Elsevier

Gait & Posture

Volume 49, September 2016, Pages 19-24
Gait & Posture

Full length article
Gait initiation time is associated with the risk of multiple falls—A population-based study

https://doi.org/10.1016/j.gaitpost.2016.06.006Get rights and content

Highlights

  • GI time was associated with multiple falls.

  • GI under dual-task condition was not a stronger measure of falls risk.

  • The strongest measure of falls risk was time to FLM under single task.

  • GI may be an important component of a comprehensive falls risk assessment

Abstract

Aims

In a population-based study of older people to examine whether 1) overall gait initiation (GI) time or its components are associated with falls and 2) GI under dual-task is a stronger predictor of falls risk than under single-task.

Methods

Participants aged 60–85 years were randomly selected from the electoral roll. GI was obtained with a force platform under both single and dual-task conditions. Falls were ascertained prospectively over a 12-month period. Log multinomial regression was used to examine the association between GI time (total and its components) and risk of single and multiple falls. Age, sex and physiological and cognitive falls risk factors were considered as confounders.

Results

The mean age of the sample (n = 124) was 71.0 (SD 6.8) years and 58.9% (n = 73) were male. Over 12 months 21.8% (n = 27) of participants reported a single fall and 16.1% (n = 20) reported multiple falls. Slower overall GI time under both single (RR all per 100 ms 1.28, 95%CI 1.03, 1.58) and dual-task (RR 1.14, 95%CI 1.02, 1.27) was associated with increased risk of multiple, but not single falls (p < 0.05). Multiple falls were also associated with slower time to first lateral movement under single-task (RR 1.90 95%CI 0.59, 1.51) and swing time under dual-task condition (RR 1.44 95%CI 1.08, 1.94).

Conclusion

Slower GI time is associated with the risk of multiple falls independent of other risk factors, suggesting it could be used as part of a comprehensive falls assessment. Time to the first lateral movement under single-task may be the best measures of this risk.

Introduction

Falls occur in over 30% of people older than 60 years living in the community in a one-year period [1], and can result in injury, loss of independence and nursing home admission [2]. Identified risk factors for falls include impaired physiological (e.g. muscle strength, gait, balance) and psychological factors (e.g mood, processing speed and attention), with a greater number of impairments increasing the risk [3]. However, falls remain a significant problem with further investigation of risk factors required in order to identify and prevent older people from falling.

Falls can occur during gait initiation (GI)—the transition stage from standing still to steady state walking [4]. Previous studies have found the slower GI time is associated with impairment in both physiological and cognitive falls-risk factors [5], and prevention of a fall often requires a quick change in posture or a protective step. Taken together these factors indicate that poorer GI time may provide a good summary measure of an individual’s falls-risk.

GI can be described by its three components: Time to the first lateral movement (FLM); FLM to when the lead foot leaves the platform; and from foot off to contact with the adjacent surface [5], [6]. GI time increases whilst performing a simultaneous task in older people [6], such as talking to another person. This is thought to be due to the increased load on executive and attentional resources, which may be limited in older age, and result in slower GI. The competition for attention between the cognitive and GI tasks may further increase risk of falls [7], [8], [9]. Examining the individual components of GI under single and dual-task may assist in further refining the assessment of falls risk and design of effective intervention programs.

Previous findings have differed in the relationship between GI [8], [10], [11], [12] or stepping tests [13] and falls risk, with some reporting an increased risk under single [12], [13] or dual-task [8], [11], [12], while others reported no association under single-task [8], [10]. Conflicting findings may be explained by the use of differing samples including volunteers [8], [10] or residents from retirement villages [11], [12], [13] or by retrospective falls ascertainment, potentially leading to recall bias [8], [10], [11], [13]. To our knowledge there has only been one prospective study, where slower step execution times were associated with recurrent falls [12]. This study included volunteers from retirement homes which may not be generalizable to all older people living in the community.

Therefore, in a population-based sample of older people the aims of this study were to examine whether: 1) overall GI time or its components were associated with falls 2) GI time under dual-task was a stronger predictor of falls risk than under single-task. 3) Whether associations between GI and falls were independent of other physiological and psychological factors. We hypothesized that overall GI time under dual-task would be the strongest predictor of falls independent of other falls risk factors.

Section snippets

Participants

The sample consisted of 128 consecutive participants who completed the GI task from the Tasmanian Study of Cognition and Gait (TASCOG), starting in 2007. The overall larger TASCOG study (n = 431) commenced in 2005 and randomly selected residents from the Southern Tasmanian Electoral roll aged between 60–85 years using age- and sex-stratified random sampling. Participants were excluded if they resided in a nursing home, were unable to walk without the use of a gait aid or if there were any

Gait initiation

GI was measured under single- and dual-task using a 200 Hz AccuGait force-platform and Advanced Mechanical Technology Inc.-NetForce software as described previously [5]. Participants stood on the force-platform with heels spaced by 6 cm and at approximately a 10 degree angle [6]. In the single-task condition participants were asked to start walking in response to a buzzer activated at random times. Under the dual-task condition the participant was asked to count backwards in threes from a number

Data analysis

Differences between those in the full study and those in the GI sub-study were calculated using chi squared analysis (χ2) and t-tests as appropriate. Log multinomial regression was used to estimate the relative risk of single and multiple falls for GI (components and overall time) under single- and dual-task. Gait initiation was presented in 100 ms units to more clearly describe associations for the regression analyses. All models were adjusted for age and sex. Other falls risk measures of

Results

Four participants were excluded (one person had a diagnosis of Parkinson’s disease and 3 had missing falls data), leaving 124 participants. Ninety four percent of participants (n = 117) returned all six questionnaires. During the 12 months follow-up, 62.1% (n = 77) reported no falls and 37.9% (n = 47) reported any fall. Of those who fell, 21.8% (n = 27) a single fall and 16.1% (n = 20) reported two or more falls. Table 1 provides the baseline characteristics of participants. The mean age of the sample

Discussion

In this population-based study of older community-dwelling people, slower overall GI time under single and dual-task was associated with increased risk of multiple falls. The strength of association was slightly stronger under the single compared with dual-task condition. Slower time to FLM conferred the strongest risk of falls under single-task and swing time the strongest risk under dual-task. These results were independent of gait speed and other falls risk factors, supporting the addition

Conflicts of interest

There are no conflicts of interest

Funding

This work was supported by the National Health and Medical Research Council (NHMRC) Grants 403000 and 491109 and an Australian Physiotherapy Research Foundation Grant S0014877. MC is funded by an NHRMC Early Career Fellowship. LB is funded by an NHMRC Career Development Fellowship. VS is a recipient of a National Heart Foundation/National Health and Medical Research Council (NHMRC) Career Development Fellowship and NHMRC project grants. Financial sponsors played no role in the design,

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