Association between preoperative neutrophil-lymphocyte ratio, uric acid, and postoperative delirium in elderly patients undergoing degenerative spine surgery

Purpose: There are few reports regarding the association between the neutrophil-lymphocyte ratio (NLR), uric acid, and the development of postoperative delirium (POD) in patients who are undergoing spine surgeries. We investigated the associations between the NLR, uric acid as a natural antioxidant, and POD in elderly patients undergoing degenerative spine surgery.

Patients and methods: This was a single-center, observational, and retrospective study conducted in Japan. We enrolled 410 patients who underwent degenerative spine surgery. POD was diagnosed after the surgeries by psychiatrists, based on the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V). We performed a multivariable logistic regression analysis to clarify whether the NLR and uric acid values were associated with the development of POD in the patients.

Results: 129 of the 410 patients were excluded from the analysis. Of the 281 patients (137 females, 144 males), 32 patients (11.4%) were diagnosed with POD. The multivariable logistic regression analysis revealed that the preoperative uric acid level (adjusted odds ratio [aOR]: 0.67, 95% confidence interval [CI]: 0.49-0.90, p = 0.008) and age (aOR: 1.09, 95% CI: 1.02-1.16, p = 0.008) were significantly associated with POD. The preoperative NLR (aOR: 0.82, 95% CI: 0.60-1.13, p = 0.227) and antihyperuricemic medication (aOR: 0.97, 95% CI: 0.24-3.82, p = 0.959) were not significantly associated with POD.

Conclusion: Our results demonstrated that in elderly patients undergoing degenerative spine surgery, the preoperative NLR was not significantly associated with POD, but a lower preoperative uric acid value was an independent risk factor for developing POD. Uric acid could have a neuroprotective impact on POD in patients with degenerative spine diseases.