The results include data on some outcome events from the trial that had yet to be adjudicated when the primary analysis was released in 2015, as well as posttrial observational follow-up data collected through July 2016.
The data confirm and enhance the earlier findings and show that “lower is better” when it comes to blood pressure, primary investigator Cora E. Lewis, MD, professor and chair, department of epidemiology, University of Alabama at Birmingham, said in an interview.
Final results of the Systolic Blood Pressure Intervention Trial (SPRINT) were published in the May 20 issue of the New England Journal of Medicine.
For the trial, researchers enrolled 9,361 adults 50 years and older with a SBP between 130 and 180 mm Hg who were at increased risk for cardiovascular disease (CVD) but did not have a history of diabetes or stroke. Patients were randomly assigned to an intensive treatment target (SBP < 120 mm Hg) or a standard treatment target (SBP < 140 mm Hg).
In the final analysis, the rate of the primary outcome was 1.77% per year in the intensive-treatment group and 2.40% per year in the standard-treatment group (hazard ratio [HR], 0.73; 95% confidence interval [CR], 0.63-0.86; P < .001), similar to the earlier SPRINT findings.
All-cause mortality was 1.06% per year in the intensive-treatment group and 1.41% per year in the standard-treatment group (HR, 0.75; 95% CI, 0.61-0.92; P = .006), again similar to the previous findings.
“These results were highly statistically significant. It is remarkable in a trial powered for a composite CVD outcome to obtain a significant benefit for total mortality,” Dr. Lewis said.
She noted that one criticism of the initial SPRINT results was that, for the components of the primary outcome, only heart failure and death due to CVD were significantly lower in the intensively treated group.
“Heart failure can be difficult to diagnose from records in a clinical trial, and the critiques were that this was shaky evidence, given that more participants treated to less than 120 were on diuretics, which could decrease swelling, a key symptom of heart failure,” she explained.
“In these final results, SPRINT found that risk of myocardial infarction, heart failure, and death from CVD were significantly lower in the group treated to less than 120, and risk of the primary outcome, excluding heart failure, was still significantly lower in the more intensively treated group,” she noted.
After the trial phase ended, blood pressure treatment was returned to the participants’ usual source of medical care and the trial treatment goals were no longer pursued. SPRINT continued to collect data on the outcomes through July 2016. During this time, SBP rose 6.9 mm Hg in the intensive-treatment group and 2.6 mm Hg in the standard-treatment group.
“Putting all the data together from the trial phase and the phase after randomized interventions had been stopped, there was still a significant benefit for the more intensive treatment on the primary outcome and on death from all causes,” Dr. Lewis said.
In addition, a separate new analysis based on all the data showed significantly fewer first and recurrent primary outcome events with intensive treatment than with standard treatment (435 vs. 552; HR, 0.78; 95% CI, 0.69-0.89; P < .001).