Step Test 43

The Step Test involves the participant attempting to place his/her foot continuously on and off a 7.5 cm block as quickly as possible, without losing balance, in a 15 second time period.128 The score for each extremity was the number of steps completed in the 15-second period. Scores for each extremity and a total score for both extremities was recorded. The participant completed the test first with the non-paretic foot and then with the paretic foot. Participants who were unable to stand unsupported or who required assistance to place the foot on the step were given a score of 0 for both lower extremities. If the participant completed a number of steps but then required assistance to stabilize the test was stopped and the number of steps completed prior to the loss of balance was recorded. Participants were permitted to wear an orthoses that was being used in therapy for standing and/or walking but, in accordance with published procedures for standardized administration,128 _{were not permitted to use an assistive device during testing. The Step Test has} been shown to be a reliable and valid measure of balance after stroke (test-retest reliability, ICC > 0.88).128

4.   2-minute Walk Test (2MWT)

The 2MWT was used to measure walking capacity over the traditional 6-minute walk test to reduce burden of testing on and minimize fatigue effects for participants during the acute/sub- acute recovery phase.137-139 _{During the 2MWT, the participants were asked to walk as far as}

using their usual assistive device and lower extremity bracing. The standardized course consisted of a looped course requiring occasional partial turns (50-60 degree). The distance walked and number of rest breaks taken were recorded. The 2MWT has reported validity and reliability for this patient population and time post stroke129,139 _{with an inter- and intra-rater ICC = 0.85.}139

Attention-Demanding Task Assessments

Within a median of 2 days (IQR 1, 4) from hospital discharge, the participants were assessed in two attention demanding conditions (obstacle-crossing and dual-task walking). If we were unable to complete both assessments prior to hospital discharge, the assessments were completed within 3 days of hospital discharge. The 3-day limit for assessment was chosen based on the assumption that there would be limited improvement in performance on these measures from hospital discharge to the assessment time point. The assessments were completed in the hospital setting if prior to hospital discharge or at the UNC Interdisciplinary Human Movement Science Research Laboratory when completed post hospital discharge. The attention-demanding task outcome measures were: (1) gait performance and visual scanning behavior during obstacle- crossing and (2) single- and dual-task gait speed and cognition (correct response rate for cognitive task). Vital signs were monitored regularly and testing was paused or discontinued if blood pressure exceeded limits prescribed by the attending physician in hospital or based on recommended values for sub-acute stroke when assessed post discharge.137,138 _{For post discharge} assessments, the assessment began if the resting HR was less than 100 bpm, diastolic BP was less than 100 and systolic BP was less than 180.138 _{This session lasted approximately 60 minutes} including rest breaks. Current evidence supports tolerance for this duration of activity for this patient population at hospital discharge and in the subacute phase of recovery.121 _{At the completion}

of this session the participants were provided either $25.00 or $50.00 to compensate them for their time. During the study, additional funding was acquired resulting in an increase in participant compensation from $25.00 to $50.00. There was no significant difference in recruitment or consent rates between the compensation amounts.

Obstacle-crossing (Aim 1)

For the obstacle-crossing task, participants were asked to walk at their comfortable speed and step over an obstacle (height: 10% of leg length) placed 4.3-m from the start of the instrumented walkway and 5.5-m from gait initiation (Figure 3.2). The obstacle was 91.4 cm in length and 1.3 cm in width. The height of the obstacle was adjusted using wooden blocks ranging from 0.5 to 9 cm in height. We used a high-contrast obstacle (red obstacle on a light-colored walkway) to minimize contrast sensitivity as a potential confounder in the obstacle-crossing performance. The spatiotemporal gait data from the obstacle task from an instrumented walkway (GaitRite® _{or the Zeno™ Walkway) were processed using ProtoKinetics Movement Analysis} Software (PKMAS; Protokinetics, Havertown, PA). The participants were asked to complete four trials of the obstacle-crossing task with the goal of recording a minimum of one obstacle crossing leading with paretic and one with the non-paretic limb. Instructions for the task are provided in Table 3.3. The tester walked alongside the participant to maintain safety during the task, helping only when needed for safety. The participants rested between trials a minimum of 30 seconds to minimize fatigue.

Figure 3.2. Obstacle-crossing task.

Table 3.3. Participant instructions for the obstacle-crossing task

Condition Instructions

Obstacle-crossing “Walk at your comfortable speed and step over the obstacle and

keep walking, trying not to hit it. If you knock over the obstacle, don’t worry; just keep walking to the end of the walkway. If you feel that you cannot step over the obstacle without holding onto something, let me know. I will walk beside you, in case you need assistance.”

Each obstacle-crossing trial was scored as either a "pass" or a "fail". A pass was recorded if the participant ambulated the entire walkway and cleared the obstacle with both limbs without requiring assistance from the tester. A fail was recorded if the participant required assistance from the tester, contacted the obstacle, or failed to step over the obstacle. The obstacle clearance performance was also scored using a 4-item obstacle-crossing error scale. The obstacle-crossing

the obstacle successfully, 2 = lightly contacts the obstacle, does not lose balance, obstacle remains in place, and 3 = knocks obstacle off, or cannot cross without assistance.58 _{The limb that initiated} gait and the lead limb over the obstacle were recorded for each trial. Obstacle-crossing was recorded with one (hospital) or two (laboratory) video cameras positioned to capture the entire walkway and the obstacle-crossing steps. Spatiotemporal parameters of gait were extracted from the instrumented walkway including: (1) pre-obstacle gait speed (m/s), (2) pre-obstacle mean stride length (cm), (3) pre-obstacle mean step length (cm), (4) pre-obstacle step length coefficient of variation (COV, %), (5) pre-obstacle step length asymmetry index (ASI), (6) obstacle-crossing gait speed (m/s), and (7) obstacle-crossing swing duration(s) for lead limb and trailing limb.

Visual scanning behavior was measured using the Natural GazeTM _{Eye Tracking Glasses} (ETG) (Figure 3.3) and analyzed using BeGazeTM _{gaze mapping software (SensoMotoric} Instruments, Boston, MA).140 _{The glasses recorded the environment from the view point of the} participant using a high-definition scene camera at 30 Hz as well as the gaze behavior of the participant (spatial accuracy of 0.1° visual angle ± 0.5° precision) using two infrared cameras aimed at the eyes at 60 Hz onto a Smart Recorder (Samsung Phone). Auditory recordings were taken via the ETG throughout testing to record cues provided by researcher. The ETG were fit to each participant using an adjustable nosepiece (2 sizes) and eye images assessed on the Smart Recorder to ensure appropriate fit and adequate tracking of the pupils. The ETG were calibrated on each participant prior to testing. Corrective lenses were used for anyone requiring correction for visual deficits based on their current eyeglass or contact lens prescription. The Smart Recorder was positioned on the participant while walking using a pocket secured on a belt at the participant’s waist. The primary gaze metric extracted for analysis was the time spent fixating on the obstacle prior to crossing (ms). Additional gaze metrics were extracted including: (1) total time to first

fixation on the obstacle (ms), (2) duration of first fixation on the obstacle (ms), (3) total number of fixations on obstacle (count), and (5) percent dwell time on pre-obstacle walking path, obstacle, and post-obstacle walking path (%).

Figure 3.3. SMI Natural GazeTM _{Eye Tracking Glasses and Smart Recorder eye image.}

Dual-Task Paradigm (Aim 2)

The procedures for the single- and dual-task verbal fluency and walking task represented the classic dual-task paradigm.61,62,141 _{In participants with stroke, gait speed has reported excellent} reliability (ICC=0.80–0.95) under single-task condition and good to excellent reliability (ICC=0.70–0.93) under dual-task conditions.142 _{The verbal fluency task has reported moderate to} good reliability (ICC=0.63–0.81) under single-task condition and moderate reliability (ICC=0.58– 0.75) under dual-task conditions.142

All of trials for the single-task cognitive condition were performed in a seated position. Task order was completed as follows: (1) single-task (ST) walking, (2) ST cognitive (seated), (3) dual-task (DT) walking, and (4) ST walking. The single task walking was completed 2 times (one at start and one at end of all trials. The single task cognitive and dual-task walking conditions were also repeated two times each and the order of testing was randomized. The participants were randomly assigned to 1 of 4 sequences with equal numbers of each sequence for the participant pool. At a minimum, a 30-second seated rest break was given between trials. The single-task and

dual-task walking conditions required the participant to walk at their comfortable speed continuously for 1-minute to ensure sufficient gait and cognitive data were acquired for analysis. The 1-minute trial also ensured that the degree of challenge for the cognitive task was similar for each single and dual-task trial.

The cognitive task for the dual-task paradigm was the category-naming task (e.g., name capital cities in the United States).143 _{The category-naming task was chosen because it most} resembles everyday speech production (e.g., making a shopping list). The task is a rapid and reliable assessment of both verbal ability and executive function, which is important for dual tasking.144 _{The task has face validity as a test of both verbal ability and executive control for which} the person being tested need to retrieve words, focus on the task, select words meeting certain constraints and avoid repetition, which involves executive control processes.144-146 _{Clinical and} neuroimaging evidence suggest that verbal ability may be more strongly reflected in the category naming task especially early in the trial, while later in the trial, executive function, which is necessary to remember what has already been said and to not make any errors (e.g., naming non- category item, or repeating a response).145,147

The category “animals”, which has normative data stratified by age and education,148 _was used to familiarize the participants with the task and to determine the level of difficulty, “easy” or “hard” categories, for the single and dual-task trials (Table 3.4). Distinct categories within the same class of difficulty, “easy” or “hard”, (determined in our previous research, manuscript in

preparation) were used for each single and dual-task trials. Back up categories for both levels of

difficulty were available in case of technical errors requiring a repeated trial or inability of a participant to respond to a particular category (e.g., a color-blind participant who is assigned colors as a category). The participants’ verbal responses during the category-naming task were recorded

using wireless headset (Logitech, Newark, CA) for offline analysis of correct response rate (correct words per minute) and accuracy (correct category, no repetitions).

Table 3.4. Easy, hard, and back-upcategories for four trials of single- and dual-task conditions

Easy Hard

1. Items of furniture/clothing 1. Appliances/other electronics

2. Sports Equipment 2. Canned goods/things that come in a jar 3. Fruits/vegetables 3. Colors

4. Occupations 4. Tools

Back-up Back-up

Cities/states Types of transportation

Countries Building Materials

Things to drink/other liquids Flowers

Things you would see at the beach Birds

Spatiotemporal parameters of gait were collected using an instrumented walkway. For participants tested in the hospital, a portable 5-m walkway was used (GaitRite® _{walkway; CIR} Systems Inc., Franklin, NJ). For participants testing in the laboratory, a 6-m instrumented walkway was used (Zeno™ Walkway; Protokinetics, Havertown, PA) was used. The primary gait parameters extracted using PKMAS (ProtoKinetics, Havertown, PA)149 _{were single and dual-task} gait speed (m/s). Additional gait parameters were extracted as well including stride time, stride time variability, stride length, and cadence. Participants completed continuous passes over the walkway with 1.2-m run on/off at each end, turning off the walkway at each end, so that only steady-state strides were used for analysis. The dual-task conditions were non-priority conditions. Consistent instructions were provided to insure non-priority condition over each of the trials.85 Participant instructions are outlined in Table 3.5. Single and dual-task walking trials were recorded with one (in hospital) or two video (in laboratory) cameras positioned to capture the walkway. The tester walked alongside the participant during the task, helping only when needed for safety.

Table 3.5. Participant instructions for single-task and dual-task walking conditions

Condition Instructions

Single-task category naming (seated) familiarization

“Today you are going to be performing a category naming task in which I’m going to give you a category and ask you to name all the different examples that you can think of from the category in one minute. For instance, if I say holidays, you might say Christmas, Halloween, etc. Do you understand? Can you list two more holidays right now? [HAVE THEM LIST 2 MORE HOLIDAYS AND CORRECT ANY INAPPROPRIATE ANSWERS]. Remember you’ll have one minute, and you should list as many examples as you can without repeating any. You will start listing examples as soon as I tell you the category and tell you to ‘Go.’ Do you have any questions before we start? [PAUSE TO LET THEM ANSWER] For this practice run, your category is animals. Go.”

Single-task category naming (seated)

“You will now do the category naming task while seated. I’m going to give you a new category and ask you to name all the different examples that you can think of from the category that I provide as quickly as you can without repeating any for one minute. You will start listing examples as soon as I tell you the category and tell you to ‘Go’. Ready? Your category is ___. Go”

Single-task walking “When I say Go, you will walk at your comfortable speed for

approximately one minute without stopping. I will tell you when to stop walking. If you reach the end of the walkway area before I tell you to stop, just turn at the blue tape and continue walking back towards where you started. Do you have any questions? Ready? “Go.”

Dual-task walking with category naming

“This time you will walk while performing the category naming task. After I give you the new category and tell you to ‘Go’, you will start walking at your comfortable speed while naming as many items that you can think of from that category without repeating any until I tell you to stop. If you feel that you cannot name any more items for the category you are given, please continue to try. If you reach the end of the walkway before I tell you to stop, just turn at the blue tape and continue walking back towards where you started. Do you have any questions? Ready? Your category is ____“Go.”

Fall and Rehabilitation Diary

At the completion of the baseline assessments, participants were provided a monthly fall and rehabilitation diary and asked to record daily information regarding any falls and rehabilitation

services received over the next 3 months. For the falls diary, the participants recorded daily if they fell, and if so, the number of falls experienced that day and a brief description of the circumstances of the fall(s). A prospective fall diary is the criterion standard for monitoring fall status47 _{and has} been used in a number of studies examining falls post stroke with recommendations for regular follow-ups to maximize recall of circumstances.53,150 _{Participants with the assistance of their} caregiver, family member, and or friend living with them were asked to record the following information for each fall: (1) activity being performed during fall, (2) location of fall, (3) presence and nature of injury, (4) if assistance was required post fall, and (5) if medical attention was sought. A fall was defined to the participant and caregiver(s) as follows: “A fall is when you lose your balance resulting in you landing on the floor or ground or on a lower level due to an uncontrolled, non-purposeful descent. This does not include a fall due to a medical condition (e.g., orthostatic hypotension).” Therefore, falls that occurred due to fainting or loss of consciousness were excluded from analysis. Participants were also provided a rehabilitation diary to record each day for the following 3 months if they attended physical, occupational, and/or speech therapy.

Phone Check-ins

A phone check-in (approximately 20 minutes) was completed every 2 weeks between the baseline and the 3-month follow-up visit to monitor health status, fall history (number, circumstances, injury status, and if medical attention was sought), and frequency of any rehabilitation visits including physical therapy (PT), occupational therapy (OT), and speech therapy (ST) sessions (Appendix 1).

3-Month Post Discharge Follow-up

The 3-month post discharge follow-up took place via a phone interview or in the participant’s home (if within 1 hour of UNC or Duke Hospital). Participants completed a short battery of self-report questionnaires and objective measures of physical activity, and social participation and community re-integration. A 3-month follow-up questionnaire was completed to assess marital status, current living location, geographical area of home, gross household income, number of persons living in home, number of dependents living in home, current driving status, and current employment status. Interview questions were used to verify and/or clarify any details from the falls and rehabilitation diary and phone check-in information.

Physical Activity Measures