158. Plasma cytokine biomarkers are predictive of chronic postsurgical pain following complex spine surgery

Abstract

<h3>BACKGROUND CONTEXT</h3> Spine surgery in older adults is beneficial and often results in decreased pain. However, in a subset of older adults, surgical outcomes are less desirable, with up to 20% experiencing persistent postsurgical pain (>3 months). The physiological mechanisms underlying persistent postsurgical pain remain unclear. An emerging hypothesis focuses on the immune system's interplay with the nervous system wherein immune responses modulate the excitability of pain pathways, eventually driving chronic pain hypersensitivity. <h3>PURPOSE</h3> The aim of this study was to correlate immune activity with postoperative pain states by analyzing cytokine levels following complex spine surgery. <h3>STUDY DESIGN/SETTING</h3> Prospective, single-center cohort. <h3>PATIENT SAMPLE</h3> Fifteen patients undergoing complex spine surgery for adult spinal deformity were enrolled in this study. <h3>OUTCOME MEASURES</h3> Pearson correlation and linear regression models were used to assess the association between cytokine profile and patient reported pain outcomes at 3 months (VAS Back and PROMIS pain scores). <h3>METHODS</h3> Whole blood samples were collected at three timepoints: preoperatively, postoperative day 0 (POD0), then at postoperative day 3 (POD3). Plasma was isolated using Ficoll density centrifugation. Plasma IL-4, IL-6, IL-8, IL-10, IL-22, TNF-α; were measured using a Quanterix Multi-Plex cytokine assay. <h3>RESULTS</h3> Compared to baseline there was a 2.7-fold and 5-fold increase in IL-6 at POD0 and POD3, respectively (p<0.01). There were no statistically significant differences in other cytokines expression levels following surgery. On linear regression analysis, increase in IL-6 levels from baseline to POD3 were correlated with increased opioid utilization on POD3. At 3-months, cytokine expression levels in IL-6, IL-10 and TNF-α at POD0 were inversely correlated with 3-month VAS Back Pain scores and PROMIS scores. <h3>CONCLUSIONS</h3> Following spine surgery, patients exhibited a robust increase in IL-6, a pro-inflammatory cytokine. Patients with higher pain scores at 3-months postoperatively had a more blunted immune response immediately after surgery (POD0). Further biochemical and ex-vivo studies are needed to fully characterize immune response to surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.