No Need to Force Blood Pressure below 140/90?

The purpose of treating high blood pressure is to reduce it enough to prevent mortality or morbidity (by which we mean disease or illness). So a new review is of interest to those taking anti-hypertensive medications, especially if they have annoying or distressing side effects. The Cochrane Database of Systemic Reviews contains a report of an analysis of outcomes in 7 important clinical trials covering 22,000 patients being treated for hypertension.

While standard practice for some years has been to target 140/90 mm Hg as the blood pressure levels to be achieved with treatment, newer guidelines have recommended targets below these levels. The principal has been “as low as possible”. The purpose of the Cochrane Review was to determine if lower blood pressure targets (i.e. 135/85 mm Hg or lower) were rewarded by a reduction in mortality and morbidity, compared with achieved levels of lower than 140-160/90-100 mm Hg.

After searching all likely publication sources, the analysts couldn’t find any suitable studies that reported different systolic blood pressure results adequately. But they found 7 trials, containing 22,089 patients, reporting diastolic pressures. They found no evidence that reaching a target of below 90 mm Hg diastolic blood pressure provided any benefit with respect to reduced mortality or morbidity (heart attack, stroke, congestive heart failure, major cardiovascular events, or end-stage renal disease). This absence of a benefit in reducing diastolic pressures below 90 mg Hg suggests that many people can avoid having to increase their dose or add another antihypertensive drug, just to get down to lower target blood pressure levels.

As we might have expected, all experts say “more trials are needed”. There are no good studies comparing 130/80 patients with 115/70 patients; indeed, such a study would be very hard to do, require many thousands of patients, and probably show no difference. In the meantime, doctors can concentrate on treating the individual patient - balancing the reduction in blood pressure achieved against the cost of side effects produced.