Randomisation and masking
Participants were randomly assigned (1:1) to receive standard treatment or intensive treatment by the chief investigator (MDS) using a rapid, secure, web-based randomisation system developed in house by the King's Clinical Trials Unit (King's College London). Randomisation was stratified according to clinical centre. Participants and recruiting clinicians were informed of the participant's allocation and trial-related systolic blood pressure targets electronically. Therefore, no unblinding or code breaking was required. Clinicians performing investigations were masked to participants' systolic blood pressure percentile and target, and the trial team and recruiters were masked to results.