Elevated bilirubin after acute ischemic stroke linked to the stroke severity

Abstract

Background: Our previous study demonstrated that the level of serum bilirubin after acute ischemic stroke (AIS) was correlated to the severity of stroke, also there has the evidence of hyperbilirubinemia prevalent in AIS. We aimed to identify the exact change of bilirubin in the early phase of AIS, and study if this kind of change linked to the severity of stroke.

Methods: Bilirubin and other biochemical indexes were measured in 608 AIS patients and 188 transient ischemic attack (TIA) patients which set as the control group. National Institutes of Health Stroke Scale (NIHSS) scores were assessed simultaneously with blood collection. First, the level of bilirubin and its distribution were compared between the AIS and control group. According to a cut-off point, we next analyzed the impacted factors of elevated bilirubin including the direct bilirubin (Dbil) and total bilirubin (Tbil), especially the correlation between elevated bilirubin and the severity of stroke. Finally, we compared the difference of concentration and percent of elevated bilirubin among the Oxford Community Stroke Project (OCSP) subtypes.

Results: The level of serum Dbil and Tbil was significantly higher in the AIS group than that in the TIA group. Different distribution was observed between the two groups, which manifested as the percent of low bilirubin level group was lower while high level group was higher in AIS than that in TIA, the p value were 0.043 and 0.078 in Dbil and Tbil, respectively. When the cut-off point of elevated bilirubin was selected as Dbil≥6.84 μmol/L and Tbil≥22.2 μmol/L, we found that both NIHSS score and relative severity of AIS were significantly associated with elevated bilirubin whenever in Dbil or Tbil, so did the OCSP subtypes. This trend was still maintained by multivariable logistic regression analysis adjust for relative influence factors. In regard of OCSP subtypes, the highest level of bilirubin was found in TACI, so did the highest rate of elevated bilirubin.

Conclusion: The serum levels of Dbil and Tbil were increased after AIS, which linked to the severity of stroke.

Keywords: Acute ischemic stroke; Bilirubin; Severity.