White blood cell count and clinical outcomes after intracerebral hemorrhage: The INTERACT2 trial.

Background: Increased inflammatory reaction can aggravate brain injury after acute intracerebral hemorrhage, but the clinical effect of such response is not fully understood. The aim of this study was to determine associations of peripheral white blood cell (WBC) count on clinical outcome among participants of the INTERACT2 study.

Methods: INTERACT2 was a randomized controlled trial of early intensive (target systolic level<140 mm Hg) compared to guideline-recommended (target systolic level < 180 mm Hg) blood pressure (BP) lowering in 2839 patients with acute ICH (<6h) and elevated systolic BP (150-220 mm Hg). Blood samples were collected on admission and WBC count was measured at local laboratories. The primary outcome was death or major disability, defined by scores 3-6 on the modified Rankin Scale at 90 days. Secondary outcome was death at 90 days. Associations of baseline WBC count and outcomes were evaluated in logistic regression models. INTERACT2 is registered with http://www.clinicaltrials.gov NCT00716079.

Results: There were 2630 participants with relevant data who were classified into quartiles of WBC counts (≤ 6.22, 6.24-7.89, 7.90-10.17, and ≥ 10.20 × 10(9)/L, respectively). Increased WBC count was associated with younger age, elevated body temperature, increased glucose level, stroke severity, larger baseline hematoma volume, and intraventricular extension. Risks of death or major disability at 90 days increased progressively with higher WBC count: frequencies of 49.9%, 52.0%, 52.3% and 58.1% for quartile groups, respectively (P=0.004 for trend). However, after adjustment for baseline clinical and imaging variables including age, sex, region, lipid lowering therapy, body temperature, glucose, systolic BP, heart rate, high NIHSS scores, volume and location of hematoma, intraventricular extension, time from onset to CT scan, and randomized treatment, the association between WBC count and primary outcome was no longer significant (P=0.426 for trend). Patients with increased WBC count had significantly higher risk of death (P=0.0003 for trend), but again the association was no longer significant after adjustment for baseline clinical and imaging variables.

Conclusions: Elevated WBC count on admission is not an independent prognostic variable in patients with acute ICH.