Measure and diagnosis of hypertension should focus exclusively on systolic blood pressure in patients aged over 50 years, rather than using both systolic and diastolic as is current practice, according to a Viewpoint published online June 18 in The Lancet. The proposal was put forth by Bryan Williams, University of Leicester and Leicester Royal Infirmary, Leicester, United Kingdom.
The experts say that, because of ageing populations, systolic hypertension (SH) is becoming much more common and important due to its high prevalence in patients aged 50 years and over, compared with diastolic hypertension (DH).
Systolic blood pressure (SBP) rises with age, but diastolic blood pressure (DBP) only rises until around age 50 and falls thereafter, at a time when risk of cardiovascular disease begins to rise. Thus there is an increased prevalence of SH in patients aged 50 years and over, and an almost total disappearance of DH.
"Since more than 75% of people with hypertension are aged over 50 years, the burden of disease is mainly due to systolic pressure. The use of diastolic pressure for diagnosis and risk analysis in our ageing populations has thus become illogical," the authors say.
In order to simplify treatment strategies for physicians and policy makers, as well as to better focus the minds of drug innovators on the correct targets, the authors propose that, in patients aged 50 years and over, only SBP needs to be measured, for 4 reasons.
First, SBP is more easily and accurately measured than DBP and is a better predictor of risk. Second, information with 1 number would be more understandable for patients who are often confused about which of the 2 numbers is of greater significance. Third, doctors themselves have received many conflicting messages about SBP and DBP, and many still use DBP to guide treatment decisions; this proposal would simplify things for them. Fourth, focusing a public-health campaign on a single number for people aged 50 years and over has the potential to dramatically improve treatment outcomes for those with SH and reduce the associated disease and death rates.
The risk of cardiovascular disease rises continuously as SBP increases from 115 mm Hg. Most international and national guidelines advocate a target of below 140 mm Hg, but there is a lack of evidence from prospective randomized clinical trials to define the best target for SBP treatment. The authors say that "such trials are much needed and perhaps our call for a renewed focus on SBP will provide a catalyst for them to be designed."
The authors acknowledged that for patients aged less than 50 years, the scenario is different.
Up to 40% of patients aged less than 40 years have isolated DH, while this figure is around a third in patients aged 40 to 50 years. Thus for these patients, a continued emphasis on both SBP and DBP is appropriate.
"However, this much smaller group of patients should not dilute the key message regarding the overwhelming importance of systolic blood pressure for most patients with hypertension," the authors wrote. They add that focusing on SBP in these younger patients will almost always result in adequate control of DBP; yet if DBP is the sole target, many patients most at risk will be left with uncontrolled SPB.
"We believe that systolic blood pressure should become the sole defining feature of hypertension and key treatment target for people over age 50 years … [this] will simplify the message for practitioners and for patients, will improve awareness and understanding of treatment objectives, and will ultimately lead to more effective treatment of high blood pressure," the authors added. "Such an initiative would have major public-health implications for the prevention of blood-pressure related cardiovascular disease."
The Lancet, June 26, 2008
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