A new study has shown that walking speed in older people is predictive of cardiovascular mortality, with those in the slowest tertile three times more likely to suffer CV death over five years than those who walked faster.
Dr. Julien Dumurgier (INSERM, Paris, France) said this kind of walking test could be part of a general clinical assessment of those aged over 65.
Second author, epidemiologist Dr. Alexis Elbaz (INSERM) stated that, “We found that old persons who walk slowly have an increased risk of death, in particular cardiovascular death; it’s an easy message…. This shows us the very important role of trying to maintain good fitness in older persons,” he added.
Geriatricians Drs. Rowan H. Harwood (Queen’s Medical Center, Nottingham, UK) and Simon P. Conroy (Leicester Royal Infirmary, Leicester, UK) are the authors of an editorial accompanying the study.
Nevertheless the French group showed a strong relationship between slow walking speed and cardiovascular death. “People have looked at vascular events before and they have looked at vascular mortality, but they haven’t put it in the context of all the other sorts of mortality, and they haven’t pulled mortality apart in the way that this group did.”
In their linked prospective cohort study, Dumurgier and colleagues recruited 3,208 men and women living in the community, aged 65 or older and were followed for an average of 5.1 years.
The main outcome measures were mortality overall and according to the main cause of death, by tertiles of baseline walking speed, adjusted for several potential confounders.
Elbaz explained that walking speed was measured by asking participants to walk at their usual speed and then asking them to walk, over 6 m down a corridor, at their maximum pace without running. Although chronometers were used in this study, this measure could also be simply performed in a doctor’s office using a watch or timer, to obtain walking speed in meters per second, he noted.
During follow-up, 209 participants died (99 from cancer, 59 from cardiovascular disease, 51 from other causes); those in the lowest third of baseline walking speed had a 44% increased risk of death (hazard ratio 1.44), compared with the upper tertiles.
Analyses for specific causes of death showed that those with a low walking speed had about a threefold increased risk of cardiovascular death (HR 2.92) compared with participants who walked faster. There was no association between walking speed and cancer mortality (HR 1.03), however.
Elbaz said that assessment of walking speed is simple and can be performed easily in a routine clinical setting, “in fact, some geriatricians already do this kind of thing, following the measure over time, seeing if it remains stable, etc,” he noted.
However, he cautioned that walking speed should not be used in isolation to identify people at high risk of cardiovascular death but rather “in the context of a global assessment.” And he noted that the participants studied by his group were community-dwelling, well-functioning older people in fairly good health who were able to come by themselves to the study center. Assessment of older, frailer individuals “is more complicated,” he admitted.
Harwood said, “I would like to caution against being too simplistic. One of the things this study is telling us is how fit someone is, which is a reflection of how much exercise they do, and we know exercise is good for us.” And he says that in an observational study, “you can never completely adjust for all confounders, so residual confounding is always a problem.”
But he agrees that measuring walking speed in this way is, at least, “an objective measure of physical performance, and it’s far more accurate than asking a person how much regular exercise they do. It’s a bit like the difference between asking a person how much they eat and weighing them.”
Dumurgier J, Elbaz A, Ducimetiere P, et al. Slow walking speed and cardiovascular death in well functioning older adults: prospective cohort study. BMJ, Nov 10, 2009; DOI: 10.1136/bmj.b4460. = Harwood RH and Conroy SP. Slow walking speed in elderly people. BMJ 2009; DOI:10.1136/bmj.b4236. .