Intensive blood pressure treatment does not affect gait speed, limit mobility in older adults

An intensive blood pressure treatment intervention did not change the gait speed or limit the mobility of adults who were 75 years old or older, according to an analysis of a randomized trial.

All of the participants had hypertension, but they had no history of type 2 diabetes or stroke.

Lead researcher Michelle C. Odden, PhD, of the School of Biological and Population Health Sciences at Oregon State University, and colleagues published their results online in JAMA Internal Medicine on Feb. 6.

The researchers examined the SPRINT trial, which found that targeting a systolic blood pressure of less than 120 mm Hg led to improvements in cardiovascular morbidity and mortality compared with a target of less than 140 mm Hg in adults who were at least 50 years old, had hypertension and did not have type 2 diabetes or stroke.

This analysis included 2,629 participants from the SPRINT trial who were at least 75 years old and were randomized to a systolic blood pressure target of less than 120 mm Hg or less than 140 mm Hg. The mean age was 79.9 years old, and 62.1 percent of the participants were men.

The researchers collected data from Nov. 8, 2010, to Dec. 1, 2015. They used the four-minute walk test to measure gait speed at the time of randomization and annually afterward. Participants self-reported their mobility at baseline and each year afterward.

Of the participants, 17.6 percent had a mobility limitation at baseline, including 17.7 percent in the intensive treatment group and 17.6 percent in the standard treatment group. Participants with a mobility limitation were older, had a higher body mass index, used more antihypertensives and were more likely to be female and not white, according to the researchers.

At baseline, the mean gait speed was 0.91 m/s, while gait speed declined 0.026 m/s on average each year. The researchers mentioned that there were no differences in mean gait speed decline between the groups, while the trajectory of gait speed of similar in participants randomized to intensive or standard treatment. They added that the change in gait speed between the groups did not differ significantly for subgroups based on age, sex, race or ethnicity, baseline systolic blood pressure, chronic kidney disease or history of cardiovascular disease.

“Several possible reasons explain why intensive treatment did not substantially affect gait speed or mobility outcomes in SPRINT participants 75 years or older or in most of the subgroups examined,” the researchers wrote. “Gait speed incorporates function across multiple domains, including cardiorespiratory fitness, musculoskeletal health, vision, balance, and even mood or psychosocial health; therefore, the cardiovascular benefit conferred from intensive [blood pressure] control might not extend to mobility outcomes owing to the multifactorial nature of mobility. The literature on heart failure presents a similar conundrum in that the optimal therapy can differ for the outcomes of survival and exercise capacity; medications that confer a survival benefit, such as beta-adrenergic blockers, can negatively affect exercise capacity. In addition, physical functioning is affected by a lifetime of exposures, so the intervention may not have been long enough to significantly affect mobility.”

Still, the study had a few limitations, according to the researchers, including that it excluded adults with a history of diabetes or stroke, symptomatic heart failure, orthostatic hypotension, dementia or an indication for specific antihypertensives. The trial also did not enroll elderly adults living in nursing homes.

In addition, the staff who assessed gait speed were not blinded to treatment assignment. Further, the researchers stopped the SPRINT trial early because the intensive treatment group had a significantly lower rate of the primary composite outcome. Thus, the researchers noted they could not determine the long-term effects of intensive blood pressure lowering on gait and mobility outcomes.