Background This is an update of the Cochrane Review last published in 2017. Survivors of stroke due to intracerebral haemorrhage (ICH) are at risk of major adverse cardiovascular events (MACE). Antithrombotic (antiplatelet or anticoagulant) treatments may lower the risk of ischaemic MACE after ICH, but they may increase the risk of bleeding. Objectives To determine the overall effectiveness and safety of antithrombotic drugs on MACE and its components for people with ICH. Search methods We searched the Cochrane Stroke Group Trials Register (5 October 2021). We also searched the Cochrane Central Register of Controlled Trials (CENTRAL: the Cochrane Library 2021, Issue 10), MEDLINE Ovid (from 1948 to October 2021) and Embase Ovid (from 1980 to October 2021). The online registries of clinical trials searched were the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (5 October 2021). We screened the reference lists of included randomised controlled trials (RCTs) for additional, potentially relevant RCTs. Selection criteria We selected RCTs in which participants with ICH of any age were allocated to a class of antithrombotic treatment as intervention or comparator. Data collection and analysis In accordance with standard methodological procedures recommended by Cochrane, two review authors assessed each selected RCT for its risk of bias and extracted data independently. The primary outcome was a composite of MACE, and secondary outcomes included death, individual components of the MACE composite, ICH growth, functional status and cognitive status. We estimated effects using the frequency of outcomes that occurred during the entire duration of follow-up and calculated a risk ratio (RR) for each RCT. We grouped RCTs separately for analysis according to 1) the class(es) of antithrombotic treatment used for the intervention and comparator, and 2) the duration of antithrombotic treatment use (short term versus long term). We pooled the intention-to-treat populations of RCTs using a fixed-effect model for meta-analysis, but used a random-effects model if RCTs differed substantially in their design or there was considerable heterogeneity (I-2 >= 75%) in their results. We applied GRADE to assess the certainty of the evidence. Main results We identified seven new completed RCTs for this update, resulting in the inclusion of a total of nine RCTs based in secondary care, comprising 1491 participants (average age ranged from 61 to 79 years and the proportion of men ranged from 44% to 67%). The proportion of included RCTs at low risk of bias, by category was: random sequence generation (67%), allocation concealment (67%), performance (22%), detection (78%), attrition (89%), and reporting (78%). For starting versus avoiding short-term prophylactic dose anticoagulation after ICH, no RCT reported MACE. The evidence is very uncertain about the effect of starting short-term prophylactic dose anticoagulation on death (RR 1.00, 95% CI 0.59 to 1.70, P = 1.00; 3 RCTs; very lowcertainty evidence), venous thromboembolism (RR 0.84, 95% CI 0.51 to 1.37, P = 0.49; 4 RCTs; very low-certainty evidence), ICH (RR 0.24, 95% CI 0.04 to 1.38, P = 0.11; 2 RCTs; very low-certainty evidence), and independent functional status (RR 2.03, 95% CI 0.78 to 5.25, P = 0.15; 1 RCT; very low-certainty evidence) over 90 days. For starting versus avoiding long-term therapeutic dose oral anticoagulation for atrial fibrillation after ICH, starting long-term therapeutic dose oral anticoagulation probably reduces MACE (RR 0.61, 95% CI 0.40 to 0.94, P = 0.02; 3 RCTs; moderate-certainty evidence) and probably reduces all major occlusive vascular events (RR 0.27, 95% CI 0.14 to 0.53, P = 0.0002; 3 RCTs; moderate-certainty evidence), but probably results in little to no difference in death (RR 1.05, 95% CI 0.62 to 1.78, P = 0.86; 3 RCTs; moderate-certainty evidence), probably increases intracranial haemorrhage (RR 2.43, 95% CI 0.88 to 6.73, P = 0.09; 3 RCTs; moderate-certainty evidence), and may result in little to no diMerence in independent functional status (RR 0.98, 95% CI 0.78 to 1.24, P = 0.87; 2 RCTs; low-certainty evidence) over one to three years. For starting versus avoiding long-term antiplatelet therapy after ICH, the evidence is uncertain about the effects of starting long-term antiplatelet therapy on MACE (RR 0.89, 95% CI 0.64 to 1.22, P = 0.46; 1 RCT; moderate-certainty evidence), death (RR 1.08, 95% CI 0.76 to 1.53, P = 0.66; 1 RCT; moderate-certainty evidence), all major occlusive vascular events (RR 1.03, 95% CI 0.68 to 1.55, P = 0.90; 1 RCT; moderate-certainty evidence), ICH (RR 0.52, 95% CI 0.27 to 1.03, P = 0.06; 1 RCT; moderate-certainty evidence) and independent functional status (RR 0.95, 95% CI 0.77 to 1.18, P = 0.67; 1 RCT; moderate-certainty evidence) over a median follow-up of two years. For adults within 180 days of non-cardioembolic ischaemic stroke or transient ischaemic attack and a clinical history of prior ICH, there was no evidence of an eMect of long-term cilostazol compared to aspirin on MACE (RR 1.33, 95% CI 0.74 to 2.40, P = 0.34; subgroup of 1 RCT; low-certainty evidence), death (RR 1.65, 95% CI 0.55 to 4.91, P = 0.37; subgroup of 1 RCT; low-certainty evidence), or ICH (RR 1.29, 95% CI 0.35 to 4.69, P = 0.70; subgroup of 1 RCT; low-certainty evidence) over a median follow-up of 1.8 years; all major occlusive vascular events and functional status were not reported. Authors' conclusions We did not identify beneficial or hazardous effects of short-term prophylactic dose parenteral anticoagulation and long-term oral antiplatelet therapy after ICH on important outcomes. Although there was a significant reduction in MACE and all major occlusive vascular events after long-term treatment with therapeutic dose oral anticoagulation for atrial fibrillation after ICH, the pooled estimates were imprecise, the certainty of evidence was only moderate, and effects on other important outcomes were uncertain. Large RCTs with a low risk of bias are required to resolve the ongoing dilemmas about antithrombotic treatment after ICH.
