The website domain reflects its role for my own purpose only. Viewing of the webpages by others is not approved.
Main Index Site Developments
Patient Information Conditions of Use



---
Hypertension

Hypertension Trials- Implications and Controversies

A review of recent hypertension trials published in the Journal of the American College of Cardiology (2005;45:813-27) raised the following questions:

  • do some drugs have benefits beyond those obtained by lowering blood pressure?
  • are some drugs harmful in some respects and does this reduce the benefits obtained by lowering blood pressure?
  • clinical trials focus on end-points that can be evaluated over a relatively short time period (ie 4-5 years) but should we take a much longer term perspective attempting to alter disease processes? In other words, if we take a longer term perspective, we might consider lowering our threshold for treatment further to obtain benefits that can not be demonstrated in short-term trials.

This review refers to a meta-analysis on behalf of the National Institure of Clinical Excellence (NICE) in the United Kingdom. This meta-analysis would have been influenced by the findings of the largest trial, the ALLHAT trial- a trial which has been controversial in some respects.

Impact on coronary heart disease events: this analysis found that ACE-inhibitors and calcium channel blockers were equally effective in lowering CHD events by about 20 percent compared to placebo. In addition, there was no evidence that any one drug was superior to another, when compared "head to head".

The data on angiotensin receptor blockers is more sparse but there is no evidence from a number of trials, include LIFE, that these agents are any better than other agents in reducing coronary heart events.

Impact on stroke prevention: compared with placebo, ACE-inhibitors and calcium channel blockers reduced risk of stroke by about 28 to 38 percent. In this meta-analysis ACE-inhibitors were marginally less effective than conventional therapy when compared to placebo, which is surprising given the findings of the HOPE study and also PROGRESS, raising the possibility that the benefits seen in these latter trials was simply due to greater blood pressure reduction and not due to any specific properties of ACE-inhibitors. In addition, when compared "head to head" with conventional therapy there was no evidence of superior stroke prevention with ACE-inhibitors.

The meta-analysis, however, did suggest that calcium channel blockers were superior to other agents in stroke prevention. More superior results in terms of stroke prevention were also seen with use of angiotension blockers.

At the time this review was published the preliminary results of the ASCOT trial had not been presented.

This review also refers to other data which suggests that benefits continue to accrue with lowering of blood pressure to 115/75mmHg but there is no data for values below this. It seems possible, thus, that the benefits seen in HOPE and EUROPA were due to the small differences in blood pressure seen between ACE-inhibitor group and the usual therapy group. Of course, others have concluded that there small differences do not account for the demonstrated benefits and that ACE-inhibitors may have some specific properties that explain this benefit.

The review emphasises the need to consider the global risk of the patient. Patients at "higher" risk for events will benefit from anti-hypertensive therapy even if this is initiated with blood pressure measurements that might be classified as "mildly" elevated. This is similar to the current approach to dyslipidaemia, with lower thresholds for treatment of those at higher risk.

Hitesh Patel, Cardiologist

5th May, 2005

Users should read this document on "copyright" and "conditions of use".