Application and Interpretation of Functional Outcome Measures for Testing Individuals With Cognitive Impairment

Responsiveness and interpretability of commonly used outcome assessments of mobility capacity in older hospital patients with cognitive spectrum disorders

Background

In older hospital patients with cognitive spectrum disorders (CSD), mobility should be monitored frequently with standardised and psychometrically sound measurement instruments. This study aimed to examine the responsiveness, minimal important change (MIC), floor effects and ceiling effects of commonly used outcome assessments of mobility capacity in older patients with dementia, delirium or other cognitive impairment.

Methods

In a cross-sectional study that included acute older hospital patients with CSD (study period: 02/2015–12/2015), the following mobility assessments were applied: de Morton Mobility Index (DEMMI), Hierarchical Assessment of Balance and Mobility (HABAM), Performance Oriented Mobility Assessment, Short Physical Performance Battery, 4-m gait speed test, 5-times chair rise test, 2-min walk test, Timed Up and Go test, Barthel Index mobility subscale, and Functional Ambulation Categories. These assessments were administered shorty after hospital admission (baseline) and repeated prior to discharge (follow-up). Global rating of mobility change scales and a clinical anchor of functional ambulation were used as external criteria to determine the area under the curve (AUC). Construct- and anchor-based approaches determined responsiveness. MIC values for each instrument were established from different anchor- and distribution-based approaches.

Results

Of the 63 participants (age range: 69–94 years) completing follow-up assessments with mild (Mini Mental State Examination: 19–24 points; 67%) and moderate (10–18 points; 33%) cognitive impairment, 25% were diagnosed with dementia alone, 13% with delirium alone, 11% with delirium superimposed on dementia and 51% with another cognitive impairment. The follow-up assessment was performed 10.8 ± 2.5 (range: 7–17) days on average after the baseline assessment. The DEMMI was the most responsive mobility assessment (all AUC > 0.7). For the other instruments, the data provided conflicting evidence of responsiveness, or evidence of no responsiveness. MIC values for each instrument varied depending on the method used for calculation. The DEMMI and HABAM were the only instruments without floor or ceiling effects.

Conclusions

Most outcome assessments of mobility capacity seem insufficiently responsive to change in older hospital patients with CSD. The significant floor effects of most instruments further limit the monitoring of mobility alterations over time in this population. The DEMMI was the only instrument that was able to distinguish clinically important changes from measurement error.

Trial registration

German Clinical Trials Register (DRKS00005591). Registered February 2, 2015.

Pilot feasibility study of a home-based fall prevention exercise program (StandingTall) delivered through a tablet computer (iPad) in older people with dementia

OBJECTIVE

To assess the feasibility and safety of StandingTall-an individually tailored, progressive exercise program delivered through tablet computers-in community-dwelling older people with dementia.

METHODS

Fifteen community-dwelling older people with dementia (mean age = 83 ± 8 years; Montreal Cognitive Assessment 16 ± 5) received StandingTall for 12 weeks with caregiver assistance. Feasibility and safety were assessed using the System Usability Scale (SUS; scores = 0-100; a priori target >65), Physical Activity Enjoyment Scale (PACES-8; scores = 8-56), adherence (exercise minutes) and adverse events.

RESULTS

Mean SUS scores were 68 ± 21/69 ± 15 (participants/caregivers). The mean PACES-8 score was 44 ± 8. In week 2, week 7 and week 12, mean (bias-corrected and accelerated 95% CI) exercise minutes were 37 (25-51), 49 (30-69) and 65 (28-104), respectively. In week 12, five participants exercised >115 minutes. One participant fell while exercising, without sustained injury.

CONCLUSIONS

StandingTall had acceptable usability, scored well on enjoyment and was feasible for participants. These results provide support for further evaluation of StandingTall in a randomised controlled trial with falls as the primary outcome.

Reliability of mobility measures in older medical patients with cognitive impairment

Background

Mobility is a key indicator of physical functioning in older people, but there is limited evidence of the reliability of mobility measures in older people with cognitive impairment. This study aimed to examine the test-retest reliability and measurement error of common measurement instruments of mobility and physical functioning in older patients with dementia, delirium or other cognitive impairment.

Methods

A cross-sectional study was performed in a geriatric hospital. Older acute medical patients with cognitive impairment, indicated by a Mini-Mental State Examination (MMSE) score of ≤24 points, were assessed twice within 1 day by a trained physiotherapist.

The following instruments were applied: de Morton Mobility Index, Hierarchical Assessment of Balance and Mobility, Performance-Oriented Mobility Assessment, Short Physical Performance Battery, 4-m gait speed, 5-times chair rise test, 2-min walk test, timed up and go test, Barthel Index mobility subscale and Functional Ambulation Categories.

As appropriate, the intraclass correlation coefficient (ICC), Cohen’s kappa, standard error of measurement, limits of agreement and minimal detectable change (MDC) values were estimated.

Results

Sixty-five older acute medical patients with cognitive impairment participated in the study (mean age: 82 ± 7 years; mean MMSE: 20 ± 4, range: 10 to 24 points). Some participants were physically or cognitively unable to perform the gait speed (46%), 2-min walk (46%), timed up and go (51%) and chair rise (75%) tests.

ICC and kappa values were above 0.9 in all instruments except for the gait speed (ICC = 0.86) and chair rise (ICC = 0.72) measures. Measurement error is reported for each instrument. The absolute limits of agreement ranged from 11% (de Morton Mobility Index and Hierarchical Assessment of Balance and Mobility) to 35% (chair rise test).

Conclusions

The test-retest reliability is sufficient (> 0.7) for group-comparisons in all examined instruments. Most mobility measurements have limited use for individual monitoring of mobility over time in older hospital patients with cognitive impairment because of the large measurement error (> 20% of scale width), even though relative reliability estimations seem sufficient (> 0.9) for this purpose.

Trial registration

German Clinical Trials Register (DRKS00005591). Registered 2 February 2015.

Electronic supplementary material

The online version of this article (10.1186/s12877-019-1036-z) contains supplementary material, which is available to authorized users.