Association between 6-month outcomes and the systemic inflammatory response index, HMGB1, and IL-33 levels in patients with traumatic spinal cord injury: A retrospective cohort study

BACKGROUND: Spinal cord injury (SCI) is a devastating condition characterized by variability in injury mechanisms and neurologic recovery. Complex reactive cellular responses and the release of cytokines, which may be clinical biomarkers and therapeutic targets, occur immediately after SCI. In the present study, we aimed to determine alterations in the systemic inflammatory response index (SIRI) and the levels of HMGB1 and IL-33 in patients with traumatic SCI (tSCI) and investigate their associations with 1-year outcomes. MATERIALS AND METHODS: Forty patients were admitted to the intensive care unit after tSCI due to traffic accidents, falls, or sports-related injuries. Blood samples were collected within 24 h and 7 days after SCI. Twenty age- and sex-matched healthy volunteers were included as controls. Neurologic and functional status were evaluated via the American Spinal Injury Association Impairment Scale (AIS) grade at admission, at discharge, and 6 months after SCI. Serum levels of HMGB1, IL-33, IL-1β, and TNF-α were determined via ELISA. The discriminative ability of those indicators in predicting the AIS grade at 6 months was determined by receiver operating characteristic (ROC) analysis. RESULTS: Compared with those of the controls, the HMGB1, IL-33, IL-1β, and TNF-α levels, as well as the SIRI and neutrophil-lymphocyte ratio (NLR), were significantly elevated within 24 h and 7 days after SCI. These indicators peaked within 24 h and then decreased at 7 days post-SCI. Among the 40 patients with tSCI, 23 (57.5%) were categorized into the neurologically complete tSCI group (AIS A-B). SIRI, HMGB1, IL-33, and IL-1β levels and the NLR were greater in patients in the neurologically complete tSCI group and poor outcome group than in those in the neurologically incomplete tSCI group or good outcome group. ROC analysis revealed that the levels of the SIRI (AUC = 0.884) and IL-33 (AUC = 0.822) at 24 h and the levels of HMGB1 (AUC = 0.922) and IL-33 (AUC = 0.816) on day 7 demonstrated excellent predictive value for poor neurological outcomes (AIS A-C) at 6 months. CONCLUSION: Elevated levels of SIRI, HMGB1, and IL-33 are strongly associated with more severe initial injury and are significant predictors of poor 6-month neurological outcomes after tSCI.