Risk Factors for Delirium After Spinal Surgery: A Meta-Analysis

OBJECTIVE: Postoperative delirium can occur following various types of surgeries. The specific risk factors for delirium following spinal surgery have not been systematically evaluated. The aim of this study is to conduct a meta-analysis of the risk factors for delirium after spinal surgery. METHODS: PubMed, EMBASE, the Cochrane Library, and Science Citation Index were searched from inception to October 2014 for original research studies. Relevant studies on patients with delirium following spinal surgery were included if they identified at least 1 risk factor as being associated with delirium. The Newcastle-Ottawa Scale (NOS) was used for the study quality assessment, and the pooled odds ratios (ORs) were used for determining the risk factors. RESULTS: Six articles met the inclusion criteria. Twenty-four risk factors in the multivariate analyses and 22 factors in the univariate analyses were significantly associated with delirium following spinal surgery. In the pooled analyses, age >65 years (OR: 6.13; 95% confidence interval [CI]: 5.75, 6.54); female sex (OR: 1.21; 95% CI: 1.15, 1.28); number of medications (mean difference [MD]: 1.36; 95% CI: 0.73, 2.00); low preoperative hematocrit (MD: L1.67; 95% CI: L2.97, -0.38) and albumin (MD: -0.33; 95% CI: -0.53, -0.13); duration of surgery (MD: 35.79; 95% CI: 1.42, 70.16); intraoperative blood loss (MD: 124.44; 95% CI: 100.03, 148.85); low postoperative hematocrit (MD: L2.58; 95% CI: L3.70, L1.46), hemoglobin (MD: L1.10; 95% CI: L1.86, -0.35), and sodium (MD: L2.97; 95% CI: L5.42, -0.51); and postoperative fever (OR: 4.52; 95% CI: 2.94, 6.95) were significantly associated with delirium. CONCLUSIONS: Several risk factors were consistently associated with delirium following spinal surgery, which can be used to identify high-risk patients. Recognizing these patients is important for physicians to develop preventive strategies to reduce postoperative delirium and its negative consequences.