A Simple Tool to Predict Development of Delirium After Elective Surgery

Abstract

Objectives: To identify a quick clinical tool to assess the risk of delirium after elective surgery.

Design: Prospective observational study.

Setting: Preoperative assessment clinic at the Veterans Affairs Portland Health Care System.

Participants: Community-living veterans aged 65 and older scheduled for elective surgery requiring general or major anesthesia.

Measurements: Confusion Assessment Method (CAM) or Family Confusion Assessment Method (FAM-CAM). Data on education, medications, substance use, Patient Health Questionnaire (PHQ-9), Study of Osteoporotic Fractures Frailty, Mini-Cog, and Charlson-Deyo score were collected preoperatively.

Results: Of 114 veterans who agreed to participate, 76 completed the final delirium assessment. Ten of the 76 (13%) developed delirium in the 72 hours after surgery as assessed using the CAM or FAM-CAM. In bivariate analysis, factors that increased the odds of delirium at least three times were low education; poor PHQ-9, clock draw, word recall, Mini-Cog, and poor preoperative orientation scores; alcohol use; and higher comorbidities as measured using Charlson-Deyo index. Scoring the Mini-Cog from 0 to 5 had a higher predictive power (area under the receiving operating characteristic curve = 0.77) than other approaches to scoring the Mini-Cog. Other models did not significantly improve prediction of postoperative delirium risk and would be complicated to use in a clinical setting.

Conclusion: In this sample of veterans who had elective surgery with major anesthesia, Mini-Cog score predicted likelihood of postoperative delirium.

Keywords: delirium; elderly; postoperative; prediction.