Sex-based differences in early neurological recovery after traumatic spinal cord injury

BACKGROUND Traumatic spinal cord injury (SCI) causes profound and lasting disability. Early neurological recovery, as captured by conversion in American Spinal Injury Association Impairment Scale (AIS) grade, is a key prognostic indicator. While preclinical studies suggest sex-based neuroprotective mechanisms, the impact of biological sex on AIS conversion remains unclear. The objective of this study was to determine whether female sex is independently associated with increased odds of AIS conversion during hospitalization for SCI. METHODS We conducted a retrospective cohort study using data from the Spinal Cord Injury Model Systems database (2012–2021). Patients with non-missing sex and AIS discharge data were included. The primary exposure was reported sex at admission, and the primary outcome was AIS conversion during hospitalization. Multivariable logistic regression models adjusted for demographic and clinical covariates, including age, mechanism of injury, multiple trauma, spinal surgery, and baseline AIS grade. Sensitivity analyses excluded patients with AIS grade A injuries and those ≥65 years of age. A propensity score-matched analysis was also performed. RESULTS Among 7,910 patients (median age, 40 years; interquartile range, 26–56 years), 20% were female. Association Impairment Scale conversion occurred in 31% of patients. Female sex was independently associated with higher odds of AIS conversion (odds ratio, 1.23; 95% confidence interval, 1.07–1.42; p = 0.004). This association remained significant across sensitivity analyses and after propensity score matching (odds ratio, 1.26; 95% confidence interval, 1.09–1.46; p = 0.002). CONCLUSION Female sex was independently associated with greater odds of early neurologic recovery after SCI, as measured by AIS conversion. These findings suggest biological or biomechanical differences may influence short-term SCI recovery and underscore the need for sex-informed approaches in SCI research and rehabilitation. LEVEL OF EVIDENCE Retrospective Cohort Study; Level III.