Brief Composite Mobility Index Predicts Post-Stroke Fallers After Hospital Discharge

Introduction: Community-dwelling, ambulatory stroke survivors fall at very high rates in the first 3-6 months. Current inpatient clinical assessments for fall risk have inadequate predictive accuracy. We found that a pre-discharge obstacle-crossing test has excellent specificity (83%) but lacks acceptable sensitivity (67%) for identifying would-be fallers and non-fallers post discharge. Hypothesis: We assessed the hypothesis that combining the obstacle-crossing test with other highly discriminatory fall risk factors would compensate for the obstacle test’s fair sensitivity and yield an instrument with superior prediction accuracy. Methods: 45 ambulatory stroke survivors (60±11 years old, 15±11 days post stroke) being discharged home completed a battery of physical performance-based and self-reported measures 1-5 days prior to discharge. After discharge, participants were prospectively followed and classified as fallers (≥1 fall) or non-fallers at 3 months. Pre-discharge measures with the largest effect sizes for differentiating fallers and non-fallers were combined into a composite index. Several variations of the composite index were examined to optimize accuracy. Results: A 4-item discharge composite index significantly predicted fall status at 3-months. The goodness of fit of the regression model was significantly better than the obstacle-crossing test alone, χ2(1) = 6.036, p=0.014. Furthermore, whereas the obstacle-crossing test had acceptable overall accuracy (AUC 0.78, 95% CI 0.60-0.90), the composite index had excellent accuracy (AUC 0.85, 95% CI 0.74-0.96). Combining the obstacle-crossing test with only the step test produced a model of equivalent accuracy (AUC 0.85, 95% CI 0.73-0.96) and with better symmetry between sensitivity and specificity (0.71, 0.83) than the 4-item composite index (0.86, 0.67). This 2-item index was validated in an independent sample of n=30 and with bootstrapping 1000 samples from the pooled cohorts. The 4-item index was internally validated with bootstrapping 1000 samples from the derivation cohort plus n=9 additional participants. Conclusion: This study provides convincing proof-of-concept that strategic aggregation of performance-based and self-reported mobility measures, including a novel and demanding obstacle-crossing test, can predict post-discharge fallers with excellent accuracy. Further instrument development is warranted to construct a brief aggregate tool that will be pragmatic for inpatient use and improve identification of future post-stroke fallers before the first fall

Brief composite mobility index predicts post-stroke fallers after hospital discharge

IntroductionCommunity-dwelling, ambulatory stroke survivors fall at very high rates in the first 3–6 months. Current inpatient clinical assessments for fall risk have inadequate predictive accuracy. We found that a pre-discharge obstacle-crossing test has excellent specificity (83%) but lacks acceptable sensitivity (67%) for identifying would-be fallers and non-fallers post discharge.HypothesisWe assessed the hypothesis that combining the obstacle-crossing test with other highly discriminatory fall risk factors would compensate for the obstacle test’s fair sensitivity and yield an instrument with superior prediction accuracy.Methods45 ambulatory stroke survivors (60 ± 11 years old, 15 ± 11 days post stroke) being discharged home completed a battery of physical performance-based and self-reported measures 1–5 days prior to discharge. After discharge, participants were prospectively followed and classified as fallers (≥1 fall) or non-fallers at 3 months. Pre-discharge measures with the largest effect sizes for differentiating fallers and non-fallers were combined into a composite index. Several variations of the composite index were examined to optimize accuracy.ResultsA 4-item discharge composite index significantly predicted fall status at 3-months. The goodness of fit of the regression model was significantly better than the obstacle-crossing test alone, χ2(1) = 6.036, p = 0.014. Furthermore, whereas the obstacle-crossing test had acceptable overall accuracy (AUC 0.78, 95% CI, 0.60–0.90), the composite index had excellent accuracy (AUC 0.85, 95% CI, 0.74–0.96). Combining the obstacle-crossing test with only the step test produced a model of equivalent accuracy (AUC 0.85, 95% CI, 0.73–0.96) and with better symmetry between sensitivity and specificity (0.71, 0.83) than the 4-item composite index (0.86, 0.67). This 2-item index was validated in an independent sample of n = 30 and with bootstrapping 1,000 samples from the pooled cohorts. The 4-item index was internally validated with bootstrapping 1,000 samples from the derivation cohort plus n = 9 additional participants.ConclusionThis study provides convincing proof-of-concept that strategic aggregation of performance-based and self-reported mobility measures, including a novel and demanding obstacle-crossing test, can predict post-discharge fallers with excellent accuracy. Further instrument development is warranted to construct a brief aggregate tool that will be pragmatic for inpatient use and improve identification of future post-stroke fallers before the first fall

Feasibility of dual-task gait training for communitydwelling adults after stroke: a case series. Stroke Res

This case series explored the feasibility and efficacy of cognitive-motor dual-task gait training in community-dwelling adults within 12 months of stroke. A secondary aim was to assess transfer of training to different dual-task combinations. Seven male participants within 12 months of stroke participated in 12 sessions of dual-task gait training. We examined single and dual-task performance in four different dual-task combinations at baseline, after 6 and 12 sessions, and if possible, at 1-month followup. Feasibility was assessed by asking participants to rate mental and physical fatigue, perceived difficulty, anxiety, and fear of falling at the end of each session. Five of the seven participants demonstrated reduced dual-task cost in gait speed in at least one of the dual-task combinations after the intervention. Analysis of the patterns of interference in the gait and cognitive tasks suggested that the way in which the participants allocated their attention between the simultaneous tasks differed across tasks and, in many participants, changed over time. Dual-task gait training is safe and feasible within the first 12 months after stroke, and may improve dual-task walking speed. Individuals with a combination of physical and cognitive impairments may not be appropriate for dual-task gait training

Effects of gait and cognitive task difficulty on cognitive-motor interference in aging

Although gait-related dual-task interference in aging is well established, the effect of gait and cognitive task difficulty on dual-task interference is poorly understood. The purpose of this study was to examine the effect of gait and cognitive task difficulty on cognitive-motor interference in aging. Fifteen older adults (72.1 years, SD 5.2) and 20 young adults (21.7 years, SD 1.6) performed three walking tasks of varying difficulty (self-selected speed, fast speed, and fast speed with obstacle crossing) under single-and dual-task conditions. The cognitive tasks were the auditory Stroop task and the clock task. There was a significant Group × Gait Task × Cognitive Task interaction for the dual-task effect on gait speed. After adjusting for education, there were no significant effects of gait or cognitive task difficulty on the dual-task effects on cognitive task performance. The results of this study provide evidence that gait task difficulty influences dual-task effects on gait speed, especially in older adults. Moreover, the effects of gait task difficulty on dual-task interference appear to be influenced by the difficulty of the cognitive task. Education is an important factor influencing cognitive-motor interference effects on cognition, but not gait

Cognitive-Motor Interference During Functional Mobility After Stroke: State of the Science and Implications for Future Research

Cognitive-motor interference (CMI) is evident when simultaneous performance of a cognitive task and a motor task results in deterioration in performance in one or both of the tasks, relative to performance of each task separately. The purpose of this review is to present a framework for categorizing patterns of CMI and to examine the specific patterns of CMI evident in published studies comparing single-task and dual-task performance of cognitive and motor tasks during gait and balance activities after stroke. We also examine the literature for associations between patterns of CMI and history of falls, as well as evidence for the effects of rehabilitation on CMI after stroke. Overall, this review suggests that during gait activities with an added cognitive task, people with stroke are likely to demonstrate significant decrements in motor performance only (cognitive-related motor interference) or decrements in both motor and cognitive performance (mutual interference). In contrast, patterns of CMI were variable among studies examining balance activities. Comparing people post-stroke with and without a history of falls, patterns and magnitude of CMI were similar for fallers and non-fallers. Longitudinal studies suggest that conventional rehabilitation has minimal effects on CMI during gait or balance activities. However, early phase pilot studies suggest that dual-task interventions may reduce CMI during gait performance in community-dwelling stroke survivors. It is our hope that this innovative and critical examination of the existing literature will highlight the limitations in current experimental designs and inform improvements in the design and reporting of dual-task studies in stroke

Training dual-task walking in community-dwelling adults within 1 year of stroke: A protocol for a single-blind randomized controlled trial

Background: Community ambulation is a highly complex skill requiring the ability to adapt to increased environmental complexity and perform multiple tasks simultaneously. After stroke, individuals demonstrate a diminished ability to perform dual-tasks. Current evidence suggests that conventional rehabilitation does not adequately address gait-related dual-task impairments after stroke, which may be contributing to low levels of participation and physical inactivity in community-dwelling stroke survivors. The objective of this study is to investigate the efficacy of dual-task gait training in community-dwelling adults within 1 year of stroke. Specifically, we will compare the effects of dual-task gait training and single-task gait training on cognitive-motor interference during walking at preferred speed and at fastest comfortable speed (Aim 1), locomotor control during obstacle negotiation (Aim 2), and spontaneous physical activity (Aim 3). Methods/design: This single-blind randomized controlled trial will involve 44 individuals within 12 months of stroke. Following baseline evaluation, participants will be randomly allocated to single- or dual-task gait training. Both groups will receive 12, 30-minute sessions provided one-on-one over 4–6 weeks in an outpatient therapy setting. Single-task gait training involves practice of gait activities incorporating motor relearning principles. Dual-task gait training involves an identical gait training protocol; the critical difference being that the dual-task gait training group will practice the gait activities while simultaneously performing a cognitive task for 75% of the repetitions. Blinded assessors will measure outcomes at baseline, post-intervention, and 6 months after completion of the intervention. The primary outcome measure will be dual-task effects on gait speed and cognition during unobstructed walking. Secondary outcomes include spatiotemporal and kinetic gait parameters during unobstructed single- and dual-task walking at preferred and fastest comfortable walking speeds, gait parameters during high and low obstacle crossing, spontaneous physical activity, executive function, lower extremity motor function, Timed Up and Go, balance self-efficacy, number of falls, and stroke-related disability. Hypotheses for each aim will be tested using an intention-to-treat analysis with repeated measures ANOVA design. Discussion: This trial will provide evidence to help clinicians make decisions about the types of activities to include in rehabilitation to improve dual-task walking after stroke