Prior antiplatelet therapy and haematoma expansion after primary intracerebral haemorrhage: an individual patient-level analysis of CLEAR III, MISTIE III and VISTA-ICH

OBJECTIVE: To evaluate the relationship between prior antiplatelet therapy (APT) and outcomes after primary intracerebral haemorrhage (ICH), and assess if it varies by haematoma location. METHODS: We pooled individual patient data from the Virtual International Stroke Trials Archive-ICH trials dataset, Clot Lysis: Evaluating Accelerated Resolution of Intraventricular Hemorrhage III trial and the Minimally Invasive Surgery Plus Alteplase for Intracerebral Hemorrhage Evacuation Phase III trial. The exposure was APT preceding ICH diagnosis. The primary outcome was haematoma expansion at 72 hours. Secondary outcomes were admission haematoma volume, all-cause mortality, death or major disability (modified Rankin Scale (mRS) score ≥4) and shift in mRS distribution. Mixed-effects models were used to assess the relationship between APT and outcomes. Secondary analyses were stratified by ICH location and study cohort. RESULTS: Among 1420 patients with ICH, there were 782 (55.1%) lobar and 596 (42.0%) deep haemorrhages. APT was reported in 284 (20.0%) patients. In adjusted regression models, prior APT was not associated with haematoma expansion (OR, 0.97; 95% CI 0.60 to 1.57), major disability or death (OR, 1.05; 95% CI 0.61 to 1.63), all-cause mortality (OR, 0.89; 95% CI 0.47 to 1.85), admission haematoma volume (beta, -0.17; SE, 0.09; p=0.07) and shift in mRS (p=0.43). In secondary analyses, APT was associated with admission haematoma volume in lobar ICH (beta, 0.25; SE, 0.12; p=0.03), but there was no relationship with other ICH outcomes when stratified by haematoma location or study cohort. CONCLUSIONS: In a large heterogeneous cohort of patients with ICH, prior APT was not associated with haematoma expansion or functional outcomes after ICH, regardless of haematoma location. APT was associated with admission haematoma volumes in lobar ICH.