Success of new treatment halts international blood pressure drug trial

An international trial comparing blood-pressure lowering treatments has been stopped early due to the significantly better performance of one of the treatments in the trial.

The 19,000 patient Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) has been comparing a new treatment strategy for hypertension against an old one, in order to discover which is better at preventing various cardiovascular events such as heart attacks and strokes.

The older treatment strategy based on the beta-blocker, atenolol and the thiazide diuretic, bendroflumethiazide was compared with a newer treatment strategy using the calcium channel blocker, amlodipine, and the angiotensin converting enzyme inhibitor, perindopril.

The blood pressure part of trial has been stopped because of cardiovascular benefits in favour of the newer calcium channel blocker plus angiotensin converting enzyme inhibitor treatment when compared with the beta-blocker, atenolol and the thiazide diuretic, bendroflumethiazide.

This announcement signals the end of the main clinical elements of the ASCOT trial, launched in 1997.

ASCOT study co-chairmen Björn Dahlöf, from the Sahlgrenska University Hospital, Östra, Sweden, and Peter Sever from Imperial College London, UK, comment: “This is excellent news for the many people who suffer from high blood pressure. Although at the moment we are unable to provide any definite figures on the effectiveness of the new treatments compared with the old, we have seen important significant differences.”

The Steering Committee of ASCOT accepted on 18 November the recommendation of its Data Safety Monitoring Board that the blood pressure arm of the trial should be stopped and the majority of patients have now been informed.

The complete results of the ASCOT trial will be made available when all data up to and including the last individual patient visit have been collected and analysed. Investigators and patients will be informed of the final results of ASCOT when these data become available. The results will be published in the scientific press.

Over the next few months all ASCOT patients will be seen for a final visit, when they will be given advice about future treatment of their hypertension.

Prior to their final visit, all patients are advised to stay on their existing drugs until they see their trial physician, to ensure their blood pressure remains controlled. The ASCOT trial doctors remind patients that sudden withdrawal of any treatment regimen could be harmful to them.

Of over 19,000 patients randomised to the two different blood pressure strategies, approximately 10,000 patients were also randomised to treatment with either atorvastatin or placebo in the ASCOT Lipid Lowering Arm (ASCOT-LLA). The ASCOT-LLA was stopped prematurely in October 2002, as a result of substantial benefits associated with statin use in the prevention of heart attacks and strokes.

The principal sponsor of ASCOT is Pfizer Inc, New York. Support has also been provided by Servier Research Group, Paris and Leo Laboratories, Copenhagen.