Thrombocytopenia and In-hospital outcomes in patients with acute ischemic stroke undergoing intravenous thrombolysis: Findings from a nationwide registry study in China.

• Platelet count <100 × 10⁹/L is a reasonable contraindication for rt-PA intravenous thrombolysis. • No randomized controlled experiments confirmed this conclusion. • The thresholds of platelet count are based on expert opinion as evidenced by large-scale hospital-based study. • People with thrombocytopenia are at high risk of symptomatic intracranial hemorrhage. Our study aimed to evaluate the associations between platelet count (PC) and in-hospital outcomes for patients with stroke after rt-PA intravenous thrombolysis. We identified patients who had been hospitalized with a primary diagnosis of stroke and had received rt-PA intravenous thrombolysis from June 2015 to July 2019 at participating hospitals in the Chinese Stroke Center Alliance. PC measured before intravenous thrombolysis was categorized into the following four groups: severe thrombocytopenia (PC < 100 × 10⁹/L), mild thrombocytopenia (100 ≤ PC < 150 × 10⁹/L), normal PC (150 ≤ PC ≤ 450 × 10⁹/L), and thrombocythemia (PC > 450 × 10⁹/L). Outcomes were determined from clinical data collected during hospitalization. The primary clinical outcome was symptomatic intracranial hemorrhage (sICH). Secondary outcomes were mortality, bleeding events, gastrointestinal (GI) hemorrhage, and in-hospital stroke recurrence. We used multivariate logistic regression models to evaluate the associations between PC and outcomes. We included 44,882 individuals with a median age of 66 years, of whom 34.7 % were female, 951 (2.1 %) had severe thrombocytopenia, 7218 (16.1 %) had mild thrombocytopenia, 36,522 (81.4 %) had a normal PC, and 191 (0.4 %) had thrombocythemia. Both severe and mild thrombocytopenia groups had higher risks of bleeding events (adjusted OR 1.30; 95 % CI,1.01-1.67; p = 0.045; adjusted OR 1.32; 95 % CI,1.19-1.46; p < 0.001) and sICH (adjusted OR 1.48;95 % CI,1.13-1.94; p = 0.005; adjusted OR 1.43;95 % CI,1.27-1.60; p < 0.001) than the normal PC group. Patients with 100 ≤ PC < 150 × 10⁹/L also had a higher risk of in-hospital stroke recurrence (adjusted OR 1.12; 95 % CI,1.02-1.22; p = 0.02). Intravenous thrombolysis brings a high risk of sICH given PC < 150 × 10⁹/L, especially PC < 100 × 10⁹/L. It indicated that PC < 100 × 10⁹/L is a reasonable contraindication to thrombolysis. [ABSTRACT FROM AUTHOR]