21 July 2008 - Diagnosis and management of hypertension in people over the age of 50 years should be based on systolic blood pressure (SBP), say Bryan Williams, MD (University of Leicester, UK), and co-authors in a viewpoint article in The Lancet: “will produce adequate control of diastolic [BP] in all but a few patients, contrasting starkly with the existing emphasis on diastolic [BP], which frequently leaves those most at risk with uncontrolled systolic BP”.

They say that SBP is becoming more important as the aging population grows. SBP consistently rises with age, in contrast to diastolic BP (DBP), which rises up to around the age of 50 years and falls thereafter. Thus, the prevalence of high SBP increases over age 50 years, whereas the high diastolic BP almost disappears. As over 75% of people with high BP are over 50 years old, the burden of disease is therefore mainly due to elevated SBP.

“The use of diastolic BP for diagnosis and risk stratification in our aging populations has thus become illogical”, Williams and colleagues write. They say that trials in patients with predominantly isolated systolic hypertension have confirmed the safety and cardiovascular benefits of lowering systolic BP. “These trials have not shown that a resultant fall in diastolic BP would impart harm or offset the benefit of systolic BP reduction” they emphasize.

To simplify treatment strategies for physicians and policy makers, the editorialists say that the clinical focus should be redirected exclusively onto SBP in people aged over 50 years for four reasons. First, SBP is more easily and accurately measured than DBP, and is a better predictor of cardiovascular risk. “Indeed, diastolic pressures are often normal or low in the highest risk patients” the authors note. Second, this approach would clear up patients' confusion over the concept of hypertension defined by two different numbers, and which number is more important. And a third reason is that physicians too have been confused by conflicting messages about the relative importance of diastolic and SBP, with many still using DBP to guide treatment decisions.

Lastly, Williams and co-workers say, focusing public-health messages on a single number for the over 50s could “dramatically improve the treatment and control of systolic BP and further reduce the associated cardiovascular morbidity and mortality”.

The authors acknowledge that a continued emphasis on both systolic and DBP will be required for hypertensive patients under 50 years, as up to 40% of those under 40 years, and one-third of those aged between 40 and 50 years, have isolated diastolic hypertension. But they say this should not “dilute” the message regarding the overwhelming importance of systolic BP for most hypertensive patients.

They conclude: “Such an initiative would have major public health implications for the prevention of BP-related cardiovascular disease”.

Lancet 2008; Advance online publication