Introduction:
The association between high blood pressure (BP) and risk of death varies by age and appears to be attenuated in some elderly adults. Walking speed is an excellent measure of functional status and may identify which elders may be most at risk for the adverse consequences of hypertension. Hypothesis: We hypothesized that elevated BP would be associated with greater risk of mortality in faster walkers, but not in slower walkers.
Methods:
The study population included 2,340 persons ≥ 65 years, with measured BP, in the National Health and Nutrition Examination Survey (NHANES) waves 1999-2000 and 2001-2002. Mortality data was linked to death certificate data in the National Death Index. Walking speed was measured over a 20-foot walk; 243 (8%) did not complete the walk for various safety and logistical reasons. Participants with walking speed above the mean (2.7 ft/sec) were classified as faster walkers. Potential confouders included age, sex, race, survey year, lifestyle and physiologic factors, chronic health conditions, and antihypertensive use.
Results:
There were 589 deaths recorded through December 31
st
, 2006. Among faster walkers, those with elevated systolic BP (≥140 mmHg) had a higher mortality rate compared to those with systolic BP <140 mmHg (236 vs. 161 per 100,000 person-years). Among slower walkers, mortality rates did not appear to differ by the presence of elevated systolic BP (586 vs. 563 per 100,000 person-years). This pattern remained after multivariable adjustment; there was an association between elevated systolic BP and mortality in faster, but not slower walkers (Table). Elevated diastolic BP was not independently associated with an increased risk of mortality.
Conclusions:
If confirmed in other studies, walking speed could be a simple measure to identify elderly adults who are most at risk for poor outcomes related to high blood pressure.
Table
Association of elevated blood pressure and mortality, stratified by walking speed
Hazard Ratio (HR) of Death
Faster Walking Speed >2.7 ft/sec (n = 1,279)
Slower Walking Speed ≤ 2.7 ft/sec (n = 818)
p-value for interaction
HR (95% CI)
p-value
HR (95% CI)
p-value
Elevated Systolic BP (≥140 mmHg)
1.44 (1.04, 1.99)
0.03
1.08 (0.82, 1.42)
0.56
0.11
Elevated Diastolic BP (≥90 mmHg)
1.09 (0.52, 2.27)
0.82
0.65 (0.30, 1.45)
0.28
0.28
Funding (This research has received full or partial funding support from the American Heart Association, Western States Affiliate (California, Nevada&Utah))
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