Assessment of Thigh Angular Velocity by an Activity Monitor to Describe Sit-to-Stand Performance.

The assessment of sit-to-stand (STS) performance is highly relevant, especially in older persons, but testing STS performance in the laboratory does not necessarily reflect STS performance in daily life. Therefore, the aim was to validate a wearable sensor-based measure to be used under unsupervised daily life conditions. Since thigh orientation from horizontal to vertical is characteristic for STS movement, peak angular velocity (PAV) of the thigh was chosen as the outcome variable. A total of 20 younger and older healthy persons and geriatric patients (mean age: 55.5 ± 20.8 years; 55% women) with a wide range of STS performance were instructed to stand up from a chair at their usual pace. STS performance was measured by an activity monitor, force plates, and an opto-electronic system. The association between PAV measured by the thigh-worn activity monitor and PAV measured by the opto-electronic system (gold standard) was r = 0.74. The association between PAV measured by the thigh-worn activity monitor and peak power measured by force plate and opto-electronic system was r = 0.76. The Intra-Class Coefficient (ICC) of agreement between the 2 trials was ICC(A,1) = 0.76. In this sample of persons with a wide range of physical performance, PAV as measured by a thigh-worn acceleration sensor was a valid and reliable measure of STS performance.

Fall risk as a function of time after admission to sub-acute geriatric hospital units.

BACKGROUND: There is evidence about time-dependent fracture rates in different settings and situations. Lacking are data about underlying time-dependent fall risk patterns. The objective of the study was to analyse fall rates as a function of time after admission to sub-acute hospital units and to evaluate the time-dependent impact of clinical factors at baseline on fall risk. METHODS: This retrospective cohort study used data of 5,255 patients admitted to sub-acute units in a geriatric rehabilitation clinic in Germany between 2010 and 2014. Falls, personal characteristics and functional status at admission were extracted from the hospital information system. The rehabilitation stay was divided in 3-day time-intervals. The fall rate was calculated for each time-interval in all patients combined and in subgroups of patients. To analyse the influence of covariates on fall risk over time multivariate negative binomial regression models were applied for each of 5 time-intervals. RESULTS: The overall fall rate was 10.2 falls/1,000 person-days with highest fall risks during the first week and decreasing risks within the following weeks. A particularly pronounced risk pattern with high fall risks during the first days and decreasing risks thereafter was observed in men, disoriented people, and people with a low functional status or impaired cognition. In disoriented patients, for example, the fall rate decreased from 24.6 falls/1,000 person-days in day 2-4 to about 13 falls/1,000 person-days 2 weeks later. The incidence rate ratio of baseline characteristics changed also over time. CONCLUSIONS: Fall risk differs considerably over time during sub-acute hospitalisation. The strongest association between time and fall risk was observed in functionally limited patients with high risks during the first days after admission and declining risks thereafter. This should be considered in the planning and application of fall prevention measures.

Assessment of fatigability of older women during sit-to-stand performance.

BACKGROUND: Fatigability of older adults is relevant with regard to physical performance, falls and physical activity. Objective and inexpensive assessment tools for testing fatigability in the persons' home environment are not available. AIMS: The aim of this study was to develop a protocol to objectively measure fatigability during repeated sit-to-stand performance in older persons. METHODS: Decrease of maximum velocity of performance during repeated sit-to-stand transfers and the number of repetition when achieving a 10, 15, and 20 % fatigue threshold were measured in 49 community-dwelling older women using a linear encoder. RESULTS: Mean maximum velocity of the sit-to-stand performance was 1.12 m/s (SD 0.17 m/s) with an estimated change of velocity per repetition of -0.0037 m/s (95 % CI -0.0039 to -0.0035) during the test. The mean number of repetitions representing 10, 15, and 20 % fatigue threshold was 8.1, 13.8, and 21, respectively. DISCUSSION: This simple test protocol provides objective information about the decrease of performance of a daily task in older adults. CONCLUSION: Fatigability of the sit-to-stand performance can be measured objectively by measuring the decrease of maximum velocity of consecutive repetitions and the repetition number achieving a 20 % fatigue threshold.

Assessment of balance in unsupported standing with elderly inpatients by force plate and accelerometers.

BACKGROUND AND AIMS: Unsupported standing is one of the most important functional tasks involving balance control. Unlike younger people, who have been shown to counteract imbalance preferably with an ankle strategy, older people tend to do so with a hip strategy. These strategies can be described by matching balance measures at floor and hip level, a good match representing an ankle-dominant strategy and a low one a hip-dominant strategy. The aim of this study was to show possible change in the association between force platform measurement at floor level and accelerometry at hip level in elderly inpatients standing unsupported during rehabilitation. METHODS: Forty four elderly inpatients (mean age 82.5 yrs) after hip fracture or stroke were recruited for the study. Balance was assessed after admission and 2 weeks later on a force platform at floor level and simultaneously by a tri-axial accelerometer at hip level. RESULTS: The correlation between the 2 measures was initially poor to fair (r=0.04 to r=0.51), but increased after 2 weeks of rehabilitation (r=0.30 to r=0.66). CONCLUSIONS: A change in the association between measures obtained at lower back level and floor level may indicate a change from a hip- to an ankle-dominant strategy, to counteract imbalance during unsupported standing.

Assessing Physical Activity in Inpatient Rehabilitation: validity, practicality, and sensitivity to change in the physical activity in inpatient rehabilitation assessment.

OBJECTIVE: To validate a novel assessment of inpatient physical activity. DESIGN: Prospective cohort study for the evaluation of a novel questionnaire for physical activity in geriatric inpatients. SETTING: German geriatric inpatient rehabilitation unit. PARTICIPANTS: Patients (N=96; 67 [72%] women; median age, 81y) with a variety of main underlying diagnoses, including musculoskeletal diseases, hip fracture, cardiovascular diseases, stroke, and others. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Ceiling and floor effects and administration time were measured. For criterion-related concurrent validity (convergent and discriminative), the Physical Activity in Inpatient Rehabilitation Assessment (PAIR) was administered in parallel to self-rated, proxy-rated, and performance-based measures of physical function at admission. Measurements were repeated at discharge and 4-month follow-up in the home environment, including a standard physical activity questionnaire to determine predictive validity. Spearman correlation coefficients were calculated to describe associations between parameters. Sensitivity to change was estimated using standardized response means (SRMs). RESULTS: Administration time of the PAIR ranged from less than 1 to 4 minutes. Ceiling effects occurred mainly at discharge (5%-14%), and floor effects (5%-11%), at admission. There were no missing values. Associations between convergent and predictive validity measures and functional measures (r=.43-.53, r=.49-.54, respectively) were clearly better when cognition was intact. Discriminative validity expressed as effect sizes ranged from .27 to 1.44. The SRM to describe sensitivity to change was .65 for the total score. CONCLUSIONS: The PAIR is the first validated questionnaire to assess physical activity in geriatric inpatients. It is practical and its validity and sensitivity to change are similar to existing physical activity questionnaires for community-dwelling older persons.

Assessment of physical activity in older people with and without cognitive impairment.

The purpose of this study was to validate a new interview-administered physical activity questionnaire (Assessment of Physical Activity in Frail Older People; APAFOP) in older people with and without cognitive impairment. The authors assessed feasibility, validity, and test-retest reliability in 168 people (n = 78 with, n = 88 without cognitive impairment). Concurrent validity was assessed against an inertia-based motion sensor and an established questionnaire. Sensitivity to change was tested in an ongoing study in patients with mild to moderate dementia (n = 81). Assessment of physical activity by the APAFOP and the motion sensor correlated well in the total sample (TS; p = .705), as well as in the subsamples with cognitive impairment (CI; p = .585) and without CI (p = .787). Excellent feasibility with an acceptance rate of 100%, test-retest reliability (intraclass correlation coefficients ranging from .973 (TS) to .975 (CI) to .966 (no CI), and sensitivity to change (effect sizes: 0.35-1.47) were found in both subsamples.