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Research Reports |
SL Wolf, PT, PhD, FAPTA, is Director, Division of Research, Professor, Department of Rehabilitation Medicine, and Associate Professor, Department of Anatomy and Cell Biology, Emory School of Medicine, Atlanta, Ga. Address all correspondence to Dr Wolf at Center for Rehabilitation Medicine, 1441 Clifton Rd NE, Atlanta, GA 30322 (USA) (steve{at}spinal.emory.edu)
PA Catlin, PT, EdD, is Professor and Director, Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine
K Gage, K Gurucharri, R Robertson, and K Stephen were students in the Master of Physical Therapy Program, Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, at the time of the study. This study was completed in partial fulfillment of their degree requirements
Submitted November 9, 1998;
Accepted July 20, 1999
 | Abstract |
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.997. Subjects without impairment performed better on all 4 tests than did subjects who had strokes. Increased times on the E-FAP correlated with poor performance on the Berg Balance Test and slow gait speeds on the Timed 10-Meter Walk Test in the subjects who had strokes. The E-FAP scores and the Functional Reach Test scores were not correlated. Conclusion and Discussion. The E-FAP can be administered easily and inexpensively. Because the E-FAP scores differentiated subject groups and correlated with known measures of function, the E-FAP may be a clinically useful measure of ambulation.
Key Words: Ambulation • Balance • Functional assessment • Gait speed • Stroke
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Inevitably, cognition,7 balance,8,9 vision and joint position sense,10 strength,11 speed,12 endurance,13 and adaptability to environmental demands4–6 contribute to successful ambulation. Changes in these variables often are evident in individuals poststroke,14,15 and these changes may be manifested as slow gait speed and altered stance phases16,17 or as compromised ability to regain balance, control movement, or adjust energy expenditure.18 Individuals poststroke may have difficulty adapting to environmental demands, such as rising from a chair, stepping over an obstacle, or ascending stairs.
Measures of gait have been used in both laboratory and clinical settings.19 Laboratory gait analyses may be useful because quantitative measures included in these analyses, such as decreased walking speed and decreased stride length, have been associated with an increased risk of falling.20 Laboratory tests often require electronic equipment, such as electrogoniometers, electrodes, footswitches, computers,21 and video cameras.22 These technical gait analyses may be costly and time-consuming, require extensive training to administer,3, 23 and often do not assess walking across commonly encountered terrains.24 Some more clinically applicable tests of ambulation are easy to administer and require only a stopwatch.25,26 Both laboratory gait analyses and simple tests of gait speed typically do not test the ability to move around obstacles and over different surfaces.
The Functional Ambulation Profile was first described by Nelson,26 who marked the plantar surface of the foot or shoe and recorded foot contact aspects of gait, such as stride length, cadence, and so on. The conceptualization of a functional ambulation profile presented here (ie, the Emory Functional Ambulation Profile [E-FAP]) is quite different and is an inexpensive and easily administered assessment of ambulation. The E-FAP was designed to provide quantitative information about ambulation by measuring time to walk over a standardized array of surfaces and obstacles and accounts for the use of an assistive device. The 5 subtasks in the E-FAP (5-m walks on a floor and on a carpet, an "up & go" task, negotiating an obstacle course, and stair climbing) are included to represent environmental challenges commonly encountered in everyday life.
For the E-FAP to be useful to clinicians, patients, health care decision makers, and third-party payers, reliability and validity of the E-FAP measurements must be established. Subjects who have had strokes are likely to demonstrate altered ambulation14,18 and should exhibit different scores on an ambulation test than subjects without impairment. Therefore, construct validity would be supported if scores on the E-FAP separate subjects who have had strokes from subjects without impairment.
Because no gold standard or criterion measure of ambulation exists, the concurrent validity of the E-FAP will be evaluated by comparing the E-FAP with tests of gait speed and balance. The Timed 10-Meter Walk Test is reported to yield reliable and concurrent, valid measurements of gait speed in patients who have had strokes.17 An increase in gait speed is positively correlated with an improved level of mobility in elderly people.23 Criterion tests of balance include the Berg Balance Test8 and the Functional Reach Test,27 both shown to yield valid measurements of balance in elderly people (Berg Balance Test: subjects' mean age=83 years [SD=6.9]; Functional Reach Test: age range=70–87 years). Good scores on balance scales are positively correlated with high levels of independent mobility in patients poststroke.17 If the E-FAP scores, in turn, are correlated with scores on these tests of gait speed and balance, concurrent validity of the E-FAP measurements would be supported. Furthermore, unlike the other 2 tests, the E-FAP provides information to health care decision makers about how clients ambulate in a variety of environments. These data can be obtained repeatedly during interventions to detect the effectiveness of treatment and to help design home programs. This knowledge is also important in making decisions about the need for caregivers or altering a home environment or for assessing employment opportunities.
The reliability and validity of the E-FAP component measures should be assessed before the tool can be applied to assess the benefit of interventions to improve walking. Therefore, the research questions under consideration were: (1) Does the E-FAP differentiate between subjects who have had strokes and subjects without impairment? and (2) Is the E-FAP correlated with previously validated measures of walking speed and balance?
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All subjects participating in the study provided written informed consent. The personal physician of each subject with a stroke approved his or her participation in the study.
Measurements and Instrumentation
Emory Functional Ambulation Profile.
Five subtasks comprise the E-FAP: (1) a 5-m walk on the hard-surfaced floor, (2) a 5-m walk on the carpeted floor, (3) performance of an "up & go" task, (4) negotiation of an obstacle course, and (5) ascent and descent of 4 stairs.28 Subtasks were completed in the above sequence according to a standardized protocol (Appendix). The number of seconds taken to complete each subtask was recorded. The time to complete each subtask was multiplied by a factor corresponding to the level of assistive device used (Figure). Inclusion of the assistance factor as part of the E-FAP serves several purposes. First, this inclusion allows the score to reflect differences in the amount of assistance required by an individual. The assistance factor increases relative to the amount of support offered by the assistance device. Second, use of an assistance factor permits differentiation of individuals who are walking at the same speed but with different assistive devices. Moreover, the assistance factor can reflect changes in gait speed as patients progress from one device to another. Third, use of the assistance factor offers a clinically descriptive picture for other health care professionals to interpret the E-FAP. The 5 subtask scores were summed to yield an E-FAP total score. For each subject with a stroke, an E-FAP total score also was computed without the multiplication factor for assistive device. Thus, calculations were made for all subjects with strokes using both an assistance factor and no assistance factor.
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Berg Balance Test.
The Berg Balance Test was administered to each subject according to the standard protocol.30 The Berg Balance Test consists of 14 tasks performed in the following sequence: (1) sit to stand, (2) stand unsupported, (3) sit with back unsupported, (4) stand to sit, (5) transfer, (6) stand with eyes closed, (7) stand with feet together, (8) reach forward with an outstretched arm, (9) retrieve object from floor, (10) turn to look behind, (11) turn 360 degrees, (12) place alternate foot on stool, (13) stand with one foot in front of the other foot, (14) stand on one foot. Performance of each task was scored on a scale from 0 to 4, with 0 representing minimal completion of the task and 4 representing full completion of the task according to test criteria. A total score of 56 represents perfect performance.
Functional Reach Test.
The score on the Functional Reach Test was the distance (in centimeters) of the subject's reach as determined by the total excursion of the subject's third metacarpal in the nonhemiparetic arm of the subjects with strokes or the dominant arm of the subjects without impairment.27 Each subject was instructed to flex the test arm forward to 90 degrees and then reach forward as far as possible without taking a step. One practice trial was performed followed by 3 separate test measurements. The average of the 3 measurements was the subject's final score. With the exception of an AFO, use of assistive devices for subjects with strokes was not allowed during this test.
Leg length was measured bilaterally (in centimeters) for each subject.31 Each subject assumed a supine position on the treatment table with anterior superior iliac spines (ASISs) and medial malleoli exposed. Following palpation of the superior aspect of the ASIS, the tip of the tape measure was placed on this landmark. Next, the most prominent point on the medial malleoli was palpated, and the tape measure was extended to this landmark and leg length was then measured.
Each subject self-reported age and gender information, and this information was verified by inspection of legal identification (eg, driver's license). Information about time since onset of stroke and side of lesion was obtained by self-report or medical chart review. The height of each subject was measured by having each subject remove his or her shoes and stand upright against a wall marked in inches. Measurement was recorded in inches and later converted to centimeters.
Joint position sense was assessed bilaterally for each subject at the following joints: shoulder, hip, knee, and ankle.31 Each subject was instructed to keep his or her eyes open while the extreme positions of "bent" and "straight" were demonstrated for each joint. Next, the subject was asked to close his or her eyes while the investigator grasped the limb and moved the joint passively into one of the extreme positions. The subject was asked to identify the position of the joint as bent or straight, and the investigator recorded joint position sense as "intact" if the subject correctly identified the position of the joint or "not intact" if the subject's response was incorrect.
Prior to test administration, blood pressure was assessed using a sphygmomanometer and stethoscope on the brachial artery.31 Any subject with a resting blood pressure greater than 170/100 mm Hg was excluded from the study.32 Pulse rate was measured (in beats per minute [bpm]) by palpation of the radial artery and timed with digital watches.31 Any subject with a resting heart rate greater than 100 bpm was excluded from the study.32 One subject was excluded from the study because of high blood pressure. A physician examined that subject. All other subjects met the blood pressure and heart rate criteria before or after the testing session.
Identical digital, manual stopwatches with readings to 1/100 of a second were used to measure performance time on all timed tests. Digital stopwatches were calibrated manually to 1/10 of a second prior to and throughout data collection. Interrater agreement was determined for leg length, joint position sense, and subject characteristics (ie, gender, age, height) by repeated observations of 2 investigators. To establish reliability between investigators prior to data collection, agreement between the investigators was obtained over 4 trials. Agreement was defined as exact for subject characteristics and less than or equal to one-half standard deviation of data reported in previous studies, as follows: Timed 10-Meter Walk Test=±2.9 seconds,12 Berg Balance Test total score=±2.9,30 Functional Reach Test=±1.9 in*,33 E-FAP total score=±2.9 seconds (based on Timed 10-Meter Walk Test data), leg length=±1.0 cm,31 and joint position sense=exact. Two investigators scored each of the 4 tests concurrently throughout the study in order to assess interrater reliability at the conclusion of the study.
Procedure
Two of 4 investigators were randomly assigned to each subject for a data collection session. The investigators initially contacted and interviewed each subject by telephone or in person to assess qualification for the study. Each subject was asked to wear comfortable walking shoes to the 1-hour data collection session. At the start of the data collection session, each subject answered a questionnaire to ensure qualification. One investigator took preliminary measurements, including blood pressure, pulse rate, height, joint position sense, and leg length. The 4 tests (E-FAP, Timed 10-Meter Walk Test, Berg Balance Test, and Functional Reach Test) were administered in random order for each subject. For example, the first subject received the following sequence: the Berg Balance Test (subject completed all 14 items in sequence), the Timed 10-Meter Walk Test, the E-FAP (subject completed all 5 subtasks in sequence), and the Functional Reach Test. Each subject was offered a 2-minute rest period between tests, if needed. Otherwise, each subject progressed immediately to the next test. For each test, one investigator demonstrated the test and gave specific instructions to the subject. A second investigator guarded the subject during each task. Each investigator independently recorded performance data on a separate data collection form.
On completion of the data collection session, one investigator remeasured the subject's blood pressure and pulse rate. If blood pressure exceeded 170/100 mm Hg or the pulse rate exceeded 100 bpm, the subject was asked to remain seated for 5 minutes, and blood pressure and pulse rate were reassessed. If blood pressure or pulse rate did not descend, a physician was contacted. The subject was dismissed at the conclusion of the data collection session when blood pressure and pulse rate values were below 170/100 mm Hg and 100 bpm, respectively.
Data Analysis
The mean, standard deviation, and minimum and maximum values were determined for each test score, age, height, and leg length per group and for time since onset of stroke in the subjects with strokes. Gender in both groups and side of lesion in the subjects with strokes were summarized as frequency of occurrence. Measurements obtained by the primary researcher were used in all analyses except determination of interrater reliability.
All test scores and leg-length measurements were interval data, except scores from the Berg Balance Test, which were ordinal data. Normality of distribution and homogeneity of variance for each test score and leg-length measurement were tested using the Walled test and the Sphericity test, respectively. In the subjects without impairment, data meeting these assumptions included the E-FAP total score and scores for the floor, up & go, obstacles, and stairs subtasks. Their scores on the Functional Reach Test, the Timed 10-Meter Walk Test, and the leg-length measure also met these assumptions. Scores on the Functional Reach Test, the Timed 10-Meter Walk Test, and the leg-length measure met these assumptions in the subjects with strokes. If data did not meet an assumption, parametric test results are reported only when the nonparametric tests yielded identical results. Otherwise, nonparametric test results are identified.
The agreement between raters' scores on the E-FAP, the Timed 10-Meter Walk Test, the Berg Balance Test, the Functional Reach Test, each subtask of the E-FAP, and the leg-length measure were analyzed using a nested random-effects analysis of variance (ANOVA) to calculate the intraclass correlation coefficient (ICC[2,1]).34 The E-FAP total score and scores on the Timed 10-Meter Walk Test, the Berg Balance Test, and the Functional Reach Test were compared between groups and tested using an unpaired t test per variable. The differences between times on subtasks of the E-FAP (floor, carpet, up & go, obstacles, stairs) were compared within each group using a Friedman ANOVA by ranks and a Tukey Honestly Significant Difference post hoc test. The difference in scores on each subtask of the E-FAP between groups was tested using a Wilcoxon rank sum test with a Bonferroni adjustment. The relationship between the E-FAP total score and scores on the Timed 10-Meter Walk Test, the Berg Balance Test, and the Functional Reach Test was tested using a Pearson product-moment correlation coefficient or a Spearman rank correlation. The correlation between average leg length and scores on the Timed 10-Meter Walk Test for each group and for both groups combined was determined using the Pearson product-moment correlation coefficient.
For all statistical tests, the alpha level was <.05 and the power was .90. Power was based on effect size of a 10% difference between subtasks and between groups. Effect size was based on previously collected E-FAP data from the Program in Restorative Neurology at the Emory Clinic, Atlanta, Ga, on subjects with strokes. To obtain a power of .90, data were collected on 28 subjects without impairment and 28 subjects with strokes.
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The E-FAP subtask scores varied within each group (P<.0001, Friedman 2-way ANOVA by ranks). Among the subjects without impairment, floor and carpet subtask scores were not different; however, floor and carpet subtask scores were lower than stairs subtask scores. Up & go subtask scores were lower than obstacles subtask scores for the subjects without impairment (Tabs. 2 and 4). The pattern of differences among subtasks was the same in the subjects with strokes as in the subjects without impairment, with the following exceptions: stairs subtask scores equaled floor subtask scores for the subjects with strokes with an assistance factor, and stairs subtask scores equaled up & go subtask scores for the subjects with strokes without an assistance factor.
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The relationships among test scores are presented in Table 5. In the subjects with strokes, E-FAP scores with and without an assistance factor were negatively related to the Timed 10-Meter Walk Test scores (P<.0001) and the Berg Balance Test scores (P<.0009); that is, slow times on the E-FAP correlated with slow gait speeds and poor balance. The E-FAP scores were not related (P>.05) to Functional Reach Test scores in the subjects with strokes. The Berg Balance Test scores were positively related to the Timed 10-Meter Walk Test scores (P<.0004, Tab. 5) and to the Functional Reach Test scores (P<.0004, Tab. 5) in the subjects with strokes. In the subjects without impairment, E-FAP scores were negatively related (P<.0001) to Timed 10-Meter Walk Test scores but were not related to Berg Balance Test scores or Functional Reach Test scores (P>.05).
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| Discussion |
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Limitations of this study were the relatively small number of subjects and the inclusion of only subjects with strokes and subjects without impairment. In addition, all levels of mobility were not represented, because subjects were required to ambulate without the assistance of another person. In the subjects with strokes, however, nearly equal distribution of right- and left-sided lesions and the wide range of times since onset of stroke increased the representation of people with strokes.
The E-FAP may be used to differentiate between subjects based on differences in functional ambulation. The scores of the subjects with strokes on the other 3 tests were poorer than were the scores of the subjects without impairment, indicating function is decreased in people who have had a stroke. Gait deficiencies in the subjects with strokes may be indicated by dependency on assistive devices. Eighteen subjects with strokes required assistive devices for ambulation. The E-FAP scores were different between groups both with and without an assistance factor, suggesting the difference between scores was not obtained artificially by including an assistance factor in the subjects with strokes.
For purposes of clinical application, ordering of subtasks according to increasing time to complete each subtask may be desirable. As a result, subtasks that potentially place high demands on endurance are not encountered at the beginning of the test, and the maximum number of subtasks can be completed before fatigue limits further participation. In contrast, subtasks requiring the most time to complete may be ordered first, before fatigue is an issue. In either case, the order of subtasks according to increasing time may be of interest in future revision and development of the E-FAP. Subtask order difference between groups according to increasing time may suggest that subjects with strokes responded differently to subtask demands in comparison with subjects without impairment.
Concurrent validity of the E-FAP is supported by correlation of the E-FAP scores with scores on the Timed 10-Meter Walk Test and the Berg Balance Test. The Timed 10-Meter Walk Test scores and the E-FAP scores were correlated in both groups possibly because each test measures walking speed. However, the E-FAP measures gait speed in various environmental conditions versus solely across a standard, hard-surfaced floor. Gait speed has been correlated with other clinical tests of function, including the Fugl-Meyer Test, Barthel Index, and Berg Balance Test.17 The Berg Balance Test and the E-FAP may correlate because both involve multiple tasks requiring balance, strength, and endurance. The Berg Balance Test has previously been correlated with level of independent mobility.8 Therefore, because the E-FAP correlates with the Timed 10-Meter Walk Test and the Berg Balance Test, E-FAP performance also may reflect function.
The E-FAP and the Functional Reach Test did not correlate in either group because the Functional Reach Test measures a person's stability during performance of a single task, whereas the E-FAP is designed to incorporate multiple tasks that an individual might encounter during everyday functioning. Weiner et al33 indicate the Functional Reach Test seems less influenced by strength and endurance and, instead, represents a more "pure" balance measure. This measure may be influenced by limitations in shoulder or intervertebral mobility. The E-FAP and the Berg Balance Test, however, each incorporate measures of balance, strength, and endurance during multiple functional activities.
In the subjects with strokes, the Functional Reach Test may have correlated with the Berg Balance Test because both tests measure an element of balance, which the E-FAP is not sensitive to in this specific group. The Functional Reach Test is one of the 14 tasks included in the Berg Balance Test; thus, a correlation between the 2 tests could be expected. The E-FAP, the Berg Balance Test, and the Functional Reach Test seem to be related based on relative dynamic challenges to balance. Although the Functional Reach Test involves a relatively less dynamic task, the Berg Balance Test incorporates a continuum of balance challenges ranging from less dynamic to more dynamic.
The E-FAP score correlation with scores of the other 3 tests in the group without impairment is of interest because these analyses may reveal information about the E-FAP's ability to detect differences in subjects with high levels of function, a consideration as patients' function improves. In individuals without impairment, the E-FAP may not correlate with the Berg Balance Test because scores on the Berg Balance Test are ordinal data, whereas E-FAP scores are interval data and, thus, are more sensitive. Richards et al17 found that the Berg Balance Test is not as sensitive in subjects with faster walking speeds in comparison with slower walkers. Furthermore, Berg et al30 suggest the utility of the Berg Balance Test is limited in active people with minimal balance deficits.
Clinical Implications
In the current health care environment, decisions regarding reimbursement for patient care often are made by a variety of individuals, many of whom have not had clinical training. Consequently, meaningful tests should be concise, efficient, simple, and easy to comprehend by a number of health care decision makers. They must be also interpreted easily by health care professionals and individuals authorized to decide on reimbursement for services. The E-FAP may meet these criteria. The E-FAP requires minimal equipment and can be administered fairly quickly. The test can be administered in most settings by clinicians or personnel under their supervision. If further research supports the predictive validity of the E-FAP, health care professionals can use the subtasks from the E-FAP to determine whether a patient is ready to return to home-based ambulatory activities by assessing data from the individual subtasks. In addition, improvements can be seen over different conditions when administered more than once.
Future Studies
The E-FAP measures may be clinically useful because reliability, construct validity, and concurrent validity were supported in this study for people with strokes. Additional studies, however, are necessary to establish the validity of the E-FAP. Currently, the E-FAP cannot be used to assess a patient requiring any manual assistance from another person. Therefore, future development of the E-FAP will consider methods to account for patients requiring manual assistance. The sensitivity of the E-FAP to patient progress in rehabilitation over time or over other surfaces or inclines also should be investigated. Finally, additional research studies are needed to establish the reliability and validity of E-FAP measures in other subject populations.
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| Footnotes |
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This study was approved by the Human Investigations Committee at the Emory University School of Medicine.
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