Benefits Of Lowering High Blood Pressure Not Proven
High blood pressure is risky. However, the new analysis says that the lower blood pressure benefits are not proven either.
A systematic review of databases submitted to the Cochrane review shows that lowering blood pressure below 140/90 has no proven benefits. Recent focus has been on maintaining lower blood pressure readings than in the past – as low as 115/70 - to reduce risk of heart disease, stroke, and reduce mortality. The review comes from Dr Jose Agustin Arguedas (Universidad de Costa Rica, San Pedro de Montes de Oca) and colleagues, who say that a five year trend to lower blood pressure readings “is not proven”.
Dr. Arguedas, in an interview with heartwire, said, "We found there is no evidence that reaching a target of below 90 mm Hg diastolic BP will provide additional clinical benefit, but we can't say whether lowering systolic BP below 140 mm Hg will be beneficial or not; there are no data."
The research included 22 000 subjects that compared blood pressure readings and stroke, heart failure, kidney disease and heart attack. The study concluded that lowering blood pressure too much with drugs may even be risky.
The researchers say "the most obvious is the need for large doses and increased number of antihypertensive drugs. This has inconvenience and economic costs to patients. More drugs and higher doses will also increase adverse drug effects, which if serious could negate any potential benefit associated with lower BP”. Lower blood pressure is not without consequences, and can cause adverse cardiovascular events in some patients.
Patients with high blood pressure are still are risk. But the question is whether bringing blood pressure levels lower with medications is beneficial. There is no debate that naturally lower blood pressure readings reduce the risk of heart attack, stroke, kidney disease, and congestive heart failure.
According to Dr Franz Messerli from St Luke Roosevelt Hospital, New York …”the benefits of antihypertensive medications are most obvious in patients with the highest BP. The closer we get to 'normotension,' the more difficult it becomes to show benefits of (blood pressure) lowering. Dr. Messerli was not involved in the study.
A study of one million patients, the Lewington meta-analysis, clearly showed reduced risk of cardiovascular events in “people whose' usual' BP is 115/70 mm Hg compared with those with a 'usual' BP of 130/80. However there are no data and probably never will be that lowering BP from 130/80 mm Hg to 115/70 mm Hg confers any benefits”, adds Dr. Messerli.
An ongoing study, the Action to Control Cardiovascular Disease in Diabetes (ACCORD) study is looking at the relationship between systolic blood pressure and stroke and heart attack, over a four to eight year period among individuals with a first non-fatal heart attack or stroke.
Questions remain about the benefits of lowering blood pressure in patients at high risk who have kidney disease or diabetes. The benefit of blood pressure targets of 130/80 in high risk patients was not evident, but was “less robust”. More studies are needed to determine whether lowering systolic blood pressure among high risk patients shows benefit.
Arguedas JA, Perez MI, Wright JM. Treatment blood pressure targets for hypertension. Cochrane Database Syst Rev 2009; 3:CD004349.