Elevated C-reactive protein-to-albumin ratio with fever is a predictor of poor functional outcome in patients with mild traumatic brain injury

Introduction: The C-reactive protein -to-albumin ratio (CAR), a novel inflammation-based prognostic score, is useful in predicting clinical outcomes, including those in central nervous system diseases. However, no report has identified the relationship between CAR and long-term clinical outcomes in patients with mild traumatic brain injury (mTBI). We aimed to evaluate the relationship between CAR and long-term functional outcomes in patients with mTBI and analyze whether CAR is associated with the presence of fever. Methods: This was a retrospective observational study includes 387 adult patients with mTBI who were treated at a level-1 trauma center between 2017 and 2021. The main exposure variable was an elevated CAR, and the main outcomes were degrees of disability and quality of life measured using the modified Rankin Scale (mRS). A multivariable logistic regression analysis was performed to estimate the effect size of CAR on study outcomes. An interaction analysis was performed between CAR and fever on study outcomes. Results: Elevated CAR had no significant association with poor functional outcomes (aOR [95% CI]: 1.35 [0.39-4.69]) in patients with mTBI. In the interaction analysis, elevated CAR was not associated with increased poor functional outcomes in the absence of fever (1.08 [0.55-2.13]), but a significant increase in poor functional outcomes was observed when elevated CAR was accompanied by fever (1.32 [1.14-2.56)). Conclusions: Elevated CAR with fever increased the risk of poor functional recovery at 6 months after hospital discharge in patients with mTBI. Our study findings suggest the need for strategies for the prevention of long-term poor functional recovery in the presence of high CAR and fever in patients with mTBI.