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

Postoperative delirium is common in older patients after spinal surgery. Many reports investigating the risk factors for delirium after spinal surgery have been published recently.

A literature search was performed using the Cochrane Library, Web of Science, PubMed, Embase, and Springer databases from inception to February 2019. Relevant studies involving patients with delirium who underwent spinal surgery were included if the studies contained data about blood transfusion or other related factors, such as haemoglobin, haematocrit, and blood loss levels. The Newcastle-Ottawa Scale was used for the study-quality evaluation. The pooled odds ratios or (standard) mean differences of the individual risk factors were estimated using the Mantel-Haenszel or inverse-variance methods.

Fifteen observational studies met the inclusion criteria; the studies included a total of 583,290 patients (5431 patients with delirium and 577,859 patients without delirium). In addition to an advanced age, the results of the meta-analyses showed that living in an institution, diabetes, cerebral vascular diseases, pulmonary diseases, opioid use, length of surgery, intraoperative blood loss, blood transfusions, intraoperative infusion, preoperative albumin, postoperative albumin, preoperative haematocrit, postoperative haematocrit, preoperative haemoglobin, postoperative haemoglobin, preoperative sodium, postoperative sodium, Mini-Mental State Examination score, inability to ambulate, depression, number of medications, and treatment with multiple drugs (> three types) were significantly associated with delirium.

The above-mentioned risk factors can be used to identify high-risk patients, and the appropriate prophylaxis strategies should be implemented to prevent delirium after spinal surgery.