Neutrophil counts and the risk of first stroke in general hypertensive adults

We aimed to investigate the association between neutrophil counts and first stroke and examine possible effect modifiers among treated hypertensive adults. This is a post hoc analysis of the China Stroke Primary Prevention Trial (CSPPT). A total of 11,878 hypertensive adults with data on neutrophil counts at baseline were included in the current study. The primary outcome was first stroke. During a median follow-up of 4.5 years, 414 (3.5%) participants experienced a first stroke, including 358 with ischemic stroke, 55 with hemorrhagic stroke and one with uncertain type of stroke. Compared with participants in quartile 1 (<2.9 × 10⁹/L) of neutrophil counts, those in the upper quartiles (quartile 2-4 [≥2.9 × 10⁹/L]) had a significantly higher risk of first stroke (HR, 1.35; 95% CI: 1.02, 1.78) or first ischemic stroke (HR, 1.38; 95% CI: 1.02, 1.86). Moreover, a strong positive association between neutrophil counts and first ischemic stroke was found in participants with total homocysteine (tHcy) levels <15 μmol/L (HR, 1.74; 95% CI: 1.17, 2.58; vs. ≥15 μmol/L; HR, 0.91; 95% CI: 0.57, 1.46, P interaction = 0.042) at baseline or time-averaged mean arterial pressure (MAP) ≥102 mmHg (median) (HR, 1.92; 95% CI: 1.27, 2.89; vs. <102 mmHg; HR, 0.89; 95% CI: 0.57, 1.41, P interaction = 0.015) during the treatment period. However, no such association between neutrophil counts and first hemorrhagic stroke was found. In summary, high baseline neutrophil counts were associated with an increased risk of first ischemic stroke among hypertensive patients, especially in those with low tHcy at baseline or high time-averaged MAP during the treatment period.