Saturday, April 12, 2008

Blood pressure treatments

I would like to see all these treatments independently compared with placebo over an extended period. Do the pills make a difference to mortality? Only a double blind study could really tell us. It seems that Micardis has been shown in clinical trials to have anti-hypertensive effects only. Its effect on mortality is just speculation. The "survey which suggested" in the final paragraph below was obviously not a double-blind trial -- and surveys suggest many things that later turn out to be wrong. "But the leap from hypertension reduction to reduced mortality is a highly plausible speculation", someone might say. True. But even plausible speculation can be wrong, as we see in the second study below

Though it is never too late to treat high blood pressure, the sooner it is treated the less likelihood there is of patients suffering strokes, heart attacks, heart and kidney failure. Professor Graham MacGregor, chairman of the Blood Pressure Association, says that poor blood pressure control causes about 125,000 unnecessary strokes and heart attacks every year in the UK, about half of which prove fatal.

The therapeutic inclinations of British doctors are conservative. When prescribing for early, symptom-free high blood pressure, their thoughts are almost welded to the established habit of treating it with a diuretic thiazide tablet - the water pill - with or without a beta blocker. This combination was revolutionary when it was introduced, and it remains the treatment of choice for patients with a history of heart attacks, heart failure or difficult, atypical angina. However, there are now better ways to treat newly diagnosed blood pressure that achieve better results with less risk of side-effects.

The drawbacks of thiazide diuretics are that they increase a patient's likelihood of developing type 2 diabetes, and both they and beta blockers may be factors in causing impotence in men. The British Blood Pressure Association has adapted the NICE guidelines to take into account the newer drugs that control blood pressure with fewer side-effects. Patients currently taking beta blockers with or without the thiazides should never stop taking beta blockers without talking to their doctor. However, in the opinion of Professor MacGregor, they would be advised to discuss with their doctor whether it would help them to change to the newer drugs.

The question of the benefits afforded by careful selection of drugs to treat high blood pressure was a talking point at the recent meeting of American cardiologists in Chicago. The standard treatment pattern for patients under 55 with high blood pressure is either an ACE inhibitor or an ARB. There had been doubts over which was the better one to prescribe. A survey comparing Micardis (telmisartan) and ARB with a standard ACE inhibitor suggested that those high-risk patients taking Micardis suffered fewer side-effects, without any loss of effectiveness. The same trial, which included 25,600 people at high risk of a cardiovascular event, indicated that there was no advantage to taking both an ACE inhibitor and an ARB. Although a patient's blood pressure fell farther, the outcome was not improved and the side-effect profile was worse.

The other talking point at the Chicago meeting was a survey which suggested that elderly people - ie, the over-80s - with high blood pressure could still receive major benefits from having the condition treated, even if they had not done so in the past. With treatment, strokes were reduced by 30 per cent, heart failure by 64 per cent, and there was a 20 per cent reduction in death from all causes.


Cancer vaccine advance

FORMER Australian of the Year Ian Frazer has uncovered a clue as to why vaccines designed to kill cancer rarely work in people ¿ a discovery which may point the way towards boosting their effectiveness.

Scientists have been trialling vaccines in the treatment of patients with melanomas and kidney cancers but results have been disappointing. "They've worked in animal models but they didn't kill the cancer cells in people," Professor Frazer said.

The Brisbane scientist and colleagues at the University of Queensland's Diamantina Institute believe they have found out why. Once a vaccine is administered, the cancer immediately responds by mounting a counter-attack producing proteins, called cytokines, which block the effect of the treatment.

"In the animal model, we've found that if we block these cytokines so they can't do anything . . . the cancer can be controlled," Professor Frazer said. "We're encouraged that the animal studies have shown us how to overcome a problem which we've previously recognised existed (and) that we didn't know how to sort out. "This is an optimistic step in the right direction."

The scientists hope to start human trials to test their theory within a year. "We've got to show that what works in animals also works in humans and it may not," Professor Frazer said. If scientists can boost their effectiveness, vaccine therapies for cancer offer advantages over traditional ones because they have few toxic side effects. Professor Frazer talked about the latest research to the Sir Mark Oliphant Conference on Vaccine and Immunotherapy Technologies in Canberra.


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