Effects of Intensive Blood Pressure Lowering Therapy on Gait and Mobility

Intensive blood pressure (BP)-lowering therapy was not linked to changes in either gait speed or mobility status transition in adults aged 75 years or older, according to research published in JAMA Internal Medicine.

Nicholas M. Pajewski, PhD, from the Division of Public Health Sciences, Department of Biostatistical Sciences, Wake Forest School of Medicine in Winston-Salem, North Carolina, and colleagues conducted a randomized clinical trial (Systolic Blood Pressure Intervention Trial [SPRINT]; ClinicalTrials.gov identifier: NCT01206062) of participants with hypertension (n=2636) to examine the effect of intensive BP control on patients’ gait and mobility.

Study participants were randomly assigned to receive either intensive treatment (systolic BP [SBP] <120 mm Hg; n=1317) or standard treatment (BP <140 mm Hg; n=1319). Baseline demographic, clinical, and laboratory data were collected for all participants. The researchers measured gait speed at the time of randomization, and self-reported mobility was gathered using quality-of-life instruments. Both measures were collected at baseline, and annually thereafter.

Mean age of study participants was 79.9 years, and they were followed up for a mean of 2 years (interquartile range [IQR], 2-3 years). At baseline, 17.6% of participants were classified as having a mobility limitation, with similar percentages identified in the intensive treatment and standard treatment groups (17.7% and 17.6%, respectively). Those who were identified as having a mobility limitation were older and were more likely to be female and nonwhite, as well as to have a higher body mass index.

Mean gait speed at baseline was 0.91 m/s, with a mean annual change of −0.026 m/s (95% CI, −0.028 to −0.023). In both the intensive and standard treatment groups, trajectory of gait speed was similar among participants (mean difference, 0.0004 m/s per year; 95% CI, −0.005 to 0.005 m/s per year; P =.88 for difference). Change in gait speed did not differ significantly when stratified by age, sex, race, ethnicity, baseline SBP, chronic kidney disease, or history of cardiovascular disease.

Mean transition rate from no mobility limitation to mobility limitation was 12.5 per 100 person-years, with no effect of intensive treatment identified (hazard ratio [HR], 1.06; 95% CI, 0.91-1.22). In addition, no effect was identified on transitions from mobility limitation to no mobility limitation (HR, 0.92; 95% CI, 0.77-1.10), although participants in the intensive treatment group with no mobility limitation had a lower risk for death than those in the standard treatment group (HR, 0.62; 95% CI, 0.43-0.90).

“Several possible reasons explain why intensive treatment did not substantially affect gait speed or mobility outcomes in SPRINT participants…in most of the subgroups examined,” the researchers wrote, explaining that because gait speed incorporates function across multiple domains, the cardiovascular benefit “conferred from intensive BP control might not extend to mobility outcomes owing to the multifactorial nature of mobility.”

“The benefits of intensive BP lowering on cardiovascular prevention and mortality do not appear to affect short-term mobility,” the researchers concluded.

Study Limitations

• SPRINT excluded those with a history of diabetes or stroke, symptomatic heart failure, or an indication for specific antihypertensive agents, meaning results may not be applicable to these populations.
• Elderly persons living in nursing homes were also excluded.
• Results do not address the effect of initiating BP therapy.
• Clinic staff who performed the gait speed assessments were not blinded to treatment assignment.
• SPRINT was stopped early because of “a significantly lower rate of primary composite outcome in the intensive-treatment group,” meaning long-term effects cannot be examined.

Disclosures: Dr Peralta reports serving as a consultant for Cricket Health, Inc. and Vial Labs, Inc.

Reference

Odden MC, Peralta CA, Berlowitz DR, et al; for the Systolic Blood Pressure Intervention Trial (SPRINT) Research Group. Effect of intensive blood pressure control on gait speed and mobility limitation in adults 75 years or older [published online February 6, 2017]. JAMA Intern Med. doi: 10.1001/jamainternmed.2016.9104