Statistical analysis plan for evaluating different intensities of blood pressure control in the ENhanced Control of Hypertension And Thrombolysis strokE stuDy

Background: The ENhanced Control of Hypertension And Thrombolysis strokE study (ENCHANTED) trial was initiated as a 2 × 2 partial-factorial active-comparison, prospective, randomized, open, blinded endpoint clinical trial to evaluate in thrombolysis-eligible acute ischemic stroke (AIS) patients whether: (1) Arm A – low-dose (0.6 mg/kg body weight) intravenous (iv) alteplase has noninferior efficacy and lower risk of symptomatic intracerebral hemorrhage (sICH) compared with standard-dose (0.9 mg/kg body weight) iv alteplase; and (2) Arm B – early intensive blood pressure (BP) lowering (systolic target 130–140 mmHg) has superior efficacy and lower risk of ICH compared with guideline-recommended BP control (systolic target <180 mmHg). Arm A was completed in 2016; Arm B is now concluding. Objective: To outline in detail and make public the predetermined statistical analysis plan (SAP) for the ‘BP control’ arm of this study. Methods: All data collected by participating researchers will be reviewed and formally assessed. Information pertaining to the baseline characteristics of patients, their process of care, and the delivery of treatments will be outlined, and for each item, statistically relevant descriptive elements will be described. For the trial outcomes, the most appropriate statistical comparisons to be made between groups are planned and described. Results: A SAP was developed for the results of the BP control arm of this study that is transparent, available to the public, verifiable, and predetermined before completion of data collection. Conclusions: We have developed a predetermined SAP for the ENCHANTED BP control arm to be followed to avoid analysis bias arising from prior knowledge of the study findings. Clinical trial registration: ClinicalTrials.gov (NCT01422616); ISRCTN Register (ISRCTN82387104); Australian New Zealand Clinical Trial Registry (ACTRN12611000236998); EU Clinical Trials Register (2011-005545-12); and Clinical Trials Registry – India (REF/2017/05/014334).