LOS ANGELES • High blood pressure was redefined on Monday by the American Heart Association (AHA), which said the disease should be treated sooner, when it reaches 130/80mm Hg, and not the previous limit of 140/90.
Doctors now recognise that complications "can occur at those lower numbers", said the first update to comprehensive US guidelines on blood pressure detection and treatment since 2003.
A diagnosis of the new high blood pressure does not necessarily mean a person needs to take medication, but that "it's a yellow light that you need to be lowering your blood pressure, mainly with non-drug approaches", said Dr Paul Whelton, lead author of the guidelines published in the AHA journal, Hypertension, and the Journal of the American College of Cardiology.
Healthy lifestyle changes include losing weight, exercising more, eating healthier, not smoking, avoiding alcohol and salt, and reducing stress.
The new standard means nearly half (46 per cent) of the US population will be defined as having high blood pressure. Previously, one in three (32 per cent) had the condition, which is the second leading cause of preventable heart disease and stroke, after cigarette smoking.
The normal limit for blood pressure is considered 120 for systolic, or how much pressure the blood places on the artery walls when the heart beats, and 80 for diastolic, which is measured between beats.
Once a person reaches 130/80, "you've already doubled your risk of cardiovascular complications compared to those with a normal level of blood pressure", said Dr Whelton.
"We want to be straight with people - if you already have a doubling of risk, you need to know about it."
The new guidelines are expected to lead to a surge of people in their 40s with high blood pressure - once considered a disorder mainly among people aged 50 and older.
"The prevalence of high blood pressure is expected to triple among men under age 45, and double among women under 45," according to the report.
Damage to blood vessels is already beginning once blood pressure reaches 130/80, said the guidelines, which were based in part on a major US government-funded study of over 9,000 people nationwide.
The category of prehypertension, referring to those with systolic pressure of 120-139, no longer exists. The report said: "People with those readings now will be categorised as having either elevated (120-129 and less than 80) or stage 1 hypertension (130-139 or 80-89)."
Medication is recommended for people with stage 1 hypertension only "if a patient has already had a cardiovascular event such as a heart attack or stroke, or is at high risk of heart attack or stroke based on age, the presence of diabetes mellitus, chronic kidney disease or calculation of atherosclerotic risk".
The proper technique must be used to measure blood pressure, and levels "should be based on an average of two to three readings on at least two different occasions", according to the new guidelines.
Dr Satjit Bhusri, a cardiologist at Lenox Hill Hospital in New York, said he agrees with the change "because it allows for early lifestyle changes to be addressed".
He added: "It is important, however, to realise that the change in the definition does not give course to increased prescriptions of medications. Rather, it brings to light the need to make lifestyle changes."