STUDY DESIGN OF THE INTERNATIONAL STROKE TRIAL (IST), BASE-LINE DATA,AND OUTCOME IN 984 RANDOMIZED PATIENTS IN THE PILOT-STUDY

Background and purpose-To test the design and feasibility of a very la rge randomised controlled trial assessing the efficacy and safety of a ntithrombotic therapy started within 48 hours of symptom onset in pati ents with suspected acute ischaemic stroke. Design-Randomised controll ed multicentre open study, with a 3 x 2 factorial design, allocating p atients to: medium dose subcutaneous heparin (12 500 units twice per d ay), versus low dose subcutaneous heparin (5000 units twice per day) v ersus no heparin; and aspirin (300 mg daily) versus no aspirin. Treatm ent was given for two weeks or until discharge from hospital if sooner . Results-984 patients were randomised. CT was performed in 924 (94%) (before randomisation in 622/984 (63%)). Within 14 days: 97 patients h ad died (10%), 30 (3.0%) had a fatal or non-fatal recurrent ischaemic stroke, nine (0.9%) had fatal or non-fatal recurrent stroke due to int racranial haemorrhage, and eight (0.8%) had a fatal or non-fatal pulmo nary embolus. At six months, vital status was known for 975 patients ( 99%), of whom treatments. 210 (22%) were dead, 373 (38%) were alive bu t dependent, and 225 (23%) were independent but not fully recovered. C onclusions-The trial procedures ELIGIBILITY proved practicable and a w ide variety of patients were recruited. Sample size calculation based on the event rates confirmed that reliable evidence on the balance of risk and benefit of early antithrombotic therapy might require a study with more than 20000 patients. Recruitment rates in the pilot study i ndicated that if about 200 hospitals participated, recruitment could b e completed by 1997.