Results
Of the 4,036 patients with intracerebral hemorrhage, 2887 (71.5%) had eGFR < 90 mL/min/1.73 m2 (Figure 1). 169 (4.2%) patients were in the group with eGFR <15 mL/min/1.73 m2 or on dialysis.
Table 1 shows that more than two third (n=2677) of the patients with intracerebral hemorrhage were men. With a median age of 61.4 years, the age of study population increased as the eGFR level decreased. In general, prevalence rates of comorbidities, scores of NIHSS, systolic blood pressure and medication use prior to admission tended to be higher in groups with lower eGFR, whereas Hb levels were lower in groups with lower eGFR. Of the baseline comorbidities in all study patients, hypertension was the most prevalent comorbidity (86.6%), followed by diabetes mellitus, previous stroke, ischemic heart disease, atrial fibrillation, and congestive heart failure (1.21%).
The cumulative incidence rates of overall mortality in one year in patients with intracerebral hemorrhage increased as the eGFR level declined (P < 0.001). The proportional mortality rate was 38% greater in those with an eGFR of < 15 ml/min/1.73 m2 than in those with eGFR levels ≥ 90 mL/min/1.73m2 (Figure 2).
Both one-month mortality (N = 258) and one-year mortality (N=394) rates of patients with intracerebral hemorrhage were negatively associated with their eGFR levels at admission (Table 2 and 3). The one-month mortality rate increased as the eGFR levels decreased, from 1.5 per 1000 person-days in patients with eGFR levels ≥ 90 to 8.31 per 1000 person-days in patients with eGFR levels < 15 ml/min/1.73 m2. The adjusted HR was 4.59 (95% CI = 2.71, 7.78) for patients with eGFR levels < 15 ml/min/1.73 m2 compared to those with eGFR levels ≥ 90 mL/min/1.73m2. The corresponding adjusted HR of one-year mortality increased to 4.54 (95% CI = 2.59, 6.98) for those with eGFR levels < 15 ml/min/1.73 m2. Other risk factors associated with one-year mortality after intracerebral hemorrhage included female, age, non-hypertensive cause, atrial fibrillation, systolic blood pressure, NIHSS score at admission, warfarin use prior to admission (Table S1).
The area under the ROC curves for the eGFR level in predicting one-month mortality, and one-year mortality were 0.64 (Figure 3A), and 0.66 (Figure 3B) in patients with intracerebral hemorrhage, respectively.