Platelet counts affect the prognostic value of homocysteine in acute ischemic stroke patients

Background and aims: The association between homocysteine and prognosis of ischemic stroke remains controversial, and the role of platelet count on the effects of homocysteine in the prognosis of ischemic stroke is still not elucidated. Methods: A total of 3229 acute ischemic stroke patients from the China Antihypertensive Trial in Acute Ischemic Stroke (CATIS) with homocysteine and platelet measurements were included in this analysis. They were prospectively followed up for death, recurrent stroke and vascular events within 1 year after acute ischemic stroke. Results: There was a significant interaction effect between platelet count and homocysteine level on death (p for interaction < 0.05) within 1 year after ischemic stroke. After multivariate adjustment, high homocysteine level was associated with increased risk of 1-year mortality in patients with low platelet level (hazard ratio, 1.70; 95% confidence interval, 1.01–2.88) but not in those with high platelet level (hazard ratio, 1.08; 95% confidence interval, 0.65–1.75). The addition of homocysteine to a model containing conventional risk factors improved risk prediction of 1-year death (net reclassification index 0.53%, p < 0.001; integrated discrimination improvement 0.07%, p < 0.001). Conclusions: High homocysteine may be merely an independent risk factor of death in ischemic stroke patients with low platelet levels. Further prospective studies from other populations and randomized clinical trials are needed to verify our findings and clarify the potential mechanisms.