High Leukocyte Count and Risk of Poor Outcome After Subarachnoid Hemorrhage: A Meta-Analysis

Subarachnoid hemorrhage is (SAH) is a devastating neurologic emergency often associated with systemic inflammatory response. Many reports have demonstrated an association between elevated inflammatory markers and poor outcome. We performed an observational study and a meta-analysis of the impact of high leukocyte count on outcome after SAH.

We initially retrospectively analyzed 147 patients with SAH through assessment of medical records database. Poor outcome was defined as modified Rankin Scale score >3. Then, we performed a systematic literature search of PubMed, EMBASE, and the Cochrane Library. Prospective and retrospective studies were included if they assessed impact of leukocytosis on outcome after aneurysmal SAH in adults. We used a random-effect model and quality-effect model, based on the study quality assessment tool, an adapted version of inventory to assess quality of intervention studies.

Within our initial observational study, a total of 63 (42.86%) patients had poor treatment outcome. Those patients significantly more often had elevated white blood cell count upon admission (60.32 vs. 40.48%; P = 0.02). A literature search identified 10,119 articles, of which 13 were included into the meta-analysis. Pooled impact of high leukocyte count on outcome was odds ratio 1.42 (95% confidence interval 1.24-1.63) for random-effect model and OR 1.86 (95% confidence interval 1.46-2.36) for the quality-effect model. However, the studies were heterogenous (I = 54%).

Elevated white blood cells is a marker of poor outcome after SAH. Despite the fact that it is unlikely to be causative, it may be treated as a useful risk predictor.