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Postural stability in the elderly: Fallers versus non-fallers
European Geriatric Medicine 2 (2011) 1–5
Research paper
Postural stability in the elderly: Fallers versus non-fallers M. La´zaro a,*, A. Gonza´lez a, G. Latorre a, C. Ferna´ndez b, J.M. Ribera a a b
Department of Geriatric Medicine (Falls Unit), Hospital Clı´nico San Carlos, Dr. Martı´n Lagos s/n., 28040 Madrid, Spain Deparment of Preventive Medicine, Hospital Clı´nico San Carlos, Madrid, Spain
A R T I C L E I N F O
A B S T R A C T
Article history: Received 2 November 2010 Accepted 15 November 2010 Available online 14 December 2010
Objectives: (1) To compare static and dynamic balance alterations in recurrent fallers and non-fallers elderly patients. (2) To assess the functional repercussions of balance disorders and falls in these subjects. Patients and methods: Retrospective, observational, case-control study. The patients examined were 226 community-dwelling elderly people aged over 65 years, 113 of whom had suffered more than two falls in the past 6 months, and a further 113 who had not fallen in the past 6 months. All subjects had received primary care (at one of Madrid’s Area 7 Healthcare Centres) and/or had been outpatients of the Geriatrics Unit and were subjected to an exhaustive examination including the collection of demographic data, geriatric assessment, physical examination, tests of gait and balance and balance control assessment using the Balance Master1. This last assessment included the tests: (1) modified clinical test for sensory interaction on balance (mCTSIB), which estimates sensory balance by measuring the centre of gravity (COG) sway velocity and alignment relative to the centre of the patient’s base of support with open then closed eyes, and on a firm then unstable surface; (2) weight-bearing squat (WBS); (3) rhythmic weight shift; (4) sit to stand (SS); (5) walk across (WA); and (6) step up/over (SUO). Statistical analysis was performed using SPSS v.12.0 software. Results: Recurrent fallers showed greater postural instability when visual and proprioceptive conditions changed than non-fallers, especially when both sensory inputs were simultaneously abolished. The speed of displacement of the centre of gravity on a foam surface was increased in the fallers both with open (p < 0.001) or closed eyes (p = 0.001). In the SS test, fallers took longer to stand from sitting without help (p < 0.001). The WA test results indicated a higher gait speed for the non-fallers (p = 0.001). Conclusions: Assessing postural control systems and identifying neurological fall risk factors in patients who undergo recurrent falls is the key to adopting appropriate measures to prevent subsequent falls and thus minimize their physical, psychological and social consequences. ß 2010 Elsevier Masson SAS and European Union Geriatric Medicine Society. All rights reserved.
Keywords: Aged Posture Balance Gait speed Falls
1. Introduction Falls represent a major health problem for the elderly and it is one of the main causes of injury, disability and even death. It has been reported that a third of community-dwelling elderly persons undergo at least one fall per year [1]. This figure increases with age [2,3] and is higher in subjects who are frail [4] and in those living outside the family environment [5]. In a study conducted in Spain, Salva´ et al. observed that 25.1% of the men and 37.0% of the women living in the community had fallen once a year; and 3.8% of the men and 10.9% of the women in their series had fallen two or more times [6]. Falls are the most common and lethal accidents that occur in elderly persons [7–9]. Their contributing risk factors may be
* Corresponding author. E-mail address: [email protected] (M. La´zaro).
intrinsic (related to the patient) or extrinsic (related to the patient’s activity or environment) [10–12]. Poor balance and mobility are significant predictors of long-term mortality independently of baseline and intermediate events [13]. Hence, postural control plays an important role and is, in turn, determined by sensory input (visual, vestibular and propioceptive systems), by an appropriate processing by the information cortex receives, and by an efficient motor response (muscles, joints, reflexes). An alteration at any of these levels will increase the risk a person has of falling. In addition there are different falls and fallers profiles. Assessing such fall profiles could be helpful to develop preventive programs in the elderly [14]. The aetiology of a fall is often multifactorial. In current clinical practice it is important to carry out a careful geriatric evaluation to every patient who has experienced a fall. It should include: (a) a thorough anamnesis; (b) an exhaustive geriatric assessment; (c) a general physical examination with a special attention to sense organs; (d) tests of balance and gait; (e) assessment of the patient’s
1878-7649/$ – see front matter ß 2010 Elsevier Masson SAS and European Union Geriatric Medicine Society. All rights reserved. doi:10.1016/j.eurger.2010.11.007
M. La´zaro et al. / European Geriatric Medicine 2 (2011) 1–5
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environment; and (f) complementary exams if necessary [15]. Balance assessment using force platform systems has been introduced to identify patients at high risk of falling. The technique provides information on the contribution of each sensorial input involved in maintaining balance and on any displacements in the centre of gravity position [16]. The present study was designed to: describe possible alterations in static and dynamic postural stability in elderly persons defined as recurrent fallers compared to a control group of non-fallers; assess the functional repercussions of these disorders and of the falls suffered by these subjects.
2. Methods 2.1. Type of study Observational, retrospective case-control study.
centre of gravity and to perform basic daily living activities. Through different tests, the instrument assesses the sensory control of balance, since vision and proprioception are known to affect postural control. We used the test ‘‘Modified Clinical Test for Sensory Interaction on Balance’’ (mCTSIB), which estimates balance by measuring the sway velocity of the centre of gravity and the amount of displacement with open then closed eyes, on a firm then unstable surface. Some tests quantify displacement from the centre of gravity during different movements. In this way, both the force and time needed for the subject to adapt to the movement maintaining his/her centre of gravity over the base of support can be determined. In other words, the motor control of balance is assessed. In this study, we used two such tests: Weight-Bearing Squat (WBS). This test measures a subject’s capacity to equally distribute the weight borne by each leg while standing or squatting in different positions of knee flexion; Rhythmic Weight Shift (RWS). This test measures a subject’s ability to coordinate the speed and amplitude of voluntary COG movements.
2.2. Sample size Two hundred and twenty-six subjects (113 recurrent fallers and 113 controls).
The Balance Master1 also serves to identify any existing functional impairment and to objectively quantify the underlying functional limitation. The following tests were used to determine the state of functional independence:
2.2.1. Inclusion criteria for case subjects The case subjects were patients aged 65 years or more who had undergone two or more falls in the previous 6 months and had visited their General Practitioner (GP) (at a health centre in Madrid’s Area 7) and/or a Geriatrician (Geriatrics Unit of the Hospital Clı´nico San Carlos, Madrid) for this reason. 2.2.2. Inclusion criteria for control subjects The control subjects were patients aged 65 years or older who had not fallen in the previous 6 months and had visited their GP or a geriatrician because of a medical problem other than falling. Patients with severe cognitive deterioration were not included in the study, as well as patients that were unable to stand or were terminally ill. All the participants were informed of the procedures and objectives of the study before giving their consent to participate. 2.3. Data collection Each subject (fallers and non-fallers) was interviewed to complete a structured questionnaire with the following data: demographic data (name, age, gender, telephone number), history of falls (circumstances, clinical outcome and consequences of falls), biomedical data (pharmacological history, nutritional state, general physical examination, cardiovascular exam (blood pressure on sitting and standing), musculoskeletal assessment (functional limitation), sense organs exam, neurological exam, balance and gait tests (Romberg test, Timed Up and Go test (TUG) [17], Performance-Orientated Mobility Assessment test (POMA) [18], functional assessment (Katz [19], Lawton [20], Barthel indexes [21], mental state assessment (Mini Mental State Examination [22], Yesavage Geriatric Depression Scale [23], and social assessment data.
Sit to Stand (SS): in this test, the time taken for the individual to rise from a seated to a standing position without any form of help (e.g., push off) is determined; Walk Across (WA): the WA determines the gait trajectory and speed as the subject walks along the length of the force platform; Step Up/Over (SUO): the SUO assesses the balance and coordination achieved through the force exerted by the legs (expressed as percentage body weight) as the subject steps up and down from a step. 2.5. Statistical analysis Quantitative data are expressed as means and their corresponding standard deviation. For extremely asymmetric data, the centralisation measure used was the median and the measure of dispersion was the corresponding interquartile range (IR). Qualitative data are given as frequency or contingency tables, depending on whether we were dealing with one or more than one variable. Associations between variables were estimated using Chi2 test and the effect size using the ‘‘odds ratio’’ and corresponding 95% confidence interval (CI). Quantitative variables were compared between groups using the Student’s t-test and/or the non-parametric median test. Relationships among quantitative variables were assessed using Pearson’s correlation coefficients or the Spearman correlation coefficient as a non-parametric measure. Logistic regression models were used to assess the independent factors related to being a faller. Stratified analyses were performed to detect interactions and adjusted odds ratios and their 95% CIs obtained. In each contrast, the null hypothesis was rejected when the alpha error was less than 0.05. All statistical tests were conducted using the computer package SPSS v. 12.0. 3. Results
2.4. Complementary procedures used to assess falls due to balance and/or gait abnormalities Balance Master1 (NeuroCom International Inc., USA) [16]: This instrument evaluates the capacity of an individual to control the
Our final study population was comprised of 113 patients (85% women) of mean age 78 years ( 5), who had undergone at least two falls in the past 6 months, and 113 control subjects who had not fallen over the same length of time.
M. La´zaro et al. / European Geriatric Medicine 2 (2011) 1–5
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Table 1 Balance and gait assessment tests. Test
Case (%)
Control (%)
OR
95% CI
P
Timed up and go > 20 s Global Tinetti < 18 points Gait speed < 39 cm/s
51.3 38.9 71.4
2.7 3.5 28.4
38.6 17.3 6.2
11.5–128.9 5.9–50.5 3.3–11.6
< 0.001 < 0.001 < 0.001
Table 2 Univariate analysis of cases versus controls: functional tests. Test
Cases (N = 99)
Controls (N = 113)
P
Weight bearing–squat (WBS) at different positions of knee flexion Mean (SD) % weight 08 left 308 left 608 left 908 left
50.61 49.79 50.53 49.93
51.35 51.44 52.42 52.68
0.413 0.078 0.057 0.006
Walk across (WA) Mean (SD) speed cm/s
34.3 (19.4)
49.5 (19.8)
0.001
Step up/over (SUO) Mean (SD) % body weight Lift-up index (left) Lift-up index (right) Impact index (left) Impact index (right)
12.90 14.91 22.38 26.16
15.57 17.85 23.66 26.50
0.011 0.019 0.561 0.882
Sit to stand (SS) Median (IR) seconds
1.82 (0.93–3.73)
Functional tests used to assess balance and gait are listed in Table 1. Fallers and non-fallers differed considerably in scores obtained in these tests, with fallers showing a slower gait speed and lower TUG and overall Tinetti (Tinetti balance and gait tests) test scores. Tables 2 and 3 show the results of our univariate analysis. Table 4 provides the strengths of the associations examined. Our results for the mCTSIB test, in which we assessed the subject’s displacement of the COG while standing on a unstable surface with eyes open or closed, indicate in our study that fallers showed a greater tendency to displace their centre of gravity than control subjects. When balance was tested on a foam surface with eyes open, speeds recorded were 1.348/s (IR: 1.0–2.6) versus 0.98/s (IR: 0.7–1.3) (p < 0.001). Speeds for cushioned surface/eyes closed increased to 3.78/s (IR 2.0–6.0) in fallers and up to 2.08/s (IR: 1.3– 3.4) (p = 0.001) in controls. Table 3 Univariate analysis of cases versus controls: sensory and motor control of balance. Test
Cases (N = 99)
Controls (N = 113)
(6.03) (7.44) (13.76) (13.97)
(5.47) (5.99) (6.65) (6.41)
(6.72) (7.08) (12.84) (12.55)
0.93 (0.49–4.31)
< 0.001
In the RWS test, we noted modifications in forward-backward direction control (p = 0.004). The time taken to stand from a sitting position without help (SS) was longer for the fallers, their median score being 1.82 s (IR: 0.93–3.73) compared to 0.93 s (IR: 0.49– 4.31) for the non-fallers (p < 0.001). Fallers undertook a slower series of movements to adopt a standing position, regardless of their age. Mean ( SD) gait speed recorded for the study subjects was 49.5 ( 19.8) cm/s compared to 34.3 ( 19.4) cm/s for the fallers (p = 0.001). Non-fallers showed a faster gait speed in the WA test. Force, expressed in terms of percentage body weight (mean SD), exerted when stepping onto the step with the right leg was 14.9 kg ( 7.4) compared to 17.8 kg ( 7.0) for the controls (p = 0.01). Mean force exerted by the left leg stepping up was 12.9 ( 6.0) kg for control sample versus 15.5 kg ( 6.7) for fallers (p = 0.01).
4. Discussion
P
Modified clinical test for sensory interaction on balance (mCTSIB) (degrees/second) Firm surface, eyes open 0.4 (0.3–0.5) 0.4 (0.3–0.5) 0.065 Firm surface, eyes closed 0.5 (0.4–0.7) 0.4 (0.3–0.6) 0.032 Foam surface, eyes open 1.4 (1.0–2.6) 0.9 (0.7–1.3) < 0.001 Foam surface, eyes closed 3.7 (2.0–6.0) 2.0 (1.3–3.4) 0.001 Rhythmic weight shift (RWS) Speed Degrees/second Right-left slow Right-left moderate Right-left fast Back-forwards slow Back-forwards moderate Back-forwards fast
3.6 5.5 8.3 1.6 1.8 2.2
(2.5–4.9) (4.4–6.3) (6.0–10.3) (1.2–1.9) (1.2–1.9) (1.4–3.1)
3.9 (3.3–5.0) 6.6 (5.4–7.8) 11.3 (8.9–13.0) 1.4 (1.2–1.8) 2.3 (1.5–2.6) 3.1 (2.7–4.2)
0.16 0.83 0.40 0.07 0.35 0.90
Directional control (%) Right-left slow Right-left moderate Right-left fast Back-forwards slow Back-forwards mod. Back-forwards fast
71 76 80 46 48 55
(62–76) (70–81) (73–84) (30–60) (32–62) (35–69)
74 78 84 56 57 59
0.13 0.90 0.40 0.54 0.06 0.004
(69–79) (74–82) (78–87) (46–71) (43–74) (44–68)
(7.45) (7.45) (7.59) (7.89)
Both static and dynamic postural stability are achieved through the interactions between sensory receptors found in the vestibular, visual and somatosensory systems, and the central nervous system and musculoskeletal reflex arcs. Force-plate instruments, such as the Balance Master1 used here, are useful to identify patients at risk of falling and to assess the balance, or postural, stability of patients who repeatedly fall. Here, we report the results obtained in a study conducted using the Balance Master1 to measure several variables related to balance and gait in a group of recurrent fallers, comparing these with the results obtained in an aged-matched group of non-fallers. The use of this type of instrument to assess patients undergoing recurrent falls has been scarcely reported in the literature and similar studies to ours have only recently started to appear [24– 26]. Our findings indicate that elderly persons who regularly fall show greater instability when confronted with a change in visual and proprioreceptive conditions than elderly subjects who are not so prone to falling. This postural instability is aggravated if both
M. La´zaro et al. / European Geriatric Medicine 2 (2011) 1–5
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Table 4 Strength of associations: odds ratio crude and adjusted for age and gender. Test
Crude OR 95%CI
P
Adjusted OR 95%CI
P
Modified clinical test for sensory interaction on balance (mCTSIB), (degrees/second) Firm surface, eyes open 2.4 (0.7–8.2) Firm surface, eyes closed 2.0 (0.9–4.5) Foam surface, eyes open 1.4 (1.2–1.7) Foam surface, eyes closed 1.3 (1.1–1.6)
0.12 0.05 < 0.001 < 0.001
3.1 2.3 1.5 1.4
(0.7–12.4) (1.0–5.3) (1.2–1.8) (1.2–1.7)
0.07 0.02 < 0.001 < 0.001
Rhythmic weight shift (RWS) Speed (degrees/second) Right-left slow Right-left moderate Right-left fast Back-forwards slow Back-forwards moderate Back-forwards fast
0.15 < 0.001 < 0.001 0.60 0.004 0.001
0.8 0.7 0.7 1.0 0.6 0.7
(0.7–1.0) (0.6–0.8) (0.7–0.8) (0.7–1.6) (0.4–0.8) (0.5–0.8)
0.07 < 0.001 < 0.001 0.67 0.006 0.003
Weight-bearing squat (WBS) at different positions of knee flexion 08 left 0.9 (0.9–1.0) 308 left 0.9 (0.9–1.0) 608 left 0.9 (0.9–1.0) 908 left 0.9 (0.9–0.9)
0.40 0.07 0.05 0.005
0.9 0.9 0.9 0.9
(0.9–1.0) (0.9–1.0) (0.9–1.0) (0.9–0.9
0.70 0.16 0.11 0.01
Walk across (WA)
0.9 (0.9–0.9)
< 0.001
0.9 (0.9–0.9)
< 0.001
Sit to stand (SS)
1.2 (1.1–1.4)
< 0.001
1.2 (1.1–1.4)
< 0.001
Step up/over (SUO) Mean (SD) % body weight Lift-up index (left) Lift-up index (right) Impact index (left) Impact index (right)
0.9 0.9 0.9 0.9
0.01 0.01 0.94 0.87
0.9 0.9 0.9 1.0
0.02 0.07 0.75 0.10
0.8 0.7 0.7 1.1 0.6 0.7
(0.7–1.0) (0.6–0.8) (0.7–0.8) (0.7–1.6) (0.4–0.8) (0.5–0.8)
(0.8 (0.9 (0.9 (0.9
visual and proprioceptive inputs are abolished. Studies on dynamic postural stability have suggested that older individuals are more dependent on propioceptive afferents [24]. Moreover, vision is used to a lesser extent to offset any difficulties. Thus, objective information on the sensory deficiencies that provoke balance disorders in a given patient is extremely useful for preventing new falls. In our study, non-fallers took less time to adopt a standing position from sitting, regardless of age. Fallers showed a slower gait speed than non-fallers. Further, the non-falling elderly subjects used a force equivalent to a higher body weight proportion when stepping onto and down from a step with both legs than those who underwent falls, irrespective of their age or gender. These observations could be explained by the postfall syndrome and its effects on basic daily living activities. Postfall syndrome mainly implies a fear of subsequent falling and loss of confidence for performing a given task without falling, along with impaired mobility and functional capacity. In our study subjects, 90% of the recurrent fallers suffered postfall syndrome. The main advantage of clinical functional postural stability tests is their capacity to detect abnormal components of mobility when performing basic daily living activities. These tools give an idea of the origin of each impairment and help predict the overall risks for the subject while conducting daily tasks. Several authors have established a link between postfall syndrome and the results of postural control tests [27–28]. The early identification of this syndrome helps the physician to plan medical interventions and specific rehabilitation programmes according to the impairments identified and to adopt specific measures to adapt the patient’s environment and provide technical help necessary. Referring patients at a high risk of falling to the different geriatric care levels (day-center, nursing homes etc.) is the key to efficient prevention. For the reasons discussed above, the Balance Master1 can be said to provide extremely useful complementary information for diagnosis and for establishing the treatments necessary and objectively assessing the functional limitations of a patient who has suffered several falls. It also enables objective comparisons
(0.8–0.9) (0.9–1.0) (0.9–1.0) (0.9–1.0)
among recurrently falling patients, eliminating interobserver variability and providing relevant follow-up data [29–30]. In conclusion, the assessment of postural control systems in recurrent fallers is essential to design the prevention measures needed to minimize both the physical and psychological/social consequences of falls in elderly persons. mCTSIB assessment appears to be a sensitive tool for identifying those at high risk of recurrent falls. The Balance Master1 estimates not only postural balance, but reproduces the physiological conditions of daily life and may be used for the early assessment of gait problems and risk of falling. These simple and safe laboratory tests were able to differentiate between elderly fallers and elderly individuals who did not fall, suggesting their possible clinical application as a preliminary screening tool for predicting the risk of falling in the future. Conflict of interest statement Nothing declared. Acknowledgements Author contributions: Montserrat La´zaro and Alfonso Go´nzalez took part in the design, methods, subject recruitment, data collection, analysis and preparation of the article. Cristina Ferna´ndez contributed to the design, methods, analysis and preparation of the article. German Latorre was involved in the subject recruitment and data collections. Jose Manuel Ribera participated in the design, methods, and revision. Financial Disclosure: The study was supported by a grant from the Fondo de Investigaciones Sanitarias (FIS 04/934), Ministerio de Sanidad, Spain. Montserrat La´zaro, Alfonso Gonza´lez, German Latorre, Cristina Ferna´ndez and Jose Manuel Ribera all have no financial disclosures to report. Sponsor’s role: No sponsor.
M. La´zaro et al. / European Geriatric Medicine 2 (2011) 1–5
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Research paper
Postural stability in the elderly: Fallers versus non-fallers M. La´zaro a,*, A. Gonza´lez a, G. Latorre a, C. Ferna´ndez b, J.M. Ribera a a b
Department of Geriatric Medicine (Falls Unit), Hospital Clı´nico San Carlos, Dr. Martı´n Lagos s/n., 28040 Madrid, Spain Deparment of Preventive Medicine, Hospital Clı´nico San Carlos, Madrid, Spain
A R T I C L E I N F O
A B S T R A C T
Article history: Received 2 November 2010 Accepted 15 November 2010 Available online 14 December 2010
Objectives: (1) To compare static and dynamic balance alterations in recurrent fallers and non-fallers elderly patients. (2) To assess the functional repercussions of balance disorders and falls in these subjects. Patients and methods: Retrospective, observational, case-control study. The patients examined were 226 community-dwelling elderly people aged over 65 years, 113 of whom had suffered more than two falls in the past 6 months, and a further 113 who had not fallen in the past 6 months. All subjects had received primary care (at one of Madrid’s Area 7 Healthcare Centres) and/or had been outpatients of the Geriatrics Unit and were subjected to an exhaustive examination including the collection of demographic data, geriatric assessment, physical examination, tests of gait and balance and balance control assessment using the Balance Master1. This last assessment included the tests: (1) modified clinical test for sensory interaction on balance (mCTSIB), which estimates sensory balance by measuring the centre of gravity (COG) sway velocity and alignment relative to the centre of the patient’s base of support with open then closed eyes, and on a firm then unstable surface; (2) weight-bearing squat (WBS); (3) rhythmic weight shift; (4) sit to stand (SS); (5) walk across (WA); and (6) step up/over (SUO). Statistical analysis was performed using SPSS v.12.0 software. Results: Recurrent fallers showed greater postural instability when visual and proprioceptive conditions changed than non-fallers, especially when both sensory inputs were simultaneously abolished. The speed of displacement of the centre of gravity on a foam surface was increased in the fallers both with open (p < 0.001) or closed eyes (p = 0.001). In the SS test, fallers took longer to stand from sitting without help (p < 0.001). The WA test results indicated a higher gait speed for the non-fallers (p = 0.001). Conclusions: Assessing postural control systems and identifying neurological fall risk factors in patients who undergo recurrent falls is the key to adopting appropriate measures to prevent subsequent falls and thus minimize their physical, psychological and social consequences. ß 2010 Elsevier Masson SAS and European Union Geriatric Medicine Society. All rights reserved.
Keywords: Aged Posture Balance Gait speed Falls
1. Introduction Falls represent a major health problem for the elderly and it is one of the main causes of injury, disability and even death. It has been reported that a third of community-dwelling elderly persons undergo at least one fall per year [1]. This figure increases with age [2,3] and is higher in subjects who are frail [4] and in those living outside the family environment [5]. In a study conducted in Spain, Salva´ et al. observed that 25.1% of the men and 37.0% of the women living in the community had fallen once a year; and 3.8% of the men and 10.9% of the women in their series had fallen two or more times [6]. Falls are the most common and lethal accidents that occur in elderly persons [7–9]. Their contributing risk factors may be
* Corresponding author. E-mail address: [email protected] (M. La´zaro).
intrinsic (related to the patient) or extrinsic (related to the patient’s activity or environment) [10–12]. Poor balance and mobility are significant predictors of long-term mortality independently of baseline and intermediate events [13]. Hence, postural control plays an important role and is, in turn, determined by sensory input (visual, vestibular and propioceptive systems), by an appropriate processing by the information cortex receives, and by an efficient motor response (muscles, joints, reflexes). An alteration at any of these levels will increase the risk a person has of falling. In addition there are different falls and fallers profiles. Assessing such fall profiles could be helpful to develop preventive programs in the elderly [14]. The aetiology of a fall is often multifactorial. In current clinical practice it is important to carry out a careful geriatric evaluation to every patient who has experienced a fall. It should include: (a) a thorough anamnesis; (b) an exhaustive geriatric assessment; (c) a general physical examination with a special attention to sense organs; (d) tests of balance and gait; (e) assessment of the patient’s
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M. La´zaro et al. / European Geriatric Medicine 2 (2011) 1–5
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environment; and (f) complementary exams if necessary [15]. Balance assessment using force platform systems has been introduced to identify patients at high risk of falling. The technique provides information on the contribution of each sensorial input involved in maintaining balance and on any displacements in the centre of gravity position [16]. The present study was designed to: describe possible alterations in static and dynamic postural stability in elderly persons defined as recurrent fallers compared to a control group of non-fallers; assess the functional repercussions of these disorders and of the falls suffered by these subjects.
2. Methods 2.1. Type of study Observational, retrospective case-control study.
centre of gravity and to perform basic daily living activities. Through different tests, the instrument assesses the sensory control of balance, since vision and proprioception are known to affect postural control. We used the test ‘‘Modified Clinical Test for Sensory Interaction on Balance’’ (mCTSIB), which estimates balance by measuring the sway velocity of the centre of gravity and the amount of displacement with open then closed eyes, on a firm then unstable surface. Some tests quantify displacement from the centre of gravity during different movements. In this way, both the force and time needed for the subject to adapt to the movement maintaining his/her centre of gravity over the base of support can be determined. In other words, the motor control of balance is assessed. In this study, we used two such tests: Weight-Bearing Squat (WBS). This test measures a subject’s capacity to equally distribute the weight borne by each leg while standing or squatting in different positions of knee flexion; Rhythmic Weight Shift (RWS). This test measures a subject’s ability to coordinate the speed and amplitude of voluntary COG movements.
2.2. Sample size Two hundred and twenty-six subjects (113 recurrent fallers and 113 controls).
The Balance Master1 also serves to identify any existing functional impairment and to objectively quantify the underlying functional limitation. The following tests were used to determine the state of functional independence:
2.2.1. Inclusion criteria for case subjects The case subjects were patients aged 65 years or more who had undergone two or more falls in the previous 6 months and had visited their General Practitioner (GP) (at a health centre in Madrid’s Area 7) and/or a Geriatrician (Geriatrics Unit of the Hospital Clı´nico San Carlos, Madrid) for this reason. 2.2.2. Inclusion criteria for control subjects The control subjects were patients aged 65 years or older who had not fallen in the previous 6 months and had visited their GP or a geriatrician because of a medical problem other than falling. Patients with severe cognitive deterioration were not included in the study, as well as patients that were unable to stand or were terminally ill. All the participants were informed of the procedures and objectives of the study before giving their consent to participate. 2.3. Data collection Each subject (fallers and non-fallers) was interviewed to complete a structured questionnaire with the following data: demographic data (name, age, gender, telephone number), history of falls (circumstances, clinical outcome and consequences of falls), biomedical data (pharmacological history, nutritional state, general physical examination, cardiovascular exam (blood pressure on sitting and standing), musculoskeletal assessment (functional limitation), sense organs exam, neurological exam, balance and gait tests (Romberg test, Timed Up and Go test (TUG) [17], Performance-Orientated Mobility Assessment test (POMA) [18], functional assessment (Katz [19], Lawton [20], Barthel indexes [21], mental state assessment (Mini Mental State Examination [22], Yesavage Geriatric Depression Scale [23], and social assessment data.
Sit to Stand (SS): in this test, the time taken for the individual to rise from a seated to a standing position without any form of help (e.g., push off) is determined; Walk Across (WA): the WA determines the gait trajectory and speed as the subject walks along the length of the force platform; Step Up/Over (SUO): the SUO assesses the balance and coordination achieved through the force exerted by the legs (expressed as percentage body weight) as the subject steps up and down from a step. 2.5. Statistical analysis Quantitative data are expressed as means and their corresponding standard deviation. For extremely asymmetric data, the centralisation measure used was the median and the measure of dispersion was the corresponding interquartile range (IR). Qualitative data are given as frequency or contingency tables, depending on whether we were dealing with one or more than one variable. Associations between variables were estimated using Chi2 test and the effect size using the ‘‘odds ratio’’ and corresponding 95% confidence interval (CI). Quantitative variables were compared between groups using the Student’s t-test and/or the non-parametric median test. Relationships among quantitative variables were assessed using Pearson’s correlation coefficients or the Spearman correlation coefficient as a non-parametric measure. Logistic regression models were used to assess the independent factors related to being a faller. Stratified analyses were performed to detect interactions and adjusted odds ratios and their 95% CIs obtained. In each contrast, the null hypothesis was rejected when the alpha error was less than 0.05. All statistical tests were conducted using the computer package SPSS v. 12.0. 3. Results
2.4. Complementary procedures used to assess falls due to balance and/or gait abnormalities Balance Master1 (NeuroCom International Inc., USA) [16]: This instrument evaluates the capacity of an individual to control the
Our final study population was comprised of 113 patients (85% women) of mean age 78 years ( 5), who had undergone at least two falls in the past 6 months, and 113 control subjects who had not fallen over the same length of time.
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Table 1 Balance and gait assessment tests. Test
Case (%)
Control (%)
OR
95% CI
P
Timed up and go > 20 s Global Tinetti < 18 points Gait speed < 39 cm/s
51.3 38.9 71.4
2.7 3.5 28.4
38.6 17.3 6.2
11.5–128.9 5.9–50.5 3.3–11.6
< 0.001 < 0.001 < 0.001
Table 2 Univariate analysis of cases versus controls: functional tests. Test
Cases (N = 99)
Controls (N = 113)
P
Weight bearing–squat (WBS) at different positions of knee flexion Mean (SD) % weight 08 left 308 left 608 left 908 left
50.61 49.79 50.53 49.93
51.35 51.44 52.42 52.68
0.413 0.078 0.057 0.006
Walk across (WA) Mean (SD) speed cm/s
34.3 (19.4)
49.5 (19.8)
0.001
Step up/over (SUO) Mean (SD) % body weight Lift-up index (left) Lift-up index (right) Impact index (left) Impact index (right)
12.90 14.91 22.38 26.16
15.57 17.85 23.66 26.50
0.011 0.019 0.561 0.882
Sit to stand (SS) Median (IR) seconds
1.82 (0.93–3.73)
Functional tests used to assess balance and gait are listed in Table 1. Fallers and non-fallers differed considerably in scores obtained in these tests, with fallers showing a slower gait speed and lower TUG and overall Tinetti (Tinetti balance and gait tests) test scores. Tables 2 and 3 show the results of our univariate analysis. Table 4 provides the strengths of the associations examined. Our results for the mCTSIB test, in which we assessed the subject’s displacement of the COG while standing on a unstable surface with eyes open or closed, indicate in our study that fallers showed a greater tendency to displace their centre of gravity than control subjects. When balance was tested on a foam surface with eyes open, speeds recorded were 1.348/s (IR: 1.0–2.6) versus 0.98/s (IR: 0.7–1.3) (p < 0.001). Speeds for cushioned surface/eyes closed increased to 3.78/s (IR 2.0–6.0) in fallers and up to 2.08/s (IR: 1.3– 3.4) (p = 0.001) in controls. Table 3 Univariate analysis of cases versus controls: sensory and motor control of balance. Test
Cases (N = 99)
Controls (N = 113)
(6.03) (7.44) (13.76) (13.97)
(5.47) (5.99) (6.65) (6.41)
(6.72) (7.08) (12.84) (12.55)
0.93 (0.49–4.31)
< 0.001
In the RWS test, we noted modifications in forward-backward direction control (p = 0.004). The time taken to stand from a sitting position without help (SS) was longer for the fallers, their median score being 1.82 s (IR: 0.93–3.73) compared to 0.93 s (IR: 0.49– 4.31) for the non-fallers (p < 0.001). Fallers undertook a slower series of movements to adopt a standing position, regardless of their age. Mean ( SD) gait speed recorded for the study subjects was 49.5 ( 19.8) cm/s compared to 34.3 ( 19.4) cm/s for the fallers (p = 0.001). Non-fallers showed a faster gait speed in the WA test. Force, expressed in terms of percentage body weight (mean SD), exerted when stepping onto the step with the right leg was 14.9 kg ( 7.4) compared to 17.8 kg ( 7.0) for the controls (p = 0.01). Mean force exerted by the left leg stepping up was 12.9 ( 6.0) kg for control sample versus 15.5 kg ( 6.7) for fallers (p = 0.01).
4. Discussion
P
Modified clinical test for sensory interaction on balance (mCTSIB) (degrees/second) Firm surface, eyes open 0.4 (0.3–0.5) 0.4 (0.3–0.5) 0.065 Firm surface, eyes closed 0.5 (0.4–0.7) 0.4 (0.3–0.6) 0.032 Foam surface, eyes open 1.4 (1.0–2.6) 0.9 (0.7–1.3) < 0.001 Foam surface, eyes closed 3.7 (2.0–6.0) 2.0 (1.3–3.4) 0.001 Rhythmic weight shift (RWS) Speed Degrees/second Right-left slow Right-left moderate Right-left fast Back-forwards slow Back-forwards moderate Back-forwards fast
3.6 5.5 8.3 1.6 1.8 2.2
(2.5–4.9) (4.4–6.3) (6.0–10.3) (1.2–1.9) (1.2–1.9) (1.4–3.1)
3.9 (3.3–5.0) 6.6 (5.4–7.8) 11.3 (8.9–13.0) 1.4 (1.2–1.8) 2.3 (1.5–2.6) 3.1 (2.7–4.2)
0.16 0.83 0.40 0.07 0.35 0.90
Directional control (%) Right-left slow Right-left moderate Right-left fast Back-forwards slow Back-forwards mod. Back-forwards fast
71 76 80 46 48 55
(62–76) (70–81) (73–84) (30–60) (32–62) (35–69)
74 78 84 56 57 59
0.13 0.90 0.40 0.54 0.06 0.004
(69–79) (74–82) (78–87) (46–71) (43–74) (44–68)
(7.45) (7.45) (7.59) (7.89)
Both static and dynamic postural stability are achieved through the interactions between sensory receptors found in the vestibular, visual and somatosensory systems, and the central nervous system and musculoskeletal reflex arcs. Force-plate instruments, such as the Balance Master1 used here, are useful to identify patients at risk of falling and to assess the balance, or postural, stability of patients who repeatedly fall. Here, we report the results obtained in a study conducted using the Balance Master1 to measure several variables related to balance and gait in a group of recurrent fallers, comparing these with the results obtained in an aged-matched group of non-fallers. The use of this type of instrument to assess patients undergoing recurrent falls has been scarcely reported in the literature and similar studies to ours have only recently started to appear [24– 26]. Our findings indicate that elderly persons who regularly fall show greater instability when confronted with a change in visual and proprioreceptive conditions than elderly subjects who are not so prone to falling. This postural instability is aggravated if both
M. La´zaro et al. / European Geriatric Medicine 2 (2011) 1–5
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Table 4 Strength of associations: odds ratio crude and adjusted for age and gender. Test
Crude OR 95%CI
P
Adjusted OR 95%CI
P
Modified clinical test for sensory interaction on balance (mCTSIB), (degrees/second) Firm surface, eyes open 2.4 (0.7–8.2) Firm surface, eyes closed 2.0 (0.9–4.5) Foam surface, eyes open 1.4 (1.2–1.7) Foam surface, eyes closed 1.3 (1.1–1.6)
0.12 0.05 < 0.001 < 0.001
3.1 2.3 1.5 1.4
(0.7–12.4) (1.0–5.3) (1.2–1.8) (1.2–1.7)
0.07 0.02 < 0.001 < 0.001
Rhythmic weight shift (RWS) Speed (degrees/second) Right-left slow Right-left moderate Right-left fast Back-forwards slow Back-forwards moderate Back-forwards fast
0.15 < 0.001 < 0.001 0.60 0.004 0.001
0.8 0.7 0.7 1.0 0.6 0.7
(0.7–1.0) (0.6–0.8) (0.7–0.8) (0.7–1.6) (0.4–0.8) (0.5–0.8)
0.07 < 0.001 < 0.001 0.67 0.006 0.003
Weight-bearing squat (WBS) at different positions of knee flexion 08 left 0.9 (0.9–1.0) 308 left 0.9 (0.9–1.0) 608 left 0.9 (0.9–1.0) 908 left 0.9 (0.9–0.9)
0.40 0.07 0.05 0.005
0.9 0.9 0.9 0.9
(0.9–1.0) (0.9–1.0) (0.9–1.0) (0.9–0.9
0.70 0.16 0.11 0.01
Walk across (WA)
0.9 (0.9–0.9)
< 0.001
0.9 (0.9–0.9)
< 0.001
Sit to stand (SS)
1.2 (1.1–1.4)
< 0.001
1.2 (1.1–1.4)
< 0.001
Step up/over (SUO) Mean (SD) % body weight Lift-up index (left) Lift-up index (right) Impact index (left) Impact index (right)
0.9 0.9 0.9 0.9
0.01 0.01 0.94 0.87
0.9 0.9 0.9 1.0
0.02 0.07 0.75 0.10
0.8 0.7 0.7 1.1 0.6 0.7
(0.7–1.0) (0.6–0.8) (0.7–0.8) (0.7–1.6) (0.4–0.8) (0.5–0.8)
(0.8 (0.9 (0.9 (0.9
visual and proprioceptive inputs are abolished. Studies on dynamic postural stability have suggested that older individuals are more dependent on propioceptive afferents [24]. Moreover, vision is used to a lesser extent to offset any difficulties. Thus, objective information on the sensory deficiencies that provoke balance disorders in a given patient is extremely useful for preventing new falls. In our study, non-fallers took less time to adopt a standing position from sitting, regardless of age. Fallers showed a slower gait speed than non-fallers. Further, the non-falling elderly subjects used a force equivalent to a higher body weight proportion when stepping onto and down from a step with both legs than those who underwent falls, irrespective of their age or gender. These observations could be explained by the postfall syndrome and its effects on basic daily living activities. Postfall syndrome mainly implies a fear of subsequent falling and loss of confidence for performing a given task without falling, along with impaired mobility and functional capacity. In our study subjects, 90% of the recurrent fallers suffered postfall syndrome. The main advantage of clinical functional postural stability tests is their capacity to detect abnormal components of mobility when performing basic daily living activities. These tools give an idea of the origin of each impairment and help predict the overall risks for the subject while conducting daily tasks. Several authors have established a link between postfall syndrome and the results of postural control tests [27–28]. The early identification of this syndrome helps the physician to plan medical interventions and specific rehabilitation programmes according to the impairments identified and to adopt specific measures to adapt the patient’s environment and provide technical help necessary. Referring patients at a high risk of falling to the different geriatric care levels (day-center, nursing homes etc.) is the key to efficient prevention. For the reasons discussed above, the Balance Master1 can be said to provide extremely useful complementary information for diagnosis and for establishing the treatments necessary and objectively assessing the functional limitations of a patient who has suffered several falls. It also enables objective comparisons
(0.8–0.9) (0.9–1.0) (0.9–1.0) (0.9–1.0)
among recurrently falling patients, eliminating interobserver variability and providing relevant follow-up data [29–30]. In conclusion, the assessment of postural control systems in recurrent fallers is essential to design the prevention measures needed to minimize both the physical and psychological/social consequences of falls in elderly persons. mCTSIB assessment appears to be a sensitive tool for identifying those at high risk of recurrent falls. The Balance Master1 estimates not only postural balance, but reproduces the physiological conditions of daily life and may be used for the early assessment of gait problems and risk of falling. These simple and safe laboratory tests were able to differentiate between elderly fallers and elderly individuals who did not fall, suggesting their possible clinical application as a preliminary screening tool for predicting the risk of falling in the future. Conflict of interest statement Nothing declared. Acknowledgements Author contributions: Montserrat La´zaro and Alfonso Go´nzalez took part in the design, methods, subject recruitment, data collection, analysis and preparation of the article. Cristina Ferna´ndez contributed to the design, methods, analysis and preparation of the article. German Latorre was involved in the subject recruitment and data collections. Jose Manuel Ribera participated in the design, methods, and revision. Financial Disclosure: The study was supported by a grant from the Fondo de Investigaciones Sanitarias (FIS 04/934), Ministerio de Sanidad, Spain. Montserrat La´zaro, Alfonso Gonza´lez, German Latorre, Cristina Ferna´ndez and Jose Manuel Ribera all have no financial disclosures to report. Sponsor’s role: No sponsor.
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