Impact of Immunosuppression Type on 30-Day Postoperative Outcomes Following Anterior Cervical Discectomy and Fusion: A Retrospective National Cohort Study of 66,162 Patients

Abstract

Study Design Retrospective Cohort Study. Objectives Perioperative immunosuppression management in spine surgery lacks robust evidence. Most NSQIP-based ACDF models utilize a binary steroid variable, failing to distinguish corticosteroids from biologics or synthetic DMARDs. This study uses the granular NSQIP immunosuppression category and propensity score matching (PSM) to validate these risks. Methods Primary ACDF patients were identified in ACS NSQIP (2015–2021; N=66,162). The primary exposure was preoperative corticosteroid use; a secondary analysis utilized the 2021 granular immunosuppression variable (n=9,761). The primary outcome was a 30-day composite adverse event (complication, readmission, reoperation, or mortality). Analysis included multivariable logistic regression and 1:3 PSM. Results Preoperative corticosteroid exposure (3.8%) independently predicted the composite outcome (aOR 1.35, 95% CI 1.16–1.56), readmission (aOR 1.37), and medical complications (aOR 1.38; all p<0.001). Risk was driven by sepsis (aOR 2.00), UTI (aOR 1.67), and pneumonia (aOR 1.44), while wound complications and reoperation rates were not elevated. PSM confirmed these findings and revealed a mortality signal (aOR 2.10, p=0.03). Among 2021 patients, corticosteroids significantly increased risk (aOR 1.95; p=0.004), whereas biologic and synthetic DMARDs showed no significant elevation, though these subgroups were severely underpowered (<10%). Conclusions Corticosteroid use is independently associated with increased 30-day infectious complications, readmission, and mortality following ACDF. Null findings for biologics and synthetic DMARDs reflect inadequate power rather than proven safety. Perioperative risk modification should prioritize minimizing corticosteroid burden over the cessation of biologic therapies.