Intensive treatment to reduce systolic blood pressure to less than 120mmHg is associated with an increased reduction in cardiovascular events and death, compared to the standard National Institute for Health and Care Excellence (NICE) treatment target of 140mmHg or below, updated findings from a major study have suggested.
However, some serious adverse events — such as hypotension and acute kidney injury — were more common in the intensive treatment group.
The Systolic Blood Pressure Intervention Trial (SPRINT) is a randomised controlled clinical trial designed to determine whether a systolic blood pressure target of less than 120mmHg (intensive treatment) is associated with a lower rate of clinical events than a systolic blood-pressure target of less than 140mmHg (standard treatment).
The primary results of the trial, which began in 2009, were reported in 2015 but the trial continued to collect data during an observational post-intervention period ending in July 2016.
More than 9,000 participants aged at least 50 years, who were at increased risk for cardiovascular disease but did not have diabetes or previous stroke, were randomised to either the intensive treatment target or the standard treatment target.
At a median of 3.33 years of follow-up, the rate of the primary outcome during the trial was significantly lower in the intensive treatment group than in the standard treatment group (1.77% per year vs 2.40% per year; hazard ratio [HR] 0.73; 95% confidence interval [CI], 0.63 to 0.86). All-cause mortality was also significantly lower in the intensive treatment group (1.06% per year vs. 1.41% per year; hazard ratio, 0.75; 95% CI, 0.61 to 0.92).
However, serious adverse events of hypotension, electrolyte abnormalities, acute kidney injury or failure, and syncope were significantly more frequent in the intensive treatment group.
Cora Lewis, professor and chair of the Department of Epidemiology in the University of Alabama at Birmingham School of Public Health, and primary investigator of the study, said: “One criticism of the original SPRINT findings was that, of the components of the primary outcome, only heart failure and death due to CVD [cardiovascular disease] were significantly lower in the intensively treated group.
“The final results found that risk of heart attack, along with heart failure and death from CVD, was significantly lower in the group treated to less than 120[mmHg], and the risk of the primary outcome excluding heart failure was still significantly lower in the more intensively treated group.”
Paul Wright, lead cardiac pharmacist at Barts Health NHS Trust, said the method of measuring blood pressure within the trial could have led to lower readings compared to other trials of antihypertensive agents, which may have meant that clinic-measured systolic readings in the trial were closer to 140mmHg in the intensive group.
“Blood pressure targets are hotly debated, with international guidelines differing in the levels chosen and also varying from a ‘one-size-fits-all’ to other approaches that are more tailored to patients’ comorbidities and characteristics,” he added.
“Lowered blood pressure targets may be advantageous in a select cohort of patients but, given the off-set of increased side effects … it is unlikely to be widely adopted in UK practice.”