Characterisation of the diagnostic window of serum glial fibrillary acidic protein for the differentiation of intracerebral haemorrhage and ischaemic stroke.

BACKGROUND

The rapid differentiation between intracerebral haemorrhage (ICH) and ischaemic stroke (IS) using biomarker testing would allow the prehospital, cause-specific management of stroke patients. Based on single measurements made during the acute phase of stroke, the value of serum glial fibrillary acidic protein (GFAP) was reported to be higher in ICH patients than in IS patients. The aim of the present study was to characterise the diagnostic window of serum GFAP for differentiating between ICH and IS.

METHODS

63 stroke patients admitted within 6 h of symptom onset were prospectively included. ICH (n = 18) and IS (n = 45) were diagnosed using brain imaging. Blood sampling was scheduled for 1, 2, 3, 4, 6, 12, 24 and 48 h after stroke onset (if applicable), and serum GFAP was measured using an ELISA test.

RESULTS

For the first 24 h after stroke, median GFAP values in IS patients remained below the detection limit. Between 2 and 6 h of stroke onset, serum GFAP was significantly higher in ICH patients than in IS patients (p < 0.001 for all 4 time points). According to a receiver operating characteristic curve analysis, the overall diagnostic accuracy of GFAP in differentiating between ICH and IS was >0.80 within the 2- to 6-hour time window. Two hours after stroke onset, serum GFAP values were significantly correlated with ICH volume (r = 0.755, p = 0.007).

CONCLUSIONS

The time window between 2 and 6 h after stroke onset is best for using GFAP to differentiate between ICH and IS. In the very early phase (i.e. <2 h), sensitivity for detecting ICH is low, thus hampering the application of GFAP as a near-patient test in the prehospital phase.