Procedures
ventricular mass, proteinuria
CUFF
On the day of baseline assessments (day 0), eligible participants, following consent, underwent standardised measurement of blood pressure, echocardiography, and other study-related investigations, including measurement of plasma creatinine. Assessments were performed in dedicated clinical research facilities where possible, with participants aware of planned trial-related assessments.After randomisation, antihypertensive treatment in children whose blood pressure was not at the target level was commenced or modified to achieve the allocated target. For the intensive treatment group, the systolic office blood pressure target was lower than the 40th percentile (Z score –0·26), and for the standard treatment group it was between the 50th and 75th percentile (Z score 0·00–0·67). ACE inhibitors or ARBs were used as first-line agents, with the dose titrated every 2–4 weeks to achieve the target blood pressure levels. In cases in which children were on drugs other than ACE inhibitors or ARBs, an ACE inhibitor or ARB was substituted for another class of drug (with no washout period). Following ACE inhibitors or ARBs, the following drugs were used based on physicians' preferences to achieve target blood pressure: calcium channel blockers, β-receptor blockers, diuretics, or Data were collected by means of a standardised data collection form, with subsequent data entry into a dedicated web-based database (MedSciNet). At each follow-up visit, height, weight, blood pressure, antihypertensive medication, antihypertensive drug adherence, concomitant medications, and adverse outcomes were recorded. Laboratory data (haemoglobin, urea, creatinine, electrolytes, albumin, calcium, phosphate, intact parathyroid hormone, and proteinuria) were obtained at baseline and every year thereafter, with additional renal function assessments after an increase in dose of ACE inhibitors or ARBs, or as deemed necessary by the clinician.Office blood pressure was measured by a trained staff member (physician or nurse) and was measured by the same person on each child where possible. Patients were required to rest for at least 5 min in a seated position, systolic blood pressure was initially confirmed by palpation, and then the blood pressure was measured three times in quick succession using auscultation and aneroid sphygmomanometer with an appropriately sized cuff by inflating the cuff higher than systolic blood pressure. Cuff size was selected by ensuring cuff bladder length and width according to standard guidelines.Transthoracic echocardiograms were acquired at baseline and at annual intervals by a core team of experienced echocardiographers according to a standardised research protocol. To reduce inter-observer error, investigators travelled to all external centres from the lead centre (Evelina London Children's Hospital, King's College London) and performed all study-related cardiovascular assessments. Each echocardiogram was transferred in DICOM format and stored on a database in the Clinical Research Facilities, St Thomas' Hospital, London, UK, where a single masked investigator (HG) performed the overall image analysis for the primary outcome without knowledge of allocation to treatment group. The intra-observer coefficient of variation for this investigator was 8·5% for left ventricular mass and 7·1% for relative wall thickness. Left ventricular mass varies widely across the paediatric age range (0−16 years). Therefore, to allow standardisation, it is expressed as left ventricular mass index (LVMI; left ventricular mass in grams divided by height in metres raised to the allometric power of 2·7 [g/m