Preoperative Prognostic Nutritional Index as a Useful Tool for Predicting Postoperative Delirium in Elderly Patients with Degenerative Lumbar Diseases.

PURPOSE: The high incidence of postoperative delirium (POD) among patients undergoing lumbar spine surgery presents a significant barrier to achieving enhanced postoperative recovery. Accordingly, a thorough understanding and precise identification of common risk factors for POD in this surgical context are crucial to mitigating its occurrence and facilitating improved recovery outcomes. This study is the first to assess the predictive value of the Prognostic Nutritional Index (PNI) for POD in elderly patients undergoing transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spine disease.

METHODS

We conducted a retrospective analysis of the outcomes of TLIF surgery in elderly patients with degenerative lumbar spine disease between 2020 and 2024. The diagnosis of POD was based on postoperative medical records during hospitalization, using the Confusion Assessment Method. The PNI was calculated based on preoperative serum albumin levels and total lymphocyte counts. Multivariate logistic regression analysis was performed to evaluate the relationship between preoperative PNI scores and the occurrence of POD. Finally, the optimal PNI cut-off point for predicting POD was determined using the receiver operating characteristic curve.

RESULTS

POD was observed in 61 of 370 patients, with PNI being significantly lower in the delirium group. The mean PNI values were 43.02±3.44 in the non-delirium group and 48.53±3.72 in the delirium group. Multivariate logistic regression analysis revealed that low PNI (OR: 0.743; 95% CI: 0.597-0.924; p = 0.008), low serum albumin levels (OR: 0.759; 95% CI: 0.584-0.987; p = 0.040), and advanced age (OR: 1.096; 95% CI: 1.030-1.166; p = 0.004) were independent predictors of POD following TLIF. The area under the curve (AUC) for PNI on the receiver operating characteristic curve was 0.864±0.025. The cutoff value for PNI, determined using the Youden index, was 45.825, with a sensitivity of 82.0% and a specificity of 74.4%.

CONCLUSION

The preoperative use of PNI holds promise as a valuable tool for assessing the risk of POD in elderly patients undergoing TLIF.