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Human Movement and Balance Laboratory, Department of Bioengineering; Falls, Balance, and Injury Research Centre, Neuroscience Research Australia
Jami Stuckeya, Michelle Tsizhovkina, Kurt Beschornera , Erika Plinerb, Daina Sturnieksb, Stephen Lordb
aHuman Movement and Balance Laboratory, Department of Bioengineering, bFalls, Balance, and Injury Research Centre, Neuroscience Research Australia
Jami Stuckey Jami Stuckey is an undergraduate biomedical engineering student at the University of Pittsburgh. Her research interests include biomechanics and rehabilitation engineering. After her time at the Human Movement and Balance Laboratories, she accepted a co-op program with the Human Engineering Research Laboratories.
Kurt Beschorner, Ph.D. Kurt Beschorner is an Associate Professor of Bioengineering at the University of Pittsburgh. He utilizes techniques in tribology, biomechanics and ergonomics to generate understanding and interventions for falling accidents.
Significance Statement
Understanding user-specific factors of ladder fall risk in older adults is important since ladder falls are a frequent cause of injury and fatality among this population. This study found greater risk-taking, as measured by a survey tool, was associated with less use of a safety handrail. Therefore, promoting less risk-taking behaviors may promote safer use of ladders.
Category: Experimental Research
Keywords: Ladder safety, fall risk, handrail use,
user-specific factors, individual factors
Abbreviations: Physiological Profile Assessment (PPA),
Mini-Mental State Exam (MMSE)
Abstract
Unintentional injuries and fatalities caused by ladder falls are especially common among retirement-age adults living independently at home. Past research has focused on environmental factors that increase one’s fall risk, but there is a lack of knowledge on user-specific factors that promote safe ladder use. This study recruited older adult participants to determine the user-specific factors that influence an individual’s ladder handrail use during a domestic ladder task. Two trials of the ladder task were completed, one without a cognitive distraction (single task) and one while naming animals (dual task). Investigated user-specific factors comprised of physical ability, measured by the Physiological Profile Assessment (PPA); global cognition, measured by the Mini-Mental State Exam (MMSE); and risk-taking, measured by a self-assessment. Through Spearman’s ρ correlation analyses, this study found greater risk-taking to be associated with less use of the ladder safety handrail (ρsingle = -0.418, p < 0.0001; ρdual = -0.466, p < 0.0001). Focusing interventions to reduce propensity for risk-taking may promote safer use of ladders.
1. Introduction
Ladder falls are a frequent cause of unintentional injuries and fatalities; the estimated annual cost of ladder injuries in the U.S. is $24 billion [1,2]. Ladder injuries are particularly common among older adults at home (aged 65+ years) [1], but past ladder safety research has focused on falls of adults occurring at the workplace [3-5]. Similar investigation of ladder falls in older people working from home is emerging, yet gaps in our understanding remain. Furthermore, previous research has primarily studied the influence of environmental factors on ladder fall risk [6,7], and there is limited knowledge on user-specific factors that influence safe ladder use.
Handrail use is a presumed safety strategy that can improve balance and enhance a person’s response to a destabilizing balance perturbation [8]. Not all individuals use the ladder handrails while on a stepladder, but there is a lack of knowledge characterizing handrail use. Relevant factors of general fall risk in older adults include physiological, cognitive, and psychological traits and abilities [9]. Thus, these user-specific factors may also be relevant to handrail use.
This study quantifies the relationship of sensorimotor function (physiological factor), global cognition (cognitive factor), and risk taking (psychological factor) with handrail use of older adults when changing a lightbulb on a common household stepladder. The goal of this study is to improve current strategies for preventing unintentional ladder falls. We hypothesized that the user-specific factors would be associated with handrail use.
2. Methods
2.1 Measures
104 older adult participants (Table 1) were recruited for this study. To be eligible for this study, participants were older than 65 years old, living independently at home or in a retirement village, and willing to change a light bulb while standing on the second step of a stepladder.
Age (yrs) Height (m) Weight (kg)
Male (52)
65 – 89
1.57 – 1.93
55.3 – 113.2
Table 1: Participant Demographics
Female (52)
65 – 87
1.51 – 1.82
46.5 – 93.3
Exclusion criteria included the use of a mobility aid inside the home, a neurological disorder (e.g. Parkinson’s disease, multiple sclerosis, dementia/Alzheimer’s), weight over 120 kg, and the inability to change a light bulb on a ladder without pain. This study was approved by the Human Studies Ethics Committee at the University of New South Wales and informed consent was obtained prior to participation.
Participants completed several clinical assessments. The Physiological Profile Assessment (PPA) [10], Mini-Mental State Exam (MMSE) [11], and an assessment of everyday risk-taking [12] were selected as a priori individual measures for this study to quantify the contribution of physical and cognitive ability and psychological state on safe ladder use. The PPA, measured by a summative Z-Score, captured measures of sensorimotor function (visual, reaction time, proprioception, strength, balance) that are predictive of fall risk [10]. This study used the PPA measure as a metric of physical ability, where a high Z-Score indicates reduced sensorimotor function. Higher scores on the MMSE indicate better global cognition [11]. Higher scores on the risk-taking assessment reflect a higher propensity to take risks in everyday activities (e.g. crossing the street after the Do Not Walk sign starts flashing) [12]. 2.2 Data Collection
Participants were asked to climb a stepladder, replace a lightbulb, and descend the ladder (Figure 1). Use of the handrail at the top of the ladder was optional and participants were not given any instruction regarding whether to use the handrails. The height of the light bulb was positioned to the participant’s hand height when standing on the second ladder step with 90° shoulder and elbow flexion.
Figure 1: Ladder Setup. The lightbulb fixture was fixed to a wood and aluminum frame with an adjustable height. The stepladder had a tray and a handrail. The tray was used to hold the replacement lightbulb.
Two trials of this task for each participant were collected: one without a cognitive distraction (single task) and one while naming animals (dual task). The two different tasks were chosen to assess the influence of cognitive demand; however, the focus of this manuscript will be the userspecific factors. Participants practiced changing the lightbulb at ground level prior to the trials. These two trials were in a random order for each participant and participants were asked to complete the task “as quickly and safely as possible.”
Videos were captured of participants completing the ladder tasks. These videos were analyzed to quantify handrail use. The duration of handrail use was recorded, called “Rail Time.” This was measured across two independent observers and averaged. 2.3 Statistical Analysis
Non-parametric correlation analyses (Spearman’s ρ) were performed because rail time was bimodal. Correlations were performed between the rail time and user-specific measures of physical ability (PPA Z-score), global cognition (MMSE score), and risk taking. Separate analyses were performed for the two tasks. (single task, dual task) using JMP Pro 14. An alpha value of 0.05 was used for statistical significance.
3. Results
The median rail time during the single task was 1.56 s (IQR: 0-7.58 s). The median rail time during dual task was 1.02 s (IQR: 0-12.89 s). Increased rail time use was weakly correlated with reduced physical ability, lower global cognition, and moderately associated with less risk-taking (Table 2 and Figure 2).
Dependent Variable Independent Variable Single Task Dual Task
Rail Time PPA1 Spearman’s ρ p-value Spearman’s ρ
0.235 0.024* 0.179 p-value
0.095
Rail Time MMSE2 -0.209 0.048* -0.229 0.032*
Rail Time RiskTaking3 -0.418 <0.0001* -0.466 <0.0001*
1 Physical Profile Assessment measures physiological factor 2 Mini-mental state exam score measures cognitive factor 3 Risk taking score measures psychological factor * significant p-value (< 0.05) Table 2: Spearman’s ρ correlation coefficients for each individual measure by task. Figure 2 (right): User-Specific Factors vs. Rail Time. Scatter plot of Single Task and Dual Task rail use time with linear trend lines for a) Physiological Factor (PPA z-score) b) Cognitive Factor (MMSE score), and c) Psychological Factor (risk-taking score)
4. Discussion
The results of the correlation analyses support the hypothesis that user-specific factors correlate with handrail use. Reduced physical ability, lower cognition, and decreased risk-taking are associated with increased rail time.
Individuals may use the handrail to compensate for their reduced physical and cognitive abilities. Furthermore, reduced physical and cognitive function is predictive of a greater fall risk in older adults [13]. Therefore, handrail use may reduce the fall risk of these individuals during ladder use. Individuals with higher global cognition and better physical ability showed reduced handrail use. These individuals may not require the supplementary assistance to safely complete the task. This is supported by another study in which older adults’ confidence in their stair climbing stability was assessed found that individuals with lower confidence used the handrail to a greater extent and positioned themselves closer to the rail [14]. Additionally, self-identified risk-takers are less likely to use the handrail. This is supported by other studies in which risk-taking / riskier behavior was associated with stair falls [14,15].
Possible limitations of this study include that one specific factor was tested and generalized for each broader factor (physiological, cognitive, and psychological) when perhaps the PPA, MMSE, and the risk-taking assessment may not be representative of an individual’s entire physical ability, mental capacity, or psychological state. Additionally, only task performance of individuals changing a light bulb on a household stepladder was tested. Future research is required to determine individuals measures that influence ladder task performance across different tasks and ladder designs.
5. Conclusions
This research found that rail grasping time is correlated with user-specific factors, including physical ability (ρsingle = 0.235, p < 0.024; ρdual = 0.179, p < 0.095) and global cognition (ρsingle = -0.209, p < 0.038; ρdual = -0.229, p < 0.042). Rail grasping time was also strongly associated with risk-taking (ρsingle = -0.418, p < 0.0001; ρdual = -0.466, p < 0.0001). This suggests that user-specific factors influence handrail use, especially psychological factors. Thus, focusing on the ladder task and reducing risk taking propensity may promote safer use of ladders.
6. Acknowledgements
This research was funded by the Whitaker International Program and the National Institute for Occupational Safety and Health (R01OH011799).
7. References
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