Evidence for lower BP targets in doubt

ADVICE to lower blood pressure to levels below standard targets is not supported by evidence and may even be harmful to patients.

The latest Cochrane Review update has found the trend favouring a ‘lower is better’ approach did not prolong survival or lead to reductions in stroke, myocardial infarction, heart failure or renal failure.

Australian experts said the findings underscored the importance of shifting away from a focus on defined targets and individual parameters toward treatment decisions based on a patient’s overall cardiovascular risk profile.

Cochrane reviewers considered seven randomised trials comparing the impact of lower blood pressure targets (≤135/85 mmHg) with standard blood pressure targets (≤140/90 mmHg) in 22,000 adults with hypertension.

“This trend is based on the assumption that the use of drugs to bring blood pressure lower than 140/90 mmHg will reduce heart attack and stroke,” the reviewers said.

“However, this approach is not proven.”

Associate Professor Annemarie Hennessy, from the Heart Research Institute at the University of Sydney, said: “The benefits are not discernible in the 15,000 or so patients included in this analysis [including] patients with kidney disease and diabetes who are high-risk groups.

“Achieving these very lower blood pressure targets is very difficult and more side-effects can be expected when we try harder,” she said.

However, Professor Bruce Neal, senior director of the George Institute in Sydney, said a shift had occurred over the past decade in Australia and internationally away from blood pressure targets to absolute risk assessment.

“[This looks at] the risk of having a blood pressure-related event, which is not driven primarily by their blood pressure level, but driven by the combination of how old they are, if they have diabetes, do they smoke etc,” he said.

He cautioned that the exact importance of BP levels within this equation was not yet determined.

Professor Neal said the review conflicted with the findings from observational epidemiological studies in high-risk non-hypertensive individuals. These studies showed clear benefits from reducing blood pressure below recommended levels, he added.

Cochrane Database Syst Rev, 2009, Issue 3

Cochrane review on thiazides for hypertension, click here

More Cochrane review coverage, click here