Supplementary Material for: Development and validation of a prediction model for 30-day mortality and functional outcome in patients with primary brainstem hemorrhage.

Introduction: Primary brainstem hemorrhage (PBSH) is the most fatal subtype of intracerebral hemorrhage and associated with poor prognosis. We aimed to develop a prediction model for predicting 30-day mortality and functional outcome in patients with PBSH. Methods: We reviewed records of 642 consecutive patients with first-time PBSH from three hospitals between 2016 and 2021. Multivariate logistic regression was used to establish a nomogram in a training cohort. Cutoff points of the variables were determined by receiver operating characteristic curve analysis, and certain points were assigned to these predictors to produce the PBSH score. The nomogram and PBSH score were compared with other scoring systems of PBSH. Results: Five independent predictors, comprised of temperature, pupillary light reflex, platelet-to-lymphocyte ratio (PLR), Glasgow Coma Scale (GCS) score on admission, and hematoma volume, were incorporated to construct the nomogram. The PBSH score consisted of 4 independent factors with individual points assigned as follows: temperature, ≥38℃(=1 point), <38℃(=0 points); pupillary light reflex, absence (=1 point), presence (=0 points); GCS score 3 to 4 (=2 points), 5 to 11 (=1 point), and 12 to 15 (=0 points); PBSH volume >10 mL (=2 points), 5 to 10 mL (=1 point), and <5 mL (=0 points). Results showed that the nomogram was discriminative in predicting both 30-day mortality [AUC of 0.924 in the training cohort, and 0.931 in the validation cohort] and 30-day functional outcome [AUC of 0.887]. The PBSH score was discriminative in predicting both 30-day mortality [AUC of 0.923 in the training cohort, and 0.923 in the validation cohort] and 30-day functional outcome [AUC of 0.887]. The prediction performances of the nomogram and the PBSH score were superior to the intracranial hemorrhage (ICH) score, primary pontine hemorrhage (PPH) score, and new PPH score. Conclusions: We developed and validated two prediction models for 30-day mortality and functional outcome in patients with PBSH. The nomogram and PBSH score could predict 30-day mortality and functional outcome in PBSH patients.