Higher total white blood cell and neutrophil counts linked to increased risk of fatal stroke

According to a new study, the WBC count, particularly the Neutrophil (NEUT) count, is associated with an increased risk of fatal all stroke occurrence. Longitudinal increases in WBC count and NEUT count of more than 25% were also associated with an increased risk of fatal all stroke occurrence in the elderly population.

This study was conducted by Zhi-bing Hu and team, results of which are published in the Journal of BMC Neurology.

Chronic inflammatory diseases are associated with an increased risk of stroke. The white blood cell (WBC) count is a common inflammatory response marker. However, it is unclear whether WBC count, subpopulations, and dynamic changes in WBC count are related to the risk of fatal stroke in a relatively healthy elderly population. Therefore, the researchers wanted to look at the relationships between WBC counts, subpopulations, and changes, and the risks of fatal all stroke, fatal ischemic stroke, and fatal hemorrhagic stroke in a relatively healthy elderly population in southern China.

In this study, 27,811 people without a history of stroke were included and followed up on for an average of 11.5 (standard deviation = 2.3) years. Following a review of available records, 503 stroke deaths were recorded (ischemic 227, hemorrhagic 172, and unclassified 104) Cox proportional hazards regression was used to examine the relationships between WBC count, subpopulations, and dynamic changes (two-phase examination from baseline to first follow-up) and the risk of fatal all stroke, fatal ischemic stroke, and fatal hemorrhagic stroke.

The findings of this study are:

1. When it came to the WBC count and the risk of fatal stroke, restricted cubic splines revealed an atypically U-shaped relationship between the WBC count and the risk of fatal all stroke occurrence.

2. Participants with the highest WBC count (> 7.2*109/L) had a 53 and 67% increased risk for fatal all stroke and fatal hemorrhagic stroke, respectively, compared to those in the lowest quartile (> 3.0*109/L); compared to those in the lowest quartile (> 3.0*109/L), participants with the highest NEUT count (> 4.5*109/L) had a 45 and 65% increased risk for fatal.

3. With the addition of a C-reactive protein adjustment, the WBC count (4 10*109/L) and the NEUT count yielded the same results as for all stroke and ischemic stroke, but not for hemorrhagic stroke.

4. In terms of dynamic changes in the WBC count and the risk of fatal stroke, compared to the stable group, groups with a 25% increase in the WBC count and NEUT count had a 60% and 45% increased risk of fatal all stroke occurrence, respectively.

IN conclusion, higher WBC and NEUT counts were associated with an increased risk of fatal all stroke in this first cohort study of relatively healthy Chinese individuals in one of China's most economically developed cities. Longitudinal WBC and NEUT count increases of more than 25% were also linked to a significantly increased risk of fatal stroke. The occurrence of fatal strokes in China may forewarn the burden of pre-existing chronic low-grade systemic inflammation, particularly among the elderly populations of large cities.

Reference:

Hu, Zb., Lu, Zx., Zhu, F. et al. Higher total white blood cell and neutrophil counts are associated with an increased risk of fatal stroke occurrence: the Guangzhou biobank cohort study. BMC Neurol 21, 470 (2021). https://doi.org/10.1186/s12883-021-02495-z