Association Between Admission Serum Phosphate Level and All-Cause Mortality Among Patients with Spontaneous Intracerebral Hemorrhage

Background: Hypophosphatemia was reported to frequently occur in patients with nontraumatic intracranial hemorrhage (ICH); however, the correlation between hypophosphatemia and outcomes of ICH remains unclear. This study aimed to examine the association between admission serum phosphate and all-cause mortality among patients with mild- moderate spontaneous ICH (sICH). Methods: A total of 851 patients with sICH were enrolled. Serum phosphate was acquired within 24 hours on admission, and participants were divided according to phosphate quartiles. The primary outcome was all-cause mortality within 90 days, and univariate and multivariate models were employed to estimate the mortality risk. Results: There were significant differences among sICH patients with different phosphate quartiles in terms of age, diastolic blood pressure (DBP), activated partial thromboplastin time (APTT), platelet count, and incidence of respiratory failure events on admission (P < 0.05). Log rank test showed a significant difference in the mortality risk among sICH patients with each phosphate quartile. Univariate Cox regression analysis revealed that age, smoking, DBP, APTT, NIH stroke scale (NIHSS) score, hematoma volume and serum phosphate might be associated with the 90-day all-cause mortality in patients with sICH (P < 0.05). Multivariable Cox regression analysis showed that the crude mortality was 4.3-fold greater in sICH patients with serum phosphate Q1 than those with Q4 (P < 0.001), and remained 3.18-fold higher after adjusting for age, smoking, DBP, APTT, NIHSS score, hematoma volume and early withdrawal of life-sustaining therapy (P = 0.011). Representative operating curve (ROC) analysis showed that admission serum phosphate was predictable for all-cause mortality within 90 days in patients with sICH (area under the ROC = 0.628, P < 0.001). Conclusion: Low admission serum phosphate is strongly associated with a high risk of mortality in patients with mild-moderate sICH, and hypophosphatemia may be a prognostic marker for all-cause mortality in patients with mild-moderate sICH.