or intramuscular with compartment syndrome, or bleed- ing causing a fall in haemoglobin concentration of 1·24 units or more, or leading to transfusion of two or more units of whole blood or red cells. Stroke was defi ned by the WHO defi nition14 as rapidly developing clinical signs of focal (or global) disturbance of cerebral function, lasting more than 24 h or leading to death, with no apparent cause other than that of vascular origin.
Statistical analysis We planned to enrol 250 participants on the basis of observational studies.2–4 We did no interim analyses. All enrolled patients were included in the intention-to- treat population. We also did a per-protocol analysis, which excluded any patient who did not meet inclusion criteria for any reason, including failure to confi rm diagnosis of dissection on central review of imaging. We calculated exact CIs with the binomial (Clopper-Pearson) exact method. We compared the treatment eff ect in each group by exact logistic regression (Stata, version 13). We did the other analyses with SPSS (version 20). We did power calculations to estimate the sample size needed for a defi nitive phase 3 trial with an online power calculator. These calculations were based on the combined endpoint of stroke, death, and major bleeding, with a power of 0·8 and a p value of 0·05. This trial is registered with EudraCT (2006-002827-18) and ISRN (CTN44555237) and was adopted by the English National Institute for Health Research Clinical Research Network (2181).
Role of the funding source The funder had no role in study design, data collection, analysis, or interpretation, writing of the report, or the decision to submit for publication. All authors had full access to all the data in the study. The fi nal decision to submit the report for publication was made by HSM.
Results We recruited 250 patients between Feb 24, 2006, and June 17, 2013. 118 had carotid dissection and 132 had vertebral arterial dissection. Mean time to randomisation was 3·65 days (SD 1·91). 174 (70%) of participants were male. Mean age was 49 years (SD 12, range 18–87). 126 participants were randomly assigned to antiplatelet treatment and 124 to anticoagulation treatment (fi gure). The major presenting symptoms were cerebral ischaemic in 224 patients (195 ischaemic stroke, 29 transient ischaemic attack) and local symptoms in 26 patients (22 headache, 22 neck pain, four Horner’s syndrome). Table 1 shows baseline characteristics. All patients were followed up for 3 months. In the antiplatelet group, 28 (22%) of 126 patients received aspirin alone, 42 (33%) received clopidogrel alone, one (1%) received dipyridamole alone, 35 (28%) received aspirin and clopidogrel, and 20 (16%) received aspirin and dipyridamole. In the anticoagulant group,
112 (90%) of 124 patients received heparin and warfarin and 12 (10%) received warfarin alone. Original brain imaging and angiographic imaging was reviewed for all patients throughout the study and before the database was locked. Dissection was confi rmed for 198 patients (102 in the antiplatelet group, 96 in the anticoagulant group). For one patient in the antiplatelet group, although recruited within 7 days, randomisation was not done until day 9 because of a technical error. Therefore the per-protocol analysis included 197 patients (101 in the antiplatelet group, 96 in the anticoagulant group).