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Walking Speed and Mortality Risk in Elderly with Elevated BP

Authors

Tori Socha

One of the most prevalent health problems in the United States is hypertension, and the incidence of the condition is increasing. The increase in the number of Americans with hypertension is attributed, in part, to the increase of blood pressure (BP) occurring with age coupled with the increase in the number of Americans ³65 years of age.

According to researchers, data on efforts to control BP in elderly adults is limited and recommendations for treatment do not vary between older and younger adults. Guidelines from the Joint National Committee (JNC) suggest that “therapy should not be withheld on the basis of age” and JNC-recommended BP targets do not differ by age.

Data regarding optimal BP goals for the very old (³80 years of age) are particularly limited. The HYVET (Hypertension in the Very Elderly Trial) found a positive effect of antihypertensive therapy in adults ³80 years of age on stroke, cardiovascular events, heart failure, and death based on a BP goal of <150.80 mm Hg. Noting that the participants in the HYVET were healthier than average and had lower prevalence of comorbid conditions, researchers commented that it remains unclear whether current BP targets are appropriate for the very elderly. It is also not known how to identify elderly persons who may benefit from lower BP goals.

To test their hypothesis that age may be an inadequate measure of the factors that determine the importance of BP control, the researchers recently conducted a study to examine whether the relationship between elevated BP and mortality varies by measuring walking speed among a nationally representative sample of elderly adults. They reported results of the study online in Archives of Internal Medicine [doi:10.1001/archinternmed.2012.2555].

The researchers utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted by the National Center for Health Statistics, a division of the Centers for Disease Control and Prevention. The study included data from survey participants ³65 years of age in 2 waves of the survey: 1999-2000 and 2001-2002. Mortality data were linked to death certificates in the National Death Index.

The NHANES data included information on 2340 persons ³65 years of age. Walking speed was measured over a 20-foot (6 m) walk and was classified as faster (³0.8m/s [n=1307]), slower (n=790), or incomplete (n=243).

Faster walkers were younger, less often female and black, and more likely to have a high school education compared with slower walkers. They were more likely to smoke, have a lower body mass index, and have better kidney function. They were less likely to be using antihypertension medications compared with slower walkers and have a lower prevalence of diabetes, stroke, and heart failure.

There were 589 deaths among the participants through December 31, 2006. Faster-walking participants with elevated systolic BP (³140 mm Hg) had a higher mortality rate compared with those with a systolic BP <140 mm Hg; however, slower walkers with elevated systolic BP did not appear to have increased mortality.

The adjusted association between elevated systolic BP and mortality varied across walking speed (P value for interaction, .001). Higher systolic BP was associated with a 35% elevated risk in faster walkers; the elevated risk remained even after adjustment for confounders (P=.03).

Faster walkers with elevated diastolic BP did not have a higher mortality rate compared with those without elevated diastolic BP. Among slower walkers, neither elevated systolic or diastolic BP (³90 mm Hg) was associated with mortality.

In conclusion, the researchers said, “Walking speed could be a simple measure to identify elderly adults who are most at risk for adverse outcomes related to high BP.”

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