Protocol - Introduction

Balloon angioplasty and/or endovascular stenting are being used with increasing frequency among patients with atherosclerotic renovascular disease (ARVD). Although these procedures do result in obvious improvements in arterial patency, there is currently no good evidence that they delay progressive decline of renal function. However, since revascularisation is associated with a definite procedural risk, such a procedure might not be justified if the benefits to renal function were small and outweighed by the procedural hazards. The ASTRAL trial is designed to address the issue of whether renal arterial revascularisation with balloon angioplasty and/or endovascular stenting can safely prevent progressive renal failure among a wide range of patients with ARVD.

Patients are eligible for the ASTRAL trial if the medical team responsible for their hospital management is substantially uncertain about whether to offer revascularisation in addition to any medical management that is currently considered appropriate in their own hospital. Angiographic and other relevant criteria relating to an eligible and consenting patient will be considered by the doctor(s) responsible for their care, and the technical details of any potential procedure agreed. Randomisation will then proceed through a short telephone call to the ASTRAL Trial Office.

To make large-scale recruitment feasible, and to maximise the clinical relevance of the eventual findings, the trial is designed to fit in with routine practice with a minimum of extra tests and investigations over those that would normally be required. About 1000 patients (500 revascularisation versus 500 medical treatment alone) will be recruited into the ASTRAL trial over a 4 year period and followed for a minimum of 1 year. The primary measure of efficacy will be the difference in mean rates of progression as assessed by reciprocal creatinine plots based on annual assessments. Secondary measures of efficacy will include: blood pressure; urinary protein excretion; serious vascular events (such as myocardial infarction or stroke); and a single estimate of angiographic patency at about 12 months.

The ASTRAL Trial Office will assist the local co-ordinator at each centre to gain research ethics committee approval and will help resolve any local problems that may be encountered in trial participation. The ASTRAL Trial Office also is responsible for the collection of data and for data analyses. During the study, the accumulating data from ASTRAL - and other relevant studies - will be regularly reviewed by an independent data monitoring committee who will advise the Trial Steering Committee if clear evidence of worthwhile benefit emerges before the scheduled recruitment is complete.

The success of ASTRAL depends entirely on the wholehearted collaboration of a large number of doctors, nurses and others. For this reason, chief credit for the main results will be given not to the central organisers but to all those who have collaborated in the trial.