Ability of clock drawing errors on Mini-Cog test to predict development of delirium after major urological cancer surgery.

Background: This study aimed to evaluate the impact of the clock drawing test (CDT) on postoperative delirium and compare the abilities of the mini-cognitive (Mini-Cog) test and the CDT for predicting postoperative delirium after major urological cancer surgery.

Materials and methods: In this single-center retrospective observational study, we collected the medical records of patients who underwent major urologic cancer surgery and preoperative cognitive screening based on the Mini-Cog test consisting of the CDT and the 3-word recall task at our department in 2020-2021 (n = 387). Univariate and multivariate logistic regression analyses were used to identify the clinical risk factors for postoperative delirium. We also compared the ability of the CDT alone and the Mini-Cog test consisting of the CDT and 3-word recall task to predict postoperative delirium.

Results: A total of 117 patients (30%) had abnormal CDT results. Postoperative delirium occurred in 29 patients (7%). On multivariate analysis, American Society of Anesthesiologists physical status ≥3 (odds ratio [OR], 5.0; p = 0.01), abnormal CDT (OR, 4.8; p < 0.001), preoperative benzodiazepine use (OR, 4.9; p < 0.001), and operative time ≥237 minutes (OR, 3.0; p = 0.01) were independent risk factors for postoperative delirium. The area under the curve for predicting postoperative delirium was 0.709 for CDT alone and 0.743 for the Mini-Cog test. No significant intergroup difference was observed (p = 0.43).

Conclusions: The CDT served as a formal but simple tool with adequate predictive power to identify the risk of postoperative delirium among patients undergoing major urological cancer surgery. Effective screening using the CDT might help provide optimal urological care for older patients.