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Treating mild high blood pressure with drugs found to be ineffective

Posted Aug 17 2012 1:51pm

Back in June I dedicated a post to the effectiveness of blood pressure medication. It was triggered by the fact that there’s abundant data to suggest that cholesterol-lowering ‘statin’ medication is really very ineffective. And by that I mean that the vast majority of people who take statins will not benefit. I wondered whether the same might be true for blood pressure medication, and it turns out it is.

As a general rule, medical intervention tends to be most effective in people who are ‘sickest’ or at greatest risk of disease. So, logic dictates blood pressure medication will work best in people with the highest blood pressures to begin with. But what about people who have high blood pressure (hypertension) that is only ‘mild’ in nature?

Researchers from the generally respected collective known as the ‘Cochrane Collaboration’ have just published a review [1] of the relevant evidence here. They looked at data from studies in which people with systolic blood pressures (the higher blood pressure reading) of 140-159 mmHg and/or diastolic blood pressures (the lower reading) of 90-99 mmHg. Individuals in these trials had no prior history of cardiovascular disease (e.g. previous heart attack or stroke). Four studies which included about 9,000 patients in total were analysed. Average length of treatment was between 4 and 5 years. So, lots of people, and a decent duration of treatment too.

Results showed that in those treated with active medication (compared to placebo) were:

  • At no reduced risk of developing heart disease
  • At no reduced risk of stroke
  • At no reduced risk of ‘total cardiovascular events’ (essentially heart attacks and strokes combined)
  • At no reduced risk of overall risk of death

Here’s the authors’ conclusions:

Antihypertensive drugs used in the treatment of adults (primary prevention) with mild hypertension (systolic BP 140-159 mmHg and/or diastolic BP 90-99 mmHg) have not been shown to reduce mortality or morbidity [disease] in RCTs [randomised controlled trials].

Today’s British Medical Journal includes a news item about this study [2]. Here’s a quote from it:

James Wright, coordinating editor of the Cochrane Hypertension Group, told the BMJ that until now it has simply been assumed that treating mild hypertension, which is what most hypertensive patients have, is beneficial. He said that doctors and guideline writers have based their opinions on a combination of assumptions and data from clinical trials in which patients with mild hypertension were not analysed separately.

That comment regarding the assumption doctors have made here, struck a chord. It reckon there’s much we doctors do that we assume to be beneficial. Worse still, I think we’ll often call what we do ‘evidence-based’ even when we don’t have good evidence for it. As I remarked to a journalist yesterday, it’s one thing calling something evidence-based, and another something actually being based on good evidence.

Another quote in the BMJ piece comes from Professor Jerome Hoffman of UCLA and an expert in critical appraisal of medical literature. He said:

We’ve long known that almost all benefit from treating severe hypertension comes with lowering BP [blood pressure] just a little. On the other hand, efforts to lower BP to ‘normal,’ typically requiring multiple drugs, are not only usually unsuccessful but produce more harm than good, since adverse effects of intensive treatment outweigh the minimal marginal benefit of a little more BP ‘control.’ Drug treatment of mild hypertension….may be of great value to drug makers, but it was almost predictable that it would provide little or no benefit for patients.

David Cundiff, one of the authors of the Cochrane review has said that he “believes that the analysis should lead to dramatic changes in the way doctors treat mild hypertension, allowing patients to throw away their blood pressure pills and focus instead on far more effective as well as evidence based approaches…”

Dr Des Spence, a general practitioner and BMJ columnist is not so sure though. He’s quoted as saying:

Risk is abstract, and doctors and patients struggle with the concept and may not follow the guidelines. Doctors see a blood pressure of 156/98 and they prescribe. It’s easier to treat than not treat—you never get blamed for overtreating.

I’m broadly with Dr Spence on this. I’d be (pleasantly) surprised if doctors on the whole took this evidence on the chin and made meaningful changes to the way they manage mild hypertension. After all, a lot of what we doctors do is not evidence-based, so why start now?

References:

1. Diao D, Wright JM, Cundiff DK, Gueyffier F. Pharmacotherapy for mild hypertension. Cochrane Database Syst Rev2012;(8):CD006742

2. Lenzer J. Cochrane review finds no proved benefit in drug treatment for patients with mild hypertension. BMJ 2012;345:e5511

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