: Delirium following cardiac surgery is common (25– 47%) and much attention has been devoted to improving its recognition and treatment. Despite the potential for pre-op assessments of psychological function to guide risk factor reduction, assessments of preoperative psychological and cognitive function are used inconsistently and their prognostic value understudied.
Method: Prospective cohort design of 134 consecutive patients referred for assessment of cognitive impairment and psychiatric disorders prior to cardiac surgery at a tertiary care center from 01/08 to 03/08 and who received at least one follow-up visit. Assessments conducted by a psychiatrist included a focused history, the Mini-Mental State Exam (MMSE) and Global Assessment of Functioning (GAF). All patients were followed by the same psychiatrist through their postoperative stay to assess for DSM-IV defined delirium. Group differences for categorical variables were assessed using chi-square and multivariate logistic regression for predictors of delirium.
Results: Delirium occurred in 38 (28.4%) of subjects. Significant bivariate predictors of delirium included male gender (OR 2.7, p =.02) and MMSE scores under 25 (OR 7.9, p<.001). Patients with GAF scores below 70 were at approximately 7-fold increased risk. While older age (over 70) showed a trend toward significance (OR 2.0, p=.06), neither surgery type nor variables related to psychiatric history were significant bivariate predictors. Multivariate modeling confirmed gender, MMSE, and GAF scores (but not age) as independent, simultaneous predictors of delirium; after control for these factors, heavy alcohol consumption was associated with 3-fold increase in delirium risk.
Conclusions: Simple, validated measures of preadmission cognitive and general psychological functioning were strong predictors of preoperative delirium in a selected group of cardiac surgery patients identified as high risk at the time of referral; age and type of surgical procedure were not. Preoperative screening merits routine inclusion in protocols aimed at prevention and early identification of delirium, and deserves further exploration with larger samples and more comprehensive designs aimed at minimizing negative outcomes.