Minimal detectable change of gait and balance measures in older neurological patients: estimating the standard error of the measurement from before-after rehabilitation data thanks to the linear mixed-effects models.

BACKGROUND: Tracking gait and balance impairment in time is paramount in the care of older neurological patients. The Minimal Detectable Change (MDC), built upon the Standard Error of the Measurement (SEM), is the smallest modification of a measure exceeding the measurement error. Here, a novel method based on linear mixed-effects models (LMMs) is applied to estimate the standard error of the measurement from data collected before and after rehabilitation and calculate the MDC of gait and balance measures. METHODS: One hundred nine older adults with a gait impairment due to neurological disease (66 stroke patients) completed two assessment sessions before and after inpatient rehabilitation. In each session, two trials of the 10-meter walking test and the Timed Up and Go (TUG) test, instrumented with inertial sensors, have been collected. The 95% MDC was calculated for the gait speed, TUG test duration (TTD) and other measures from the TUG test, including the angular velocity peak (ωpeak) in the TUG test's turning phase. Random intercepts and slopes LMMs with sessions as fixed effects were used to estimate SEM. LMMs assumptions (residuals normality and homoscedasticity) were checked, and the predictor variable ln-transformed if needed. RESULTS: The MDC of gait speed was 0.13 m/s. The TTD MDC, ln-transformed and then expressed as a percentage of the baseline value to meet LMMs' assumptions, was 15%, i.e. TTD should be < 85% of the baseline value to conclude the patient's improvement. ωpeak MDC, also ln-transformed and expressed as the baseline percentage change, was 25%. CONCLUSIONS: LMMs allowed calculating the MDC of gait and balance measures even if the test-retest steady-state assumption did not hold. The MDC of gait speed, TTD and ωpeak from the TUG test with an inertial sensor have been provided. These indices allow monitoring of the gait and balance impairment, which is central for patients with an increased falling risk, such as neurological old persons. TRIAL REGISTRATION: NA.

Pay attention: you can fall! The Mini-BESTest scale and the turning duration of the TUG test provide valid balance measures in neurological patients: a prospective study with falls as the balance criterion.

Background: Balance, i.e., the ability not to fall, is often poor in neurological patients and this impairment increases their risk of falling. The Mini-Balance Evaluation System Test (Mini-BESTest), a rating scale, the Timed Up and Go (TUG) test, and gait measures are commonly used to quantify balance. This study assesses the criterion validity of these measures as balance measures. Methods: The probability of being a faller within nine months was used as the balance criterion. The Mini-BESTest, TUG (instrumented with inertial sensors), and walking test were administered before and after inpatient rehabilitation. Multiple and LASSO logistic regressions were used for the analysis. The diagnostic accuracy of the model was assessed with the area under the curve (AUC) of the receiver operating characteristic curve. Mobility measure validity was compared with the Akaike Information Criterion (AIC). Results: Two hundred and fourteen neurological patients (stroke, peripheral neuropathy, or parkinsonism) were recruited. In total, 82 patients fell at least once in the nine-month follow-up. The Mini-BESTest (AUC = 0.69; 95%CI: 0.62-0.76), the duration of the TUG turning phase (AUC = 0.69; 0.62-0.76), and other TUG measures were significant faller predictors in regression models. However, only the turning duration (AIC = 274.0) and Mini-BESTest (AIC = 276.1) substantially improved the prediction of a baseline model, which only included fall risk factors from the medical history (AIC = 281.7). The LASSO procedure selected gender, disease chronicity, urinary incontinence, the Mini-BESTest, and turning duration as optimal faller predictors. Conclusion: The TUG turning duration and the Mini-BESTest predict the chance of being a faller. Their criterion validity as balance measures in neurological patients is substantial.

Physical Performance and Falling Risk Are Associated with Five-Year Mortality in Older Adults: An Observational Cohort Study.

Background: Falls in older people have a significant impact on public health. The scientific literature has provided evidence about the necessity for older adults to be physically active, since it reduces the incidence of falls, several diseases, and deaths, and can even slow down some effects of aging. The primary aim of our study is to identify if physical performances and risk of falling are related to 1-, 2-, 3-, 4-, and 5-year mortality. Its secondary aim is to establish if people with both severely impaired physical performance and a high risk of falling also present impairment in other geriatric domains. Methods: In this prospective study, we enrolled subjects aged 65 years or more, subjected them to comprehensive assessment (including assessment of risk of falling, physical capacities, comorbidities, autonomies in daily living, cognitive abilities, mood, and nutritional status), and followed them for 5 years. Results: We included 384 subjects, 280 of whom were women (72.7%), with a median age of 81 years. Our results showed that physical performances and risk of falling are highly correlated to each other (rho = 0.828). After divided the sample into three groups (people without augmented risk of falling and able to perform adequate physical activity; people with moderate risk of falling and/or disability; people with severe risk of falling and/or disability), we found that the more severe the disability and risk of falling were, the more compromised the other geriatric domains were. Moreover, the survival probability progressively increased following the same trend, amounting to only 41% in severely compromised people, 51.1% in moderately compromised people, and 62.8% in people without physical compromise nor an augmented falling risk (p = 0.0124). Conclusions: Poor physical performance combined with a high risk of falling, correlated with each other, are associated with higher mortality and impairment in multiple domains in older adults.

Aging effects of haptic input on postural control under a dual-task paradigm.

Postural control relies on three principal sensory systems: vision, vestibular and proprioceptive; that are affected by aging. When performing a cognitive task concomitantly with a motor task, those sensory impairments lead to even greater deleterious effects on balance. We aimed to study the effects of a sensory aid (a light touch) on a dual task paradigm and sought to understand the different responses on balance due to aging. Fifty healthy and highly physical active women were divided in two groups: young (N = 25, 24.2 ± 4.0 years) and older adults (N = 25, 67.3 ± 4.2 years). In a random and balanced order, all participants performed five tasks: Stroop test while seated (Seated); Stroop test while standing quiet (ST); Standing quiet (BL); Standing quiet with a haptic input (LT); and Stroop test with a haptic input while standing quiet (SL). In the Stroop test, older women committed more errors (50 vs 11 errors, p < 0.001) and had higher reaction time (1.001 ± 0.191 vs 0.699 ± 0.081 s, p < 0.001). The haptic input (LT) reduced all body sway parameters, in both groups, regardless the condition. This means that postural control under a dual task paradigm (ST) deleterious effect can be mitigated by a haptic input.

Influence of the Use of Wii Games on Physical Frailty Components in Institutionalized Older Adults.

Aging is a multifactorial physiological phenomenon in which cellular and molecular changes occur. These changes lead to poor locomotion, poor balance, and an increased falling risk. This study aimed to determine the impact and effectiveness of the use of the Wii® game console on improving walking speed and balance, as well as its influence on frailty levels and falling risk, in older adults. A longitudinal study was designed with a pretest/post-test structure. The study population comprised people over 75 years of age who lived in a nursing home or attended a day care center (n = 80; 45 women; 84.2 ± 8.7 years). Forty of them were included in the Wii group (20 rehabilitation sessions during 8 consecutive weeks), and the other 40 were in the control group. Falling risk and frailty were evaluated using the Downton scale and Fried scale; balance and walking speed were assessed with the Berg Balance scale and the Gait Speed Test, respectively, as well as the Short Physical Performance Battery (SPPB). The results showed that there was no significant association between Frailty Phenotype and study groups in baseline. However, there was significant association between Frailty Phenotype and study groups at the end of study. Moreover, a significantly higher and negative percentage change (Δ) in the Wii group with respect to the control group on the in falling risk (-20.05 ± 35.14% vs. 7.92 ± 24.53%) and in walking speed (-6.42 ± 8.83% vs. -0.12 ± 4.51%) during study, while there was a higher and positive significant percent change in static balance (6.07 ± 5.74% vs. 2.13 ± 4.64%) and on the SPPB (20.28 ± 20.05% vs. 0.71 ± 7.99%) after 8 weeks of study. The main conclusion of this study was that the use of the Wii® video console for 8 weeks positively influenced walking speed, falling risk, static balance, and frailty levels in older adults. Through a rehabilitation program with the Wii® game console in the older adults, frailty levels are reduced, accompanied by a reduction in falling risk and an increase in static balance and walking speed.

Differences between two types of dual tasks according to the educational level in older adults.

INTRODUCTION: For dual-task paradigms, the timed up and go (TUG) test along with other cognitive or motor tasks has been used to evaluate and predict the risk of falling in older adults. However, the interference between motor-cognitive tasks can differ by the cognitive task. OBJECTIVE: To evaluate the performance of the TUG test under a single task condition and two dual-task conditions in older adults and to explore the effect of educational level on task performance. METHODS: A total of 418 older adults (328 females) voluntarily participated in this study. The TUG test was administered as a single task and a dual task with one secondary simultaneous task: counting aloud backward from 100 or naming animals. Comparisons were performed to determine the interference caused by each cognitive task on the motor task, and correlation analysis was performed to explore the role of educational level. RESULTS: The animal task led to a poorer TUG performance and a higher dual-task cost than did the counting task. Furthermore, the motor task led to a higher percentage of errors and cognitive stops in the animal task. Educational level plays a significant role in the interaction between tasks. CONCLUSIONS: Between-task interference differs by the type of cognitive task performed and the educational level of the participants. The results of the present study should be considered when dual-task assessments are planned for older adults.

Dual task performance and history of falls in community-dwelling older adults.

INTRODUCTION: Falls are a common problem for older adults, and the identification of people at high risk of falling is a major challenge to health systems. OBJECTIVE: To evaluate the association between the history of falls and single-task Timed Up and Go Test (single TUG) or dual-task TUG variables. METHODS: Three hundred seventy seven community-dwelling older persons, with ages ranging from 65 and 92 years, participated in this cross-sectional study. Each participant performed two tests: single TUG and dual TUG. The cognitive task for dual TUG consisted of counting backward by one from 100 while performing the test. The number of cognitive errors, cognitive stops and motor stops were recorded. A new variable comprising time, errors and stops in the dual TUG was computed. RESULTS: The number of falls was significantly associated with mean single and dual TUG performance, mean cognitive errors, mean cognitive stops and mean motor stops. The score in the single TUG time was not able to significantly classify participants as fallers or non-fallers in any of the sexes. On the other hand, the variable "dual TUG time spent adding cognitive stops and cognitive errors" achieved the best ability to classify women as fallers or non-fallers, while "dual task cost" and "dual TUG time spent adding cognitive stops" were the best variables to classify men. CONCLUSIONS: Dual TUG including cognitive stops and cognitive errors may be more capable than the single TUG to detect differences and accurately classify fallers and non-fallers in the elderly.

A Pilot Study on Falling-Risk Detection Method Based on Postural Perturbation Evoked Potential Features.

In the human-robot hybrid system, due to the error recognition of the pattern recognition system, the robot may perform erroneous motor execution, which may lead to falling-risk. While, the human can clearly detect the existence of errors, which is manifested in the central nervous activity characteristics. To date, the majority of studies on falling-risk detection have focused primarily on computer vision and physical signals. There are no reports of falling-risk detection methods based on neural activity. In this study, we propose a novel method to monitor multi erroneous motion events using electroencephalogram (EEG) features. There were 15 subjects who participated in this study, who kept standing with an upper limb supported posture and received an unpredictable postural perturbation. EEG signal analysis revealed a high negative peak with a maximum averaged amplitude of -14.75 ± 5.99 µV, occurring at 62 ms after postural perturbation. The xDAWN algorithm was used to reduce the high-dimension of EEG signal features. And, Bayesian linear discriminant analysis (BLDA) was used to train a classifier. The detection rate of the falling-risk onset is 98.67%. And the detection latency is 334ms, when we set detection rate beyond 90% as the standard of dangerous event onset. Further analysis showed that the falling-risk detection method based on postural perturbation evoked potential features has a good generalization ability. The model based on typical event data achieved 94.2% detection rate for unlearned atypical perturbation events. This study demonstrated the feasibility of using neural response to detect dangerous fall events.

Standing balance on inclined surfaces with different friction.

Working and walking environments often involve standing positions on different surfaces with inclination and different friction. In this study, standing balance of thirteen participants during sudden and irregular external perturbation to calf muscles was investigated. The aim of the study was to evaluate the combined effect of surface inclination and friction on standing balance. The main findings when eyes closed revealed that the standing utilised coefficient of friction (µSUCOF) increased when the surface was inclined for both high and low friction materials. The anterior-posterior torque increased more anteriorly when the surface was inclined toes down and when the surface friction was low. The results indicate that the anterior-posterior torque is a sensitive parameter when evaluating standing balance ability and slip risk. On inclined surface, particularly on the surface with lower friction, the potential slip and fall risk is higher due to the increase of standing utilised coefficient of friction and increased forward turning torque.

[German translation of the performance-oriented mobility assessment according to Tinetti]. / Deutsche Übersetzung des "Performance-Oriented Mobility Assessment" nach Tinetti.

BACKGROUND: In clinical research as well as good clinical practice increasing importance is placed on standardized and evaluated procedures. They provide information which is important for the prognosis, determination of the need for interventions, determination of treatment goals and evaluation of treatment approaches and outcomes. Furthermore, they serve as justification of the reimbursement for presentation to official bodies. Until now no officially authorized German version of the performance-oriented mobility assessment (POMA) according to Tinetti was available. OBJECTIVES: This article presents a methodically translated German version of the POMA that also includes so far partially unpublished instructions for the examiner and the examined person. MATERIAL AND METHODS: The internationally recognized recommendations for the cross-cultural adaptation of health status measures served as the foundation of the translation process. By means of three translations from the original language into the target language a preliminary consensus version was developed, which was then translated back into the original language by two native speakers. RESULTS AND CONCLUSION: With this new and for the first time authorized German translation of the POMA a version of this assessment is available that achieves unification and standardization in German speaking countries and guarantees an improved comparability with international studies.

Contribuciones de las Ciencias Electrónicas al Problema de las Caídas en Población Adulta Mayor / Contributions of electronic sciences to the problem of falls of old age population

Resumen En este escrito se presenta un estado del arte sobre las contribuciones de las ciencias de la electrónica al problema de las caídas en población adulta mayor. La bibliografía estudiada se clasificó con base en una taxonomía propuesta por los autores consistente de 8 ejes temáticos que son: etiología, epidemiología, predicción, consecuencias, prevención, medición, detección de caídas y detección de actividades diarias. De la revisión bibliográfica realizada se concluyó que las contribuciones más importantes de las ciencias de la electrónica surgen tanto del desarrollo de dispositivos de captura de movimiento como de los diferentes algoritmos propuestos para procesar la información proveniente de estos dispositivos. Gracias a la combinación de estos dos aspectos (dispositivos y algoritmos) se han podido medir de manera precisa variables como velocidad de marcha, longitud y duración del paso, posición del centro de gravedad y balanceo postural. La medición de estas variables, a su vez, ha introducido avances significativos en la forma en que se realiza la valoración del riesgo de caída. Pese a lo anterior, existen numerosos interrogantes que aun deben ser resueltos, uno de ellos es: ¿cómo convertir la información cuantitativa asociada a la medición de variables biomecánicas en valoraciones cualitativas?. De lo anterior se derivan interrogantes más puntuales como: ¿cuáles son los límites aceptables para la asimetría de marcha? ¿Cómo determinar si un nivel de balanceo postural puede considerarse inseguro?

Abstract This paper aims to present a state of the art concerning the contributions of electronic sciences to the problem of falls in elder population. The studied literature was classified based on a taxonomy proposed by the authors, consisting of 8 thematic areas which are: etiology, epidemiology, prediction, consequences, prevention, measurement, detection of falls and detection of daily activities. From the literature review it was concluded that the most important contributions of the electronic sciences emerge from the development of motion capture devices as well as from the different algorithms proposed to process the resulting information generated by these devices. Thanks to the combination of these two aspects (algorithms and devices) it was possible to measure accurately variables as walking speed, length and duration of the step, position of the center of gravity and postural balance. The measurement of these variables, in turn, has introduced significant advances in the form in which the risk of falling is assessed. Despite the above, there are many questions that must still be resolved, one of them is: How to convert the quantitative information associated with measurement of biomechanical variables in to qualitative valuations? From the above, more specific questions arise as: what are the acceptable limits for the asymmetry of the step? How to determine when a level of postural balance can be considered unsafe?

Reliability and validity of the Chinese version of STRATIFY in geriatric inpatients / 中国实用护理杂志

Objective To test the reliability and validity of the Chinese version STRATIFY (St Thomas Risk Assessment Tool in Falling Elderly Inpatients) for geriatric inpatients.Methods The scale was translated and 404 geriatric inpatients were evaluated by the Chinese version STRATIFY and evaluate its reliability and validity.Results Chinese version STRATIFY was found with good feasibility.The Pearson correlation coefficient of reliability between testers was 0.951,the retest reliability was 0.885,internal consistency reliability (Cronbach's αt) was 0.523.The values of item-total correlation was over 0.3.The distinguish validity in difference of STRATIFY scores between groups with/without fall history was statistically significant.Predictive validity was moderate,the best cut-off point was determined at 2 points,and sensitivity and specificity were respectively 64.3％ and 78.2％.Conclusions Chinese version STRATIFY applied in Chinese geriatric inpatients showed good reliability between testers,retest reliability,distinguish validity and predictive validity,and it could be used to assess the fall risk of Chinese geriatric inpatients.In addition,as the internal consistency was lower,we can revise the entry of STRATIFY to provide a more accurate predicting tool.

Dynamic stability control during perturbed walking can be assessed by a reduced kinematic model across the adult female lifespan.

The current study aimed to determine potential differences in dynamic stability control during perturbed walking across the adult female lifespan and to test the hypothesis that such differences can be assessed by a reduced kinematic model. 11 young-aged (22-30years), 9 middle-aged (41-59years) and 14 old-aged (62-75years) female adults walked on a treadmill while the right leg was unexpectedly perturbed once during the swing phase. Margin of stability (MS) at touchdown was investigated using a full body and a reduced kinematic model. After the perturbation, all age groups showed a lower MS compared to non-perturbed gait (baseline), leading to negative MS. Four old-aged adults failed to cope with the task (only preventing a fall by grasping). The remaining ten old-aged and the middle-aged subjects required three more recovery steps than the young-aged adults to get back to baseline MS. Moreover, there were no differences between kinematic models, and both methods demonstrated similar age-related findings. We concluded that the ability to control dynamic stability during perturbed walking by enlarging the base of support has already begun to deteriorate by middle age. Further, the valid agreement between kinematic models shows that such differences can be assessed by using just four body markers.