The substantial reductions in cardiovascular disease (CVD) and all-cause mortality achieved with intensive blood pressure lowering in the landmark SPRINT trial were not sustained in a newly released long-term follow-up.
The loss of the mortality benefits corresponded with a steady climb in the average systolic blood pressures (SBP) in the intensive treatment group after the trial ended. The long-term benefit serves as a call to develop better strategies for sustained SBP control.
“We were disappointed but not surprised that the blood pressure levels in the intensive goal group were not sustained,” acknowledged William C. Cushman, MD, Medical Director, department of preventive medicine, University of Tennessee Health Science Center, Memphis. “There are many trials showing no residual or legacy effect once the intervention is stopped.”
Long-term results do not weaken SPRINT
One of the coinvestigators of this most recent analysisin JAMA Cardiology and a member of the SPRINT writing committee at the time of its 2015 publication in the , Dr. Cushman pointed out that the long-term results do not weaken the main trial result. Long-term adherence was not part of the trial design.
“After the trial, we were no longer treating these participants, so it was up to them and their primary care providers to decide on blood pressure goals,” he noted in an interview. Based on the trajectory of benefit when the study was stopped, “it is possible longer intensive treatment may lead to more benefit and some long-term residual benefits.”
The senior author of this most recent analysis, Nicholas M. Pajewski, PhD, associate professor of biostatistics and data science, Wake Forest University, Winston-Salem, N.C., generally agreed. However, he pointed out that the most recent data do not rule out meaningful benefit after the study ended.
For one reason, the loss of the SBP advantage was gradual so that median SBP levels of the two groups did not meet for nearly 3 years. This likely explains why there was still an attenuation of CVD mortality for several years after the all-cause mortality benefit was lost, according to Dr. Pajewski.
“It is important to mention that we were not able to assess nonfatal cardiovascular events, so while the two groups do eventually come together, if one thinks about the distinction of healthspan versus lifespan, there was probably residual benefit in terms of delaying CVD morbidity and mortality,” Dr. Pajewski said.
In SPRINT, CVD mortality reduced 43%
In the 9,631-patient SPRINT trial, the intensive treatment group achieved a mean SBP of 121.4 mm Hg versus 136.2 mm Hg in the standard treatment group at the end of 1 year. The trial was stopped early after 3.26 years because of strength of the benefit in the intensive treatment arm. At that time, the reductions by hazard ratio were 25% (HR, 0.75; P < .001) for a composite major adverse cardiovascular event (MACE) endpoint, 43% for CVD mortality (P = .005), and 27% for all-cause mortality (P = .003).
In the new observational follow-up, mortality data were drawn from the National Death Index, and change in SBP from electronic health records in a subset of 2,944 SPRINT trial participants. Data were available and analyzed through 2020.
The newly published long-term observational analysis showed that the median SBP in the intensive treatment arm was already climbing by the end of the end of the trial. It reached 132.8 mm Hg at 5 years after randomization and then 140.4 mm Hg by 10 years.
This latter figure was essentially equivalent to the SBP among those who were initially randomized to the standard treatment arm.