Raised blood pressure is believed to be a risk factor for cardiovascular diseases such as heart disease and stroke. Studies show that, in a population, the higher the blood pressure, the greater the risk of cardiovascular disease. This has led to some researchers suggesting that the lower the blood pressure is, the better.
However, we have seen examples in the past where this ‘lower is better’ concept seems misguided. For example, we know that low levels of cholesterol are associated with an increased risk of death, principally because of an association with an increased risk of cancer. See here for more about this. There is also evidence that more intensive pharmacological lowering of blood sugar levels in diabetics speeds their demise. See here for more about this. It really does seem that when it comes to markers of disease, lower is not necessarily better.
So, what about blood pressure? It’s important to bear in mind, I think, that blood pressure is what forces blood into tissues to feed and oxygenate them. Very low blood pressure can kill. However, is it not possible that at a certain blood pressure life can go on, but the quality of that life is somewhat impaired? This is certainly what I and some other practitioners see in practice. I can tell you from experience that there seems to be very few individuals wandering around with a blood pressure of 90/60 who feel bursting with vitality and energy. And when measures are taken to help restore blood pressure to higher levels, these individuals usually feel much better.
The other thing to bear in mind is that even though studies may show an association between lower blood pressure and reduced risk of cardiovascular disease, that does not necessarily mean that more intensive drug treatment to lower blood pressure will lead to better outcomes (just look at the diabetes example above).
This issue was the focus of a recent review published by researchers from the so-called Cochrane Collaboration. In this review, researchers amassed data from 7 trials and a total of 22,000 patients who had been treated with medication for high blood pressure . A commonly aimed-for target for blood pressure is 140/90. What the researchers did was compare individuals who had had their blood pressures lowered to 140-160/90-100 with those who had had theirs lowered to less than or equal to 135/85. What they were essentially asking is whether lowering blood pressure to lower than the common target of 140/90 led to improvements in outcome.
Compared with those with higher blood pressures, those who had their blood pressure lowered to 135/85 or less saw:
NO reduced risk of heart attack
NO reduced risk of stroke
NO reduced risk of heart failure
NO reduced risk of kidney failure (end-stage renal disease)
NO reduced risk of overall risk of death
In other words, there were no benefits from more intensive blood pressure lowering with medication. The authors concluded: ‘there is no evidence to support aiming for a blood pressure target lower than 140/90 mmHg in any hypertensive patient.’ As we’ve seen before, lower is not necessarily better.
1. Arguedas JA, et al. Treatment blood pressure targets for hypertension. Cochrane Database of Systematic Reviews 2009, Issue 3, Article Number: CD004349.