The Impact of Perioperative Renal Function on Outcomes in Multi-Level Spinal Fusion for Adult Degenerative Scoliosis

Introduction: Adult degenerative scoliosis (ADS) is a process that can cause symptomatic spinal misalignment often treated with multi-level spinal fusion. Preoperative renal function has been shown to affect ADS surgical outcomes. This study seeks to investigate the impact of preoperative renal function on postoperative outcomes following spinal fusion for ADS.

Methods: Patients who underwent long-segment thoracolumbar fusion (≥4 levels) for spinal deformity at our institution from 2016-2020 were included. Lab values two weeks before surgery were included in the analysis as well as creatinine clearance (CrCl). Linear regression model assessed the relationships between preoperative renal function and postoperative outcomes. Multivariate regression included race, sex, age, height, weight, and comorbidities.

Results: 235 consecutive patients including 155 females with an average age of 69.6±8.2 who underwent spinal fusion were included in the analysis. The presence of chronic kidney disease (n=17) predicted a high preoperative blood urea nitrogen (BUN) (p < 0.005) and CrCl (p=0.013) but not creatinine (p=0.76). Patients with lower creatinine were more likely to be given albumin intraoperatively (OR: 0.0014, 95%CI: 0.0002-0.0027, p=0.028). Preoperative BUN was not predictive of any change in outcomes. High preoperative creatinine predicted need for earlier revision surgery (OR: 0.035, 95%CI: 0.006-0.064, p=0.025). High preoperative CrCl predicted earlier initiation of walking postoperatively (OR: 9.52E-05, 95%CI: (2.64E-5)-0.00016, p=0.007) and was protective against the need for blood products postoperatively (OR: 0.999, 95%CI: 0.999-0.999, p=0.023).

Conclusion : Better preoperative renal function, as reflected by lower creatinine and higher CrCl, were predictive of earlier initiation of walking and protected against needing postoperative blood products. CrCl was found to be a better predictor of outcomes than BUN or creatinine. These findings suggest that surgeons should consider patient renal function beyond readily available laboratory findings and aim to aggressively optimize renal function before surgery.