WINSTON-SALEM, NC — The cardiovascular benefits of intensive blood-pressure lowering, including a striking decline in heart failure, do not result in better mobility among elderly patients at increased CV risk, a new SPRINT analysis suggests.
Among 2629 participants aged 75 years and older, there was no difference in mean gait-speed decline between those randomized to a systolic BP target of less than 120 mm Hg vs the prevailing standard of less than 140 mm Hg (mean difference 0.0004 m/s per year; P=0.88 for difference).
This lack of effect of intensive BP lowering on the change in gait speed was consistent across subgroups defined by age, sex, race, baseline systolic BP, history of chronic kidney disease, and history of cardiovascular disease.
"Obviously we were hoping that with the SPRINT results and benefit on things like heart failure, which obviously has a huge impact on function, that that might translate into some benefit in gait speed, but if you think through the numbers, there weren't that many cardiovascular events when you look at the whole cohort," senior investigator Dr Nicholas Pajewski (Wake Forest School of Medicine, Winston-Salem, NC) told heartwire from Medscape.
The study, published online February 6, 2017 in JAMA Internal Medicine, is reported to be the first large-scale randomized clinical BP trial to report on gait function. Observational studies have produced mixed results, although most suggest an association between higher BP and worse gait function in older adults.
Commenting to heartwire , Dr Harlan Krumholz (Yale University School of Medicine, New Haven, CT), who was not associated with the study, said that given the relatively small number of events in SPRINT, it would have been unexpected to see that the difference in heart failure would translate into an average benefit in physical function across the entire group.
He added, "It's reassuring that there wasn't any harm but that also means there wasn't any benefit; and we're still struggling with how best to translate the findings of this study, whether to jump in and embrace its results or be intrigued by the possibility but eager for confirmation because it represents such a dramatic change in our practice."
In the core SPRINT population of adults aged 50 years and older who were hypertensive but not diabetic, the intensive-treatment group had 27% lower risk of all-cause mortality and 43% lower risk of CV death than the standard-therapy group. These benefits were accompanied by a 38% reduction in heart-failure development.
One of the criticisms of the trial, however, is that the intensive-treatment group also had a significantly higher risk of acute kidney injury or failure, syncope, hypotension, and electrolyte imbalances.
Pajewski said, "I guess it's really not all that surprising that on the whole you have some negative risk for adverse events, you save some cardiovascular events, and functionally the groups end up being pretty similar."
He added, "The message is really that we didn't see any acceleration of the decline in gait speed with intensive treatment, and so at least we think that as this perhaps gets incorporated into the guidelines, there's not a concern that this will speed functional decline, which is a good sign."
Possible explanations for why the CV benefits didn't carry over to mobility are the multifactorial nature of mobility and that the 3-year intervention may not have been long enough, the investigators, led by Dr Michelle C Odden (Oregon State University, Corvallis), suggest.
At baseline, 17.6% of the 2629 participants (mean age 79.9 years; 62.1% male) had a mobility limitation, defined as having a gait speed of <0.6 m/s or reporting a lot of difficulty climbing stairs and reporting some difficulty walking about or being confined to a bed in response to questions on the Veterans RAND (VR) 12-item Health Survey (VR-12) and the EQ-5D questionnaire.
Intensive BP lowering appeared to be associated with a slower rate of gait-speed decline in participants with better physical quality of life, but the investigators caution that the effect size was modest and did not reach statistical significance in either group. The mean differences were 0.004 m/s for those with higher VR-12 physical-component summary scores of >40 (95% CI -0.002 to 0.010) and -0.008 m/s for those with scores <40 (95% CI -0.016 to 0.001).
Additional analyses found no effect of intensive BP lowering on transitions to a mobility limitation (hazard ratio 1.06, 95% CI 0.91–1.22) or from a mobility limitation to no mobility limitation (HR 0.92, 95% CI 0.77–1.10).
Commenting to heartwire , Dr Donna K Arnett (University of Kentucky College of Public Health, Lexington) said the study is very positive in light of the clinical concerns of putting elderly individuals on very tight BP control and the potential to cause imbalance, problems with mobility, and falls.
"That they found absolutely no difference at all between the intensive- and usual-treatment arms to me was very compelling evidence that getting these high levels of control are not harmful in terms of mobility in the elderly population," she said.
SPRINT was funded by the National Institutes of Health. Odden and Pajewski report no relevant financial relationships. Disclosures for the coauthors are listed in the paper. Krumholz and Arnett reported no financial disclosures.
Heartwire from Medscape © 2017 Medscape, LLC
Cite this: No Mobility Gain or Loss With Strict BP Control Seen in SPRINT Elderly Participants - Medscape - Feb 08, 2017.