Stops walking when talking a predictor of falls in older adults

Stops walking when talking: a predictor of falls in older adults?a Department of Geriatrics & Faculty of Medicine, Angers University Hospital and University of Angers, UNAM, France;bForm

Stops walking when talking: a predictor of falls in older adults?

a

Department of Geriatrics & Faculty of Medicine, Angers University Hospital and University of Angers, UNAM, France;bFormadep, Korian, Paris, France;cDepartment of Neurology & Faculty of Medicine, Geneva University Hospitals, Switzerland;dDepartment of Geriatrics, University of Basel & Basel University Hospital, Switzerland;eDepartment of Geriatrics & Faculty of Medicine, Nantes University Hospital & University of Nantes, UNAM, France; and f Department of Rehabilitation and Geriatrics & Faculty of Medicine, Geneva University Hospitals and University of Geneva, Switzerland

Keywords:

dual-task-related gait

changes, falling, gait,

older adult

Received 29 July 2008

Accepted 18 February 2009

The objective of this study was to systematically review all published articles exam-ining the relationship between the occurrence of falls and changes in gait and atten-tion-demanding task performance whilst dual tasking amongst older adults An English and French Medline and Cochrane library search ranging from 1997 to 2008 indexed under Ôaccidental fallsÕ, Ôaged OR aged, 80 and overÕ, Ôdual taskÕ, Ôdual taskingÕ, ÔgaitÕ, ÔwalkingÕ, ÔfallÕ and ÔfallingÕ was performed Of 121 selected studies, fifteen met the selection criteria and were included in the final analysis The fall rate ranged from 11.1% to 50.0% in retrospective studies and from 21.3% to 42.3% in prospective ones Amongst the three retrospective and eight prospective studies, two and six studies, respectively, showed a significant relationship between changes in gait performance under dual task and history of falls The predictive value for falling was particularly efficient amongst frail older adults compared with healthy subjects Two prospective studies challenged the usefulness of the dual-task paradigm as a significant predictor compared to single task performance and three studies even reported that gait changes whilst dual tasking did not predict falls The pooled odds ratio for falling was 5.3 (95%

CI, 3.1–9.1) when subjects had changes in gait or attention-demanding task perfor-mance whilst dual tasking Despite conflicting early reports, changes in perforperfor-mance whilst dual tasking were significantly associated with an increased risk for falling amongst older adults and frail older adults in particular Description of health status, standardization of test methodology, increase of sample size and longer follow-up intervals will certainly improve the predictive value of dual-task-based fall risk assessment tests

Introduction

Simple and efficient detection of fall risk in older adults

is a major objective of geriatric medicine Twelve years

ago, Lundin-Olsson et al [1] published a seminal paper

that showed that Ôstops walking when talkingÕ could be

a predictor of falls and thus introduced a new approach

to fall prediction based on dual-task performance

The principle of dual-task gait assessment is to

compare task performance whilst walking and

simoul-taneously executing an attention-demanding task to

performance of either one of single tasks [2,3] Changes

in performance whilst dual tasking are usually inter-preted as interference because of competing demands for attentional resources needed for both tasks [3,4] and mainly depend on oneÕs capacity to properly allocate attention between the two tasks [2,3]

Over the past years, dual-task-related gait changes have frequently been reported amongst older adults [4,5] However, published data are heterogeneous and show that impaired dual tasking is [1,6–14] and is not associ-ated with falls [15–17], or is even an irrelevant fall risk indicator compared to impaired single task performance [6,18,19] Using a systematic review of the literature, we selected and analysed all published data, which examined the relationship between fall incidences and changes in gait and/or attention-demanding task performance whilst dual tasking amongst people aged 65 and older and identified the reasons of those conflicting results

Correspondence: Olivier Beauchet, MD, PhD, Department of

Geriatrics, Angers University Hospital, 49933 Angers Cedex 9,

France (tel.: ++33 2 41 35 45 50; fax: ++33 2 41 35 48 94; e-mail:

olbeauchet@chu-angers.fr).

Literature search

An English and French Medline literature search of all

articles published from March 1997 to April 2008 using

the Medical Subject Heading (MeSH) terms Ôaccidental

fallÕ and Ôaged or aged, 80 and overÕ combined with the

terms Ôdual taskÕ, Ôdual taskingÕ, ÔgaitÕ, ÔwalkingÕ, ÔfallÕ

and ÔfallingÕ was performed The search also included

the Cochrane library and the references lists of the

re-trieved articles To ensure a comprehensive approach,

additional key studies known to the authors that did

not meet the search criteria were also included

Study selection and analysis

Abstract selection was based on the STrengthening the

Reporting of OBservational studies in Epidemiology

(STROBE) checklist that described items that should be

included in reports of cohort studies [20] Abstracts

identified with the literature search were independently

evaluated by two reviewers For those abstracts, which

fulfilled the inclusion criteria (observational studies,

retrospective or prospective data collection of falls,

number of falls and motor performance under single

and dual task as outcomes), full articles were obtained

for the final analysis Final selection criteria were

ap-plied when mean age of 65 and older was reached, gait

performance under single and dual task were specified

as outcome measures, and enrolment methods, exact

procedures of dual tasking and discriminative or

pre-dictive values of falls provided The study selection is

shown on a flow diagram (Fig 1)

Twenty-eight of 121 identified abstracts were first

identified after screening using initial inclusion criteria

Thorough revision further excluded 13 studies because

65 (n = 2) [27,28], the cognitive task not described (n = 1) [29] or no measures of the discriminative or predictive value for falls provided (n = 4) [30–33] The remaining 15 studies [1,6–19] were included in this re-view

The association between dual-task-associated gait changes and falls was determined based on the predic-tive value for falling, the odds ratio (OR) for falls with a 95% confidence interval (CI) and the positive and negative predictive value (PPV and NPV) for falls along with sensitivity and specificity

All parameters were calculated for each study using Dag-stat a spreadsheet for the calculation of compre-hensive statistics for the assessment of diagnostic tests and inter-rater agreement that provides a comprehen-sive range of statistics for 2 by 2 tables [34] A meta-analysis was conducted using the STATA software ver-sion 10.1 (Stata Corp., College Station, TX, USA 2007)

to compute pooled OR associated with the risk of falls according to the results from the dual-task procedure either from the exact number of events and non-events when available or to compute an estimated OR (ES) from the natural logarithm transformation of the OR and 95% CI As a result of statistically significant het-erogeneity amongst the studies, the DerSimonian and Laird random effects method was used to estimate the pooled OR 95% CI for the ORs were computed with the Woolf method

Results

Table 1 summarizes the 15 studies included in this re-view Number of participants ranged from 30 to 380 [6,18] Fall rates ranged from 11.1% to 50.0% in retro-spective studies of fall collection [6,14,15] and from

Initial references identified (n = 121)

Abstracts rejected because did not meet the initial criteria

selection (n = 70; Duplication [22], Interventional studies

[10], No dual-task [7], Review [5], Fall not outcome [49])

Meet criteria and were requested (n = 28)

Manuscripts accepted for final inclusion (n = 15)

Manuscripts rejected because did not meet the final criteria

selection (n = 13; balance task as outcome [6], mean age

under 65 [2], cognitive task not described [1], no measures for discriminative or predictive value for falls [4])

Figure 1 Flow diagram of selection of

studies.

Outcomes Follow-up

Sensitivity Specificity Positive

value Negative

value n

Attention-demanding task

Shumway-Cook et

Community-dwelling N

a for

TUG Normal

Community-dwelling N

TUG Normal

Community-dwelling N

TUG Normal

Lundin-Olsson et

TUG Walking

water Conversation

Outcomes Follow-up

Sensitivity Specificity Positive

value Negative

value n

Attention-demanding task

Community-dwelling N

alternatively (complex

6/11(54.6) 41/48

Community-dwelling N

9 95

Bootsma-van Der

6 30

TUG Normal

Conversation To

Outcomes Follow-up

Sensitivity Specificity Positive

value Negative

value n

Attention-demanding task

performance 12months 54(28.9)

Inpatients N

a Mean

b Main

c Median

d Age

e Combined

12 months [1,6–19] Six studies examined frail older

subjects living in senior housing facilities [1,7,8,11,13,19]

Six other studies examined healthy community-dwelling

older adults [6,9,14–16,18] and three studies focused on

inpatients [10,12,17] Ten studies explored association

between dual-task-related changes with the first fall event

[1,7–12,15,17,19] and four with recurrent falls

[6,13,14,16], defined as ‡2 falls during the follow-up

period The type of attention-demanding task

substan-tially differed amongst studies, whereas 11 of them used a

conversation [1,8,10,17], an enumeration of the alphabet

[9] or backward counting [6,11–13,15,19] that

corre-sponded to a spoken verbal task; four studies used a

manual task [6–8,10], one a visuo-spatial decision task

[14] and one a combination of both attention-demanding

tasks [8] Normal paced gait was measured in all studies

[1,6–19] except one study [18] in which subjects walked as

quickly as possible A straight walkway was used in all,

but three studies in which a turn around and return route

was used [9,14,18]

The occurrence of falls was significantly associated

with dual-task-related performance in 11 studies

[1,6-14;19] The highest odds ratio for falling was 56.0 [6]

and the lowest was 1.34 [14] Of the studies with

pro-spective data collection of falls, six [1,7–9,12] reported

that dual-task-related gait changes predicted falls with

specificity ranging from 82.2% to 95.7% but with

sen-sitivity between 38.5% and 84.9% Furthermore, both

PPV and NPV were above 70% in all but two studies,

which reported a PPV under 55% [9,12] Prediction of

falls was based on gait changes in five studies [1,7–

10,12,13,19] and on attention-demanding task changes

in one study [11] This last study showed the highest

sensitivity, specificity, PPV, NPV and OR of all other

studies with prospective data collection of falls

(ad-justed OR = 53.3, P < 0.001) In addition, two

stud-ies challenged the usefulness of the dual-task paradigm

as a predictor of falls compared to single task

perfor-mance [18,19] Although an increase in walking time

whilst dual tasking was significantly associated with the

occurrence of falls (respectively, OR 2.5 [1.3;4.7] and

OR 3.3 [1.3;8.6]), the dual-task paradigm did not bring

any additional information compared to the

ambula-tion time under single task, i.e walking alone [18,19]

Three studies did not find that changes in gait whilst

performing a cognitive task might predict falls

[10,16,17] Inpatients with stroke had changes in gait

during a conversation [17] or whilst carrying a glass of

water [10], yet these changes were not associated with

falls The used dual-task score based on three levels

(normal, doubtful and abnormal) was not associated

with falls in StalenhoefÕs study [16]

were not included in this analysis because of lack of data [15,16] The pooled odds ratio for falling was 1.62 (95% CI, 0.96–2.72) for retrospectives studies and 6.84 (95% CI, 3.06–15.28) for prospective studies, when subjects had changes in gait or attention-demanding task performance whilst dual tasking The pooled odds ratio for falling when analysis included all studies was 5.3 (95% CI, 3.1–9.1)

Discussion

Divergent findings on dual-task-related gait changes, their relationship with falls and their usefulness for fall prediction raise a number of issues They mainly con-cern the methodology, demographics and/or sample recruitment (institutionalized versus community-dwell-ing older adults, differences in health status) and lack of consensus concerning dual-task paradigms

From a methodological point of view, no informa-tion about the number of subjects required to predict falls was reported and studies did not include a post-hoc power analysis As a consequence, equivocal or nega-tive results could be the result of a lack of power [11– 15] Furthermore, follow-up periods ranged from 6 to

12 months Such short follow-up periods may under-estimate the number of falls and thus explain the failure

to establish a relationship with dual-task-related gait changes In addition, primary outcome measures var-ied Some studies examined the first fall following the dual-task assessment [1,6–10,13,14], whilst others examined the predictive value for recurrent falls defined

as‡2 falls during the follow-up period [6,13,14,16] Two out of four studies with equivocal or negative results used the latter outcome measure Because recurrent falls are more often related to intrinsic (i.e subject-re-lated) risk factors for falling than isolated falls [4,5] and dual-task-related gait changes are closely associated with intrinsic risk factors for falling [6], an association between recurrent falls and dual-task-related gait changes could be postulated Intrinsic risk factors for falling are those related to various cumulated effects of chronic diseases and physiologic decline [35] These ef-fects become even more pronounced and diverse with age, contributing to a vicious cycle of increasing frailty and increasing risk of falling The discrepancy between this hypothesis and the results could be related to an insufficient number of studies (i.e 2), which specifically explored the predictive value for recurrent falls Lastly, study samples were very heterogeneous They included frail older adults living in senior housing facilities [1,7,8,11,13] as well as healthy community-dwelling older adults [6,8,11,13–15] or inpatients

[10,12,17] No association between dual-task-related

gait changes and fall incidence was found in the three

studies that focused on community-dwelling older

adults (i.e relatively healthy older adults) [15,16,18] In

contrast, the highest predictive values for falls based on

dual-task-related gait changes were found in

institu-tionalized populations (i.e frail older adults) [1,7,8] and

geriatric inpatients [12] Worsened gait performance

whilst dual tasking was associated with polymedication,

a well-known marker of comorbidities and frailty [36]

Therefore, it might be suggested that gait changes

whilst dual tasking could be a particularly significant

predictor of falls amongst frail older adults

The lack of standardization in dual-task paradigms

certainly explains many of the discrepancies listed

above A consensus needs to be reached on test

condi-tions and data collection In contrast to a

non-stan-dardized attention-demanding task like engaging in a

conversation, a well-defined and quantitative verbal

fluency task, such as reciting letters of the alphabet or

backward counting would improve validity, reliability, consistency and comparison of results [1,8,9,18,19] Few studies gave instructions to participants prior to dual tasking It has been shown that the dual-task interference depended on the priority given to either one of both tasks [2,3], based on the assumption that attentional resources are limited [3] Therefore, inter-ference suggests an overload of the central resources associated with an inability to appropriately allocate attention between two simultaneously performed tasks

or prioritization [2,3,37,38] Thus, gait changes whilst dual tasking, both their nature and their range, might represent the ability to develop a strategy for main-taining optimal movement in terms of attentional de-mand and efficiency of gait control The attention-demanding tasks were qualitatively and quantitatively too heterogeneous, some authors using a relatively simple motor task [6–8,10] and others various cognitive tasks based on spoken verbal responses with varying degrees of difficulty [1,7–14] As a more complex

cog-NOTE: Weights are from random effects analysis

Overall (I-squared = 87.9%, P = 0.000)

Subtotal (I-squared = 78.4%, p = 0.010)

Faulkner et al., 2007*

Subtotal (I-squared = 86.9%, P = 0.000)

Bootsma-Van Der Wiel et al., 2003

Studies with retrospective data collection of falls

Studies with prospective data collection of falls

Andersson et al., 2006†

Verghese et al., 2002*

Verghese et al., 2002†

Lundin-Olsson et al., 1997

Faulkner et al., 2007†

Lundin-Olsson et al., 1998

Lundin-Olsson et al., 2000

Andersson et al., 2006*

Beauchet et al., 2008b

Beauchet et al., 2008a

Shumway-Cook et al., 2000

Hyndman et al., 2004

15.94 (3.22, 79.05)

6.84 (3.06, 15.28)

ES (95%CI)

3.89 (0.86, 17.59) 53.08 (20.65, 136.43)

3.33 (1.29, 8.56)

10.11 (2.00, 50.98)

5.55 (1.10, 28.02)

2.46 (1.28, 4.73)

100.00 79.06

% Weight

5.30 (3.08, 9.13)

.

Kressig et al., 2008

Study ID

Beauchet et al., 2007

1.62 (0.96, 2.72) 1.34 (1.04, 1.74)

0.98 (0.65, 1.47)

7.03 (1.68, 29.43) 13.75 (2.26, 83.56) 25.90 (7.64, 87.77) 15.90 (3.02, 83.88)

1.42 (1.08, 1.85) 56.00 (5.13, 611.71)

2.63 (0.94, 7.38)

5.06 5.01

5.01

6.81 6.19 20.94

5.32

5.54 4.52 4.89

8.58

8.82 8.84 3.28

7.08

7.09 7.98

1

*: Simple attention-demanding task

†: Complex attention-demanding task

Figure 2 Forest plot of the pooled estimated OR (ES) associated with the risk of falls according to the results from the dual-task procedure computed from the natural logarithm transformation of the OR and 95% CI I-squared (variation in OR attributable to heterogeneity).

might greatly depend on the dual task and be related to

a ceiling effect of task used

Walking conditions also varied in the studies As it

has been well-established that a walk route including

walking straight ahead, turning around and returning

required more attention as opposed to walking straight

alone [4,39], such conditions could also influence

dual-task performance [39]

The right choice of dual-task-related parameters

seems to be crucial for fall prediction All, but one of

the studies [11], which explored the predictive value for

falling, were based on changes in gait whilst dual

tasking Most studies used visual observation and

re-corded ambulation time and the number of steps or

stops [1,6–11,13–19], although some authors suggested

its poor inter-rater reliability [40] Only one study [12]

used a spatio-temporal gait analysis system that

al-lowed quantified and objective gait measurements,

showing that increased stride time variability whilst

counting backwards was a significant indicator of fall

risk In addition, unlike most of the previous studies,

one study also evaluated changes in the

attention-demanding task performance whilst counting

back-wards out loud from 50 [11] Subjects were then divided

into two categories, according to their backward

counting performance Subjects who counted more

numbers whilst walking than whilst seated had a higher

risk of falling than those who counted fewer numbers

whilst walking The authors postulated that backward

counting, being both an attention and a rhythmic task,

would act as a regulator, comparable to a metronome

in subjects with an irregular walking pattern and,

therefore, at highest risk of falling [41] Improved

counting performances in this case might be explained

by a phenomenon of the two rhythms, counting and

walking, being drawn toward each other and would be

an indirect way to identify subjects with irregular stride

Despite the use of heterogeneous dual-task conditions,

the pooled OR shows a statistically significant increase

in the risk of falls when subjects had changes in gait or

attention-demanding task performance whilst dual

tasking, this is particularly obvious in prospective

studies

Conclusions

Despite conflicting early reports, changes in

perfor-mance whilst dual-tasking were significantly associated

with an increased risk for falling amongst older adults

(pooled odds ratio = 5.3 with 95% CI = 3.1–9.1)

Recent data, which focused on stride-to-stride

vari-ability and changes in attention-demanding task

per-developing new approaches in fall prevention A better analysis of changes in attention-demanding tasks, gait variability, their relationship with cognitive functions and the search for their anatomical and neurochemical correlates constitute a fascinating challenge [42] To improve the predictive value of dual task-based fall risk assessment tests, more prospective population studies are needed with larger sample sizes, better identification

of confounding variables, such as health status and standardization of the methodology, mainly for the attention-demanding task Such a consensus will cer-tainly improve fall prediction but also response to cognitive treatments such as cholinergic enhancers and other treatments that may be available in the future

Acknowledgment

None

Author contributions

Beauchet has full access to the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analyses Beauchet and Herrmann were responsible for study concept and design Dubost and Annweiler performed the acquisition of data Beauchet, Allali, Herrmann, Kressig, Bridenbaugh, Assal, Dubost and Annweiler performed the analysis and interpretation of data Beauchet, Allali, Annweiler and Dubost was responsible for drafting of the manu-script Annweiler, Herrmann, Kressig, Assal and Bridenbaugh made critical revision of the manuscript for important intellectual content Herrmann was responsible for statistical expertise Dubost and Annweiler gave administrative, technical, or material support Beauchet and Herrmann did study supervi-sion Funding is not applicable

Conflict of interest

The authors have no relevant financial interest in this manuscript

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