Association of hemoglobin variation and hospital mortality in patients with traumatic brain injury at high altitude

Backgroud Traumatic brain injury (TBI) ranks among the leading causes of death worldwide. However, the association between hemoglobin variation (ΔHb) and hospital mortality in TBI patients at high altitude remains uninvestigated. Method This retrospective cohort study was conducted from January 2020 to March 2025 in the Tibetan Plateau region, enrolling 191 patients who resided at an average altitude of 3,000 m. ΔHb (peak Hb-nadir Hb) during the hospitalization, related covariates and hospital mortality were collected. Backward stepwise multivariable logistic regression was used to select key variables. The non-linear relationship between ΔHb and mortality was investigated using the multivariable fractional polynomial (MFP) method. The threshold effects of ΔHb were explored through two-piecewise logistic regression models. Results Logistic regression showed that ΔHb was independently and significantly associated with hospital mortality (OR = 1.08, 95% CI: 1.02–1.15, P = 0.005) after adjustment for nadir Hb, diffuse axonal injury and GCS (Glasgow coma scale) score. A cubic non-linear relationship between ΔHb and hospital mortality was revealed ( P for non-linearity = 0.010), with an inflection point at 19.8 g/L. Additionally, an interaction effect between ΔHb and GCS score was found ( P = 0.035). Conclusions In the clinical management of high-altitude TBI patients, our findings suggest that those with a ΔHb > 20 g/L, and a substantially elevated ΔHb and a low GCS score have an increased risk of mortality. A study investigating interventional strategies aimed at reducing ΔHb in TBI patients is warranted.