Risk factors for postoperative delirium after colorectal surgery: a systematic review and meta-analysis

Postoperative delirium is common after any type of surgery and can lead to serious outcomes; thus, its prevention is important. Early assessment can help identify patients at higher risk of postoperative delirium. However, the risk factors for postoperative delirium in patients who underwent colorectal surgery are unclear. This meta-analysis aimed to identify the risk factors for postoperative delirium after colorectal cancer surgery.

We selected all articles related to postoperative delirium after colorectal surgery published up to March 2019. Studies using any method for diagnosing delirium were eligible. Ovid-Embase, Ovid-Medline, and the Cochrane library were searched. Two reviewers independently conducted quality assessment and data collection. The risk factors identified in the studies were recorded, and a meta-analysis was conducted.

Of the 1216 studies initially screened, 1197 were reviewed by two independent reviewers. Finally, 14 articles were identified to be relevant for this review. In total, 11 of the 14 studies reported the risk factors for postoperative delirium. The incidence of postoperative delirium ranged from 8% to 54%. A total of 19 risk factors were identified, and we classified them into two categories as patient-related and treatment-related risk factors.

Postoperative delirium is highly common in those undergoing colorectal surgery including cancer, with advanced old age, history of preoperative delirium and preoperative serum albumin level which are risk factors for POD. Larger multi-institutional randomized studies to address this issue are warranted in the future.