Blood urea nitrogen-to-albumin ratio predicts outcomes in cerebral venous sinus thrombosis

An observational study of 803 adults with cerebral venous sinus thrombosis found that a readily available admission blood test, the blood urea nitrogen-to-serum albumin ratio, was independently associated with a higher likelihood of poor functional outcome six months after hospitalization. When combined with age, coma at admission, intracerebral hemorrhage and thrombosis involving the straight sinus, the ratio formed a prognostic nomogram that achieved an area under the receiver operating characteristic curve of 0.900 in a derivation cohort and 0.893 in a validation cohort. Cerebral venous sinus thrombosis, or CVST, is an uncommon form of stroke in which thrombotic occlusion of cerebral veins or dural venous sinuses impedes blood leaving the brain.

The resulting rise in venous pressure can produce intracranial hypertension, cerebral edema, hemorrhage and venous infarction. Its presentation is highly variable, ranging from headache, nausea and visual disturbance to seizures, encephalopathy, focal neurological deficits and coma. Although neurovascular imaging is essential for identifying the location and extent of thrombosis, imaging alone does not describe the metabolic and physiological stress experienced by an individual patient.

The investigators analyzed data from the Henan CVST Registry at the First Affiliated Hospital of Zhengzhou University. They screened 1,108 patients treated between January 2011 and December 2025 and included 803 adults in the final analysis. Eligible patients had been admitted within 30 days of symptom onset, had available admission blood urea nitrogen and serum albumin measurements, and had follow-up data.

Patients younger than 18 years, those hospitalized more than 30 days after symptom onset and those missing laboratory or follow-up information were excluded. The study population was randomly divided into a derivation cohort of 562 patients and a validation cohort of 241. Blood samples were collected within 24 hours of hospitalization.

The blood urea nitrogen-to-serum albumin ratio, abbreviated BAR, was calculated by dividing blood urea nitrogen in milligrams per decilitre by serum albumin in grams per decilitre. Blood urea nitrogen is routinely measured and can vary with renal perfusion, intravascular volume and protein catabolism, while serum albumin is influenced by inflammation, vascular permeability, nutritional status and overall physiological reserve. Functional outcome was assessed six months after the index hospitalization by trained neurologists who were blinded to patients’ baseline BAR values and model results.

A modified Rankin Scale score of 3 to 6 was classified as a poor outcome, while scores of 0 to 2 indicated a good outcome. Only 88 of the 803 patients, or 11.0%, had a poor six-month outcome. Compared with patients who recovered with good functional status, those with poor outcomes were older, with mean ages of 45.1 and 37.4 years, respectively.

Coma at admission was reported in 68.2% of the poor-outcome group but 21.5% of the good-outcome group. Seizures and focal neurological deficits were also more frequent among patients with poor outcomes. On imaging, intracerebral hemorrhage occurred in 42.0% of the poor-outcome group compared with 15.2% of the good-outcome group, while straight sinus thrombosis was present in 42.0% and 17.5%, respectively.

These differences describe the characteristics of the analyzed groups and do not by themselves establish causes of the subsequent outcomes. The laboratory profile also separated the groups. Patients with poor outcomes had higher mean blood urea nitrogen levels, 16.3 versus 11.3 mg/dL, lower mean serum albumin concentrations, 3.7 versus 4.1 g/dL, and a higher mean BAR, 4.6 versus 2.9.

Multivariable logistic regression in the derivation cohort identified older age, coma, intracerebral hemorrhage, straight sinus thrombosis and higher BAR as independent associations with poor functional outcome. For every one-unit increase in BAR, the adjusted odds ratio for poor outcome was 1.411, with a 95% confidence interval of 1.226 to 1.625. Straight sinus thrombosis had an adjusted odds ratio of 4.525, with a 95% confidence interval of 2.267 to 9.031.

Age was also independently associated with a higher odds ratio of 1.041 per year, while coma and intracerebral hemorrhage were associated with odds ratios of 8.127 and 2.397, respectively. These estimates quantify associations in the analyzed cohort; the observational design cannot establish that BAR or any imaging feature caused the outcome. The investigators used the five independent predictors to construct a nomogram, a graphical tool that assigns points to a patient’s age, BAR, clinical status and imaging findings and converts their sum into an estimated probability of poor functional outcome.

In a nested comparison, a model containing the clinical and radiological predictors without BAR had an AUC of 0.680 in the derivation cohort and 0.764 in the validation cohort. Adding BAR raised those values to 0.900 and 0.893, respectively, indicating better discrimination within this dataset. The BAR-containing nomogram also had Brier scores of 0.068 in the derivation cohort and 0.076 in the validation cohort, with calibration curves showing close agreement between predicted and observed risks across probability ranges.

The comparison indicates that BAR added predictive information to the measured clinical and radiological variables, but it does not establish that the nomogram improves treatment decisions or patient outcomes. Decision-curve analysis suggested that the BAR-containing model provided greater net benefit than the model without BAR across a range of clinically meaningful threshold probabilities in both cohorts. Additional analyses of the full sample recovered the same five independent predictors.

Ten-fold cross-validation and 1,000 bootstrap resampling iterations also produced stable optimism-corrected estimates for discrimination, Brier score and calibration slope. The analysis therefore supports the internal consistency of the model, but it does not show that using the nomogram would improve treatment decisions or patient outcomes. The study evaluated prediction, not the effect of a clinical intervention, and the favorable AUC values should be interpreted as performance within the study’s data rather than as a guarantee of accuracy in other hospitals or populations.

Several limitations constrain how far the findings can be generalized. The model has not yet been tested in independent cohorts from other institutions or healthcare systems, so its external calibration and clinical usefulness remain uncertain. Sampling was retrospective, and blood collection within 24 hours of admission did not standardize the interval between symptom onset, treatment and blood drawing.

Hydration changes and early therapeutic interventions may therefore have influenced blood urea nitrogen or albumin measurements. The retrospective design is also vulnerable to selection bias, despite prespecified exclusions, and the relatively small number of poor outcomes, 88 in the full sample, limits statistical precision. The findings should accordingly be regarded as an internally validated association and prediction model awaiting multicenter external testing.

Even with those constraints, the study points to BAR as a potentially useful addition to imaging-based assessment in CVST. Because both laboratory measurements are already obtained in routine hospital care, BAR may help translate existing information into a more individualized risk estimate.

Subject of Research: Prognostic value of the blood urea nitrogen-to-serum albumin ratio with clinical and radiological features in cerebral venous sinus thrombosis

Article Title: Prognostic model integrating the blood urea nitrogen-to-serum albumin ratio and radiological features for poor functional outcome in cerebral venous sinus thrombosis

Article References: Zhao, J., Liu, K., Li, S., Liu, H., Xu, Y., Xia, Z., & Song, B. (2026). Prognostic model integrating the blood urea nitrogen-to-serum albumin ratio and radiological features for poor functional outcome in cerebral venous sinus thrombosis. Frontiers in Neurology, 17, Article 1953972. https://doi.org/10.3389/fneur.2026.1953972

Image Credits: AI Generated

DOI: 10.3389/fneur.2026.1953972

Keywords: cerebral venous sinus thrombosis, blood urea nitrogen, serum albumin, prognostic model, nomogram, straight sinus thrombosis, intracerebral hemorrhage, functional outcome, clinical biomarkers, internal validation, Prognostic, model