Self-reported walking speed: a useful marker of physical performance among community-dwelling older people?

L Westbury1, HE Syddall1, C Cooper1, A Aihie Sayer1,2

1 MRC Lifecourse Epidemiology Unit2 Academic Geriatric Medicine, University of Southampton of Southampton

• Slow measured walking speed among older people is a risk factor for disability, cognitive decline and mortality and a key component of the definitions for frailty and sarcopenia.

• Guralnik first used measured walking speed in 1994 as part of a physical performance assessment.

• Direct measurement of walking speed in epidemiological studies has become common.

Guralnik et al., 1994.,A short physical performance battery assessing lower extremity function: association with self-reported disability and prediction of mortality and nursing home admission. J Gerontol, 49

Background

• Measurement of walking speed requires:– trained observers– strict measurement protocol– face-to-face contact with participants– physically able participants– space to set up a walking course

• Self-reported walking speed could be a useful alternative.

Background

• To investigate whether self-reported walking speed is associated with measured walking speed

• To investigate whether self-reported and measured walking speed are similarly associated with various clinical characteristics and mortality

Objectives

• We used data from 730 men and 999 women who participated in the Hertfordshire Cohort Study (HCS).

• Walking speed at customary pace was measured over 3 metres.

• Self reported walking speed was obtained by asking participants to rate their walking speed as:– unable to walk – very slow– stroll at an easy pace– normal speed– fairly brisk– fast

Methods

Methods

• Cross-sectional associations between clinical characteristics and self-reported and measured walking speed at baseline were examined.

• Clinical characteristics included:

– Hypertension

– Ischaemic heart disease

– Fracture history

– Diabetes

– Bronchitis

– Poor physical function

– Number of systems medicated

Methods

• Longitudinal associations between self-reported and measured walking speed and mortality outcome were examined.

• This analysis adjusted for:

– Age

– Height

– Weight

– Age left education

– Smoking history

– Alcohol consumption

Mean (SD) Men (n=730) Women (n=999)

Age (yrs) 67.0 (2.6) 67.1 (2.6)

Walking speed (self-reported)+:

Very slow 28 (3.8%) 50 (5.0%)

Stroll 173 (23.7%) 201 (20.1%)

Normal 287 (39.3%) 469 (46.9%)

Brisk 213 (29.2%) 226 (22.6%)

Fast 29 (4.0%) 53 (5.3%)

Measured walking speed (m/s) 0.95 (0.14) 0.92 (0.15)

SD:standard deviation; m/s:metres per second; +n(%)

Results: participant characteristics

Results: measured walking speed according to self reported walking speed

P<0.001 (Men)P<0.001 (Women)

0.6

0.7

0.8

0.9

1.0

Me

as

ure

d w

alk

ing

sp

ee

d (

m/s

)

Very s low Stroll Normal Fairly brisk Fas t

Self-reported walking speed

Men WomenMeans and 95% CIs are given

Results: associations with clinical characteristics

Clinical characteristic

Men Women

MeasuredSelf

reportedMeasured

Self reported

Hypertension ✓ ✓ ✓ ✓

Ischaemic heart disease ✗ ✓ ✓ ✓Fracture history ✗ ✗ ✗ ✗Diabetes ✓ ✓ ✗ ✓Physical function ✓ ✓ ✓ ✓Bronchitis ✗ ✓ ✗ ✗Number of systems medicated ✓ ✓ ✓ ✓

Results: 10 year mortality according to walking speed

HR*:1.34 (1.08,1.65), P=0.0070.750.800.850.900.951.00

Pro

porti

on

0 2 4 6 8 10Survival time (years)

Men

HR*:1 .44 (1 .11,1 .87), P=0.0050.750.800.850.900.951.00

Pro

po

rtio

n

0 2 4 6 8 10Survival time (years)

Men

HR*:1 .41 (1 .10,1.81), P=0.0060.750.800.850.900.951.00

Pro

porti

on

0 2 4 6 8 10Survival time (years)

Women

HR*:1 .35 (1 .02,1.81), P=0.0380.750.800.850.900.951.00

Pro

po

rtio

n

0 2 4 6 8 10Survival time (years)

Women

Slowest quartile Second quartileThird quartile Fastest quartile

Measured walking speed

Very slow Stroll MediumFairly brisk Fast

Self-reported walking speed

• Self-reported walking speed was strongly associated with measured walking speed.

• Self-reported and measured walking speeds were similarly associated with clinical characteristics and mortality among men and women who participated in HCS.

Key findings

Strengths

• Data obtained from large cohort and were rigorously collected

• Participants comparable with those in the Health Survey for England - results are generalisable (Syddall et al., 2005).

• Analysis adjusted for potential confounders

Weaknesses

• Healthy participant effect

• According to protocol, a small number of HCS men (n=37) and women (n=32) who completed the 3 metre walk test with the use of an assistive device were excluded from the analysis.

SYDDALL et al., 2005. Cohort profile: the Hertfordshire cohort study. Int.J.Epidemiol., 34

Discussion

• First study to investigate whether self-reported walking speed is a useful marker of measured walking speed.

• Results require replication, particularly among groups of older men and women in whom frailty and the use of assistive devices is likely to be greater.

• Self-reported walking speed could serve as a useful marker of physical performance when direct measurement of walking speed is not feasible.

Conclusion

• Study participants• Hertfordshire GPs• Hertfordshire Cohort Study Team

• Dr Holly Syddall, Prof Avan Aihie Sayer and Prof Cyrus Cooper

• Funding: – Medical Research Council – University of Southampton UK

Acknowledgements