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Research Reports |
MF Levin, PT, PhD, MOPPQ, is Associate Professor, School of Rehabilitation, University of Montreal, and Center for Interdisciplinary Research in Rehabilitation, Rehabilitation Institute of Montreal, 6300 Darlington, Montreal, Quebec, Canada H3S 2J4 (levinm{at}poste.umontreal.ca).
J Desrosiers, OT, PhD, is Associate Professor, Faculty of Medicine, University of Sherbrooke, and Researcher, Research Centre on Aging, Sherbrooke Geriatric University Institute, Quebec, Canada
D Beauchemin, PT, MOPPQ, is Physiotherapist, Rehabilitation Institute of Montreal
N Bergeron, PT, MOPPQ, is Physiotherapist, Rehabilitation Institute of Montreal
A Rochette, OT, MSc, is Research Assistant, Research Centre on Aging, Sherbrooke Geriatric University Institute
Address all correspondence to Dr Levin
Submitted November 21, 2002;
Accepted July 10, 2003
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Key Words: Compensatory strategies • Hemiparesis • Reaching performance • Validation
| Introduction |
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 TopAbstract Introduction MethodResultsDiscussion and ConclusionsAppendixReferences |
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Recent advances in our understanding of the potential for neuronal recovery after stroke-related brain damage has led to the development of new interventions aimed at maximizing recovery such as "task-oriented" therapy and "constraint" therapy.5,12,13 In the task-oriented approach, patients participate in intensive therapy sessions in which arm reaching behavior may be improved by practice of "lost" motor elements—an approach known as "practice of missing elements" or "shaping." In "shaping," for example, a desired motor task is approached in small steps in which specific joint movements and movement combinations are practiced.14 The identification and quantification of compensatory movements used for reaching is an essential step in the development of task-oriented or shaping intervention approaches,5,15 yet no scales currently exist that specifically identify "healthy" movement patterns and compensatory movements during a reaching task.
The World Health Organization has developed a common language for guiding research and clinical practice related to disability known as the International Classification of Functioning, Disability and Health (ICFDH).16 Three levels related to human functioning have been identified: functioning at the level of the body or body part (impairment), functioning at the level of the whole person (activity limitations), and functioning at the level of the whole person in a social context (participation restrictions). According to this classification, impairments are problems in body function or structure such as a clinically meaningful deviation or loss. Activity limitations (formerly termed "disability") are described as difficulties that an individual may have in performing activities.
The measurement of the performance of the affected arm and hand of patients with hemiparesis is important for determining the goals of intervention as well as the outcomes of rehabilitation. Within the task-oriented model, there are 3 levels of performance of interest to clinicians.15,17 One level is functional ability and is related to activity according to the ICFDH classification. The other 2 levels are related to impairment and concern movement strategies used to accomplish a task and sensorimotor impairments.
Functional outcome scales assess the performance of activities of daily living at the activity level and quantify whether a task is performed within the constraints specified by the test (eg, Frenchay Arm Test,18 Barthel Index19) while little attention is paid to how the movement is performed. At the other extreme are tests designed to assess underlying impairments (impairment scales) such as decreased range of motion or muscle weakness or how well specific movements are performed. The latter tests evaluate movements or movement patterns having no functional goal (for example, see Gowland et al,20 Fugl-Meyer et al,21 and Brunnström22). Such impairment scales identify the factors that may affect the performance of a task. It may be more useful for clinicians to have a scale that measures the quality of motor performance specific to the task that identifies which elements of that task are missing (ie, range of angular movement and combinations of movements) and how they are compensated. This is especially important in light of the increasing interest in therapeutic techniques emphasizing practice of lost motor elements such as "task-oriented training" or "shaping" used in constraint-induced therapy.5,13,14 Therapists may then be able to use this information to design intervention programs for retraining lost motor components and to decrease maladaptive compensatory movements. Indeed, because there are few impairment scales that are based on movement analysis and that detail the extent and patterns of joint participation required for a task, it has been difficult to relate quality of movement to function. The lack of a clear relationship between quality and function is partly due to the lack of good measures.
There are several other reasons underlying the need for the development of such measures. One reason is the need for a tool to identify missing elements of a task and to track recovery. Another reason may be to provide evidence that "healthy" movement patterns can recover, rejecting the notion that the only role of physical therapy is to teach patients with neurological deficits how to compensate for lost motor functions (see Levin8 and Latash and Anson23). The development of such scales may be a first step in this process.
The purpose of this article is to describe a newly developed impairment scale—the Reaching Performance Scale (RPS)—for the identification and quantification of movement patterns and their compensations during reach-to-grasp tasks in patients with upper-extremity hemiparesis secondary to a stroke. This scale particularly focuses on compensatory movements used during the transport phase of reaching, defined as the beginning of the movement until the object is grasped. The scale also includes a measure of compensatory strategies used for grasping (eg, winding fingers around a cone, downward grasping) previously described by Roby-Brami et al.24 Only the grasping strategy (eg, winding fingers around a cone, downward grasping) and not other aspects of grasping (eg, hand orientation, grip force, release) are assessed with the RPS because many other clinical scales exist that specifically address grasping at the impairment, functional, and disability levels.25–27 Thus, in our study the purpose of the scale was to identify and quantify the degree of motor compensations used by patients when reaching to grasp an object placed within the reach of the arm (task 1) and beyond the reach of the arm (task 2). The 2 different tasks were used because movement analysis studies3,28 have shown that the transport requirements of the arm when grasping objects located close to and far from the body are different. For example, successful grasping of an object placed close to the body requires the shoulder and elbow to be positioned so that the hand is oriented frontally, whereas grasping a target placed far from the body requires hand opening when the proximal joints act to orient the hand more sagittally. This article will enumerate the steps taken for the development of the RPS, the determination of its content, and the testing of concurrent and discriminant validity and the preliminary intrarater and interrater reliability of data obtained with the RPS.
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Phase 1: Development of the Scale and Determination of Content Validity
In this phase, the task components to be included in the scale were determined and a 4-item assessment scale was created for each component. The task components were chosen based on the results of recent detailed kinematic studies of reaching and grasping in patients with stroke.2–4,24 These studies showed that patients with stroke used excessive anterior trunk displacement (>4.5 times the amount used by people without motor impairments) to compensate for mean decreases of around 25% in the active range of elbow extension and more than 50% in the range of active shoulder flexion even when reaching to targets placed within the length of the arm.3 The amount of excessive trunk displacement varied with the severity of the hemiparesis in the arm and hand. Measurements of trunk displacement were inversely correlated with Fugl-Meyer Assessment of Sensorimotor Recovery After Stroke scores, where lower scores indicate greater impairment (r=.87), and directly correlated with the degree of spasticity in the elbow flexors as measured with the Composite Spasticity Index29 (r=.75). The amount of trunk displacement also was associated with a lower range of motion during elbow and shoulder movements and with a disrupted interjoint coordination between elbow and shoulder movements.2
Two consensus meetings were held in which the tasks to be included in the scale and the task components to be evaluated were decided upon. Participants in the consensus meetings were 3 physical therapists, 3 occupational therapists, and 2 rehabilitation researchers (1 physical therapist, 1 occupational therapist). All participants had experience with the management of patients with neurological problems and worked in subacute rehabilitation centers. The meetings focused on discussions of the relevance of the scale to rehabilitation goals, the clarity of the description of each component of the scale, and the appropriateness of each task to be included in the scale. Identification of the components of the task to be included in the scale was based on the results of the movement analysis and the clinical experience of the participants. The meetings also served to decide upon a preliminary rating scale for each task component.
The reaching task.
The participant was seated in a chair with a seat height of 42 cm and with a backrest but no armrests while facing a table with a height of 72 cm. A standard-height chair instead of an adjustable-height chair was used to better replicate the type of chair found in the clinic. The chair was placed at a distance equal to the length of the participant's fully extended arm so that the distal crease of the wrist was aligned with a mark placed 4 cm from the front edge of the table. The participant sat up without leaning on the back support of the chair and with both feet placed flat on the floor. Initially, both arms were held alongside the body and were not supported on either the table or the participant's lap. The task involved reaching and grasping a cardboard cone (7-cm base, 17.5 cm high) placed on the table in the midline of the trunk, 1 cm (close target) or 30 cm (far target) from the front edge of the table. Only the reach-to-grasp component of the task and not the transport of the cone after grasping was assessed because the scale was designed to be an impairment scale assessing the impairment of reaching and not the functional disability associated with object manipulation. A cardboard cone with a rough surface was used. The high-friction surface of the cone allowed patients with even low levels of motor recovery of the hand (gross grasping only) to perform the task. For the close target, the cone was placed so that it could easily be grasped with the arm flexed and did not require trunk anterior displacement in individuals without motor impairments. In contrast, reaching the far target required anterior trunk displacement of about 25% of the reaching distance between the initial hand position and the cone for successful reaching and grasping.15 Both tasks primarily involved elbow flexion at the beginning of the reach followed by combined shoulder flexion, shoulder horizontal adduction, and elbow extension during the middle and latter phases of the reach.
Based on our movement analysis (see Cirstea and Levin,2 Michaelsen et al,3 and Levin et al4), 7 movement components were included in the preliminary version of the scale: (1) speed of movement, (2) trunk displacement, (3) movement smoothness or fluidity, (4) shoulder movements, (5) elbow movements, (6) prehension, and (7) global score. A smooth or fluid movement was defined as a movement that occurred without tremor-like jerkiness visible at the hand throughout the reach (ie, the hand traced a smooth path throughout the reach and did not reverse direction or move in directions other than toward the target). The same rating scale for both the near task (task 1) and the far task (task 2) was used for components 1, 3, 6, and 7. For components 2, 4, and 5, different scales were used for each task because, for task 1, better scores indicated that the participant did not use trunk displacement (component 2) or shoulder protraction (component 4) and that most of the displacement of the hand toward the object was accomplished by elbow extension (component 5). For task 2, however, better scores indicated that there was forward trunk movement (component 2) and shoulder protraction (component 4) combined with complete elbow extension (component 5). Based on our kinematic analysis of task 2,3 trunk displacement was considered adequate if, at the time of grasping, the elbow of the reaching arm was almost fully extended. If trunk displacement was excessive, the elbow would have remained flexed, and, if trunk displacement was inadequate, the patient would not be able to bring the hand in close enough proximity to the object for it to be grasped.
The preliminary version of the scale was used to assess reaching movements in 10 individuals with hemiparesis due to stroke from the Sherbrooke Geriatric University Institute and the Rehabilitation Institute of Montreal. We used a convenience sample of participants recruited from lists of patients who had been discharged from inpatient rehabilitation units. The participants were 6 men and 4 women with a mean age of 66.2 years (SD=9.3) who had sustained a stroke between 2 and 5.5 years earlier. Their scores on the Chedoke-McMaster Stroke Assessment20 ranged from 3 to 7 for the arm (
=4.9, SD=1.8) and from 2 to 7 for the hand (=4.9, SD=1.7). For a description of this scale, see the "Concurrent Validity" section. Each participant was informed of the nature of the study and signed a consent form approved by local hospital ethics committees.
With the participant's consent, his or her performance was videotaped for subsequent analysis. The camera was placed at a 45-degree angle between the frontal and sagittal planes on the side of the hemiparetic arm. Each participant was allowed 2 practice trials for each task and was then videotaped as each task was performed 3 times. The videotapes were viewed by 2 groups of 6 physical therapists and occupational therapists at the 2 hospital centers. These 2 groups, together with the investigators at each center, formed the expert panel that examined the content of the rating scale and that suggested changes or refinements to the wording of the scale. At this stage, the consensus of the expert panel was that the first component, movement speed, should be deleted because movement time measures a different dimension of performance that does not directly relate to motor compensation. Indeed, as movement analysis studies2,3 have shown, the presence of compensatory movements during reaching is often accompanied by a decrease in movement time. Because the presence of compensations may lead to a shorter movement time (or an increase in movement speed), the inclusion of this component in the scale would lead to paradoxical results. In addition, our preliminary analysis showed that movement time was prolonged in almost all patients and varied widely among patients (2–4 times slower than in people without motor impairments), making this item difficult to score. Finally, in this phase of the scale development process, some of the wording describing the item scores was clarified.
The RPS.
In its final form, the RPS scale evaluates 6 components. Four components are related to reaching close and far targets: trunk displacement, movement smoothness, shoulder movements, and elbow movements. The 2 additional components globally rate the quality of prehension and the accomplishment of the task (see Appendix). The focus of each item is separate. The therapist is asked to decompose the reaching movement into its elements visually (trunk displacement, movement smoothness, shoulder displacement, elbow displacement, and quality of prehension) even though the elements are changing together.
The first component, trunk displacement, rates to what extent trunk movement is used to reach the close and far targets. Trunk displacement may include trunk flexion, trunk rotation, or flexion accompanied by rotation). However, the major component contributing to the displacement of the hand during forward reaching is forward displacement of the trunk. The highest rating of 3 is given if no compensatory anterior trunk displacement is used for reaches to the close target and an amount of trunk displacement proportional to the distance reached (approximately 25%) is accompanied by almost full extension of the elbow for reaches to the far target.
For the second component, movement smoothness, movement is considered smooth if alternating, misdirected, or sequential arm and trunk movements do not occur when extending the hand to the target. The evaluator must discriminate between movement jerkiness and the presence of trembling or dysmetria.
The third component, shoulder movements, rates whether adequate flexion and horizontal adduction of the shoulder is present. Adequate flexion consists of approximately 20 degrees for the near target and 40 degrees for the far target, while approximately 40 degrees of shoulder adduction is required for each target to bring the arm to the sagittal midline.2,4 Poorer performance is noted if compensatory scapular elevation is used to increase shoulder flexion or shoulder horizontal adduction is decreased.
For the fourth component, elbow movements, the highest rating of 3 is given if adequate elbow extension is produced to reach the target. Lower scores are given if the participant is unable to use, or uses less than adequate, elbow extension to move the hand to the target. Approximately 80 and 100 degrees of elbow extension is required for the near and far targets, respectively.4 A description of the scaling is given in the Appendix.
For the 2 global ratings, highest scores are given for accomplishment of the task without the use of compensatory strategies. For component 5, prehension, "task accomplishment" implies adequate hand opening and closing. For component 6, global score, "task accomplishment" implies the production of a smooth and direct movement. Although component 6 may be related to the first 5 components, our purpose was to have an idea of the successful accomplishment of the task itself and the global quality of the movement. Scores on items 1 to 5 can be used to identify deficits in specific aspects of the movement, and scores on each item together with item 6 (global score) can be summed for a total score of reaching performance ranging from 0 to 18.
Phase 2: Validity and Reliability Studies
Once the final version of the scale was produced, validity and preliminary reliability studies were initiated with a convenience sample of participants. Potential participants were identified from a pool of individuals who had previously participated in research studies in the 2 centers over the past 2 years. All individuals were no longer undergoing inpatient or outpatient therapy. They were contacted until the target number was obtained per center. Twenty-eight individuals met the inclusion criteria and gave written consent. No further demographic or clinical information was gathered on the nonparticipants. Thus, how they may have differed from those who participated is not known. Fifteen participants were from the Sherbrooke Geriatric University Institute, and 13 participants were from the Rehabilitation Institute of Montreal. They were videotaped while performing the 2 tasks. Individuals with hemiparesis were included in the study if: (1) they had sustained a single cerebrovascular accident (CVA) of hemorrhagic or ischemic etiology, (2) they had given their informed consent, (3) they had good cognitive functions, and (4) their ability to reach with the hemiparetic arm was rated 2 or better on the arm and the hand sections of the Chedoke-McMaster Stroke Assessment. "Good cognitive function" was determined by the judgment of the clinical evaluators. The only criterion was that the participant could understand his or her involvement in the study and the task to be accomplished. Side of CVA, age, hand dominance, and the time since stroke were described but were not considered in the selection procedure. Participants whose hemiparesis was due to trauma were not included in the study because of the more global nature of the head injury. Demographic and clinical data for each participant are provided in Table 1.
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The Chedoke-McMaster Stroke Assessment20 was used to rate motor performance of the arm and hand on categorical scales. This assessment has demonstrated both validity (construct, concurrent) and reliability (test-retest, intrarater, and interrater).20 With this test instrument, participants must complete 2 of 3 tasks outlined for each level without assistance to obtain a grade from 1 (eg, no function) to 7 (eg, normal function). Two separate scales are used to rate hand and arm motor performance. For example, the 3 tasks to obtain a grade of 2 on the arm section are: (1) the examiner should feel resistance to passive shoulder abduction or elbow extension, (2) the patient should be able to actively extend the elbow when some facilitation procedure is applied, and (3) the patient should be able to actively flex the elbow when some facilitation procedure is applied. To obtain a grade of 7, the patient should be able to: (1) clap his or her hands overhead, then behind the back, 3 times in 5 seconds; (2) perform scissoring movements of the arms in 5 seconds with the shoulders initially at 90 degrees of forward flexion; and (3) perform resisted shoulder lateral (external) rotation with the arm alongside the body and the elbow flexed to 90 degrees.
For the second evaluation, we used the TEMPA, a functional test evaluating the capacity to perform a total of 4 unimanual activities (pick up and move a jar, pick up a pitcher and pour water into a glass, handle coins, and pick up and move small objects) and 5 bimanual activities27 (open a jar and remove a spoonful of coffee, unlock a lock and open a pill container, write on an envelope and stick a stamp on it, tie a scarf around one's neck, and shuffle and deal cards). Consideration of how bilateral tasks are performed assesses how a person compensates for the impairment or disability of the affected upper limb with the less affected upper limb. In this test, the performance on each task was measured using a 4-level scale: a score of 0 indicates that the task is successfully completed, without hesitation or difficulty, as instructed or demonstrated; a score of 1 denotes that the task is performed completely, but with some hesitation or difficulty; a score of 2 is given if the task is partially completed (more than 25%) or certain steps are done with major difficulties, necessitating repeated efforts; and a score of 3 indicates that less than 25% of the task can be performed. The total score is determined by adding scores obtained in unilateral and bilateral tasks. The lower the score, the better the performance. Thus, a score of 0 indicates normal performance, and a score of 27 indicates complete inability to perform the tasks. Test-retest and interrater reliability studies have confirmed good stability of the test over time (intraclass correlation coefficients [ICC]=.70–1.00) and satisfactory agreement between different examiners (ICC=.75–1.00).31 In addition, the TEMPA has been found to yield scores with concomitant criteria and construct validity.32
Grip force was measured (in kilograms) using a Jamar dynamometer* with the arm alongside the body and the elbow at 90 degrees of flexion.30 The measurement used was the mean of 3 trials in which the patient was encouraged to produce maximum voluntary contraction forces of the hand as recommended by the American Society for Surgery of the Hand and the American Society of Hand Therapists.33
Discriminant validity.
A discriminant validity study was done to determine if participants' scores obtained with the RPS differed according to the level of impairment (slight [6–7], moderate [4–5] or severe [2–3]) as measured with the Chedoke-McMaster Stroke Assessment. To determine the level of impairment, the lower of the arm and hand scores on the Chedoke-McMaster Stroke Assessment was used.
Preliminary intrarater and interrater reliability.
In order to have preliminary data on reliability prior to carrying out a more comprehensive reliability study, we asked a small convenience sample of 3 physical therapists from the Rehabilitation Institute of Montreal to rate the scale components from videotapes made of the participants from the Rehabilitation Institute of Montreal (n=13). The raters were clinicians who were not involved in the kinematic studies of reaching and did not participate in the test development process or in the study in any other way. The 3 raters viewed the videotapes individually and rated the 6 components on the 4-point scales. Rater 1 had some experience (<1 year) assessing patients with neurological problems, rater 2 had moderate experience (2–5 years), and rater 3 had extensive experience (>10 years). Two of the raters (raters 2 and 3) scored the performance of the participants a second time at least 1 week after the initial scoring for the determination of preliminary intrarater reliability.
Data Analysis
To determine the concurrent validity of the scale, scores on each task of the RPS were correlated with those on the Chedoke-McMaster Stroke Assessment (arm and hand sections) using the coefficient eta deduced from an analysis of variance (ANOVA) and with those of the TEMPA and grip force measures using Pearson product moment correlation coefficients. The choice of the test relies on the type of variables correlated (continuous versus categorical). To measure discriminant validity, an ANOVA was done for subjects grouped into 3 levels according to the clinical severity of their condition (mild, moderate, severe). The level of severity was determined as the lower of the arm or hand scores on the Chedoke-McMaster Stroke Assessment. Multiple post hoc comparisons were then done to determine differences between groups (t test with Bonferroni correction: .05/number of comparisons). Preliminary intrarater and interrater reliability of the total score of the scale was estimated using ICCs that compare intrasubject variability with intersubject variability by ANOVA for a two-way random effect.34,35 For each ICC, a confidence interval of 95% was calculated.36 Reliability of data for each component of the scale was estimated with the weighted Cohen kappa. The Cohen kappa is a reliability coefficient designed for categorical variables that considers both the degree of agreement observed between 2 measurements and agreement due to the chance.37,38 The Cohen kappa also takes into account the degree of relative agreement (or disagreement) between 2 or more observations39 by attributing a weighting factor from 0 to 1 in each cell of the matrix. Agreement percentages also are provided.
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=70%, SD=13.5%) and kappa scores ranged from .14 to .85 (=.63, SD=.15), suggesting poor to excellent reliability (Tab. 7). Kappas were highest between raters 2 and 3 and were similar between raters 1 and 2 and between raters 1 and 3. The highest reliability values occurred for items 1, 4, 5, and 6, and the lowest reliability values occurred for items 2 and 3. The intrarater reliability on individual components of the scale also was analyzed using kappa statistics40 (Tab. 8). Reliability was moderate to excellent for rater 2 (kappa=.51–.85). In general, kappa values were good to excellent for rater 3 (kappa=.65–1.00), with the exception of the movement smoothness component of the scale (kappa=.18).
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| Discussion and Conclusions |
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Numerous previous studies have demonstrated relationships between impairments and activity limitations. For example, the impairment of the ability to perceive sustained pressure on the fingers has been correlated with deficits in fine motor tasks of the hand in patients with chronic hemiparesis.43 In addition, in patients with chronic hemiparesis, the presence of spasticity in the elbow flexors and extensors has been related to deficits in the ability to stabilize the forearm when a load is unexpectedly removed from the hand44 and the appearance of excessive agonist and antagonist elbow muscle coactivation when active elbow movement is attempted.45 A similar relationship has been demonstrated between impairment (Fugl-Meyer Assessment of Motor Recovery After Stroke) and activity scales such as the Motor Assessment Scale in its original version46 and its modified version.47
The interrater and intrarater reliability data reported here for the RPS are preliminary and are meant only as guidelines for further refinement of the scale content and for decisions about item inclusion or exclusion. The preliminary reliability data will be used to refine the scale, and a revised version of the scale will then be subjected to more rigorous reliability testing including a larger and more representative sample of individuals with hemiparesis and a larger number of raters. For example, item 6 (global score) of the RPS was included to measure the overall performance of the task when all components are considered together. This item evaluates the behavior at a "task" level and may be helpful in the task-oriented approach. Our preliminary analysis also suggests that separate ratings of compensations may be necessary for reaches to objects placed close to and far from the body. Of the 28 participants, half had identical scores for reaches to the near and far targets. Of these participants, 6 had little or no arm and hand deficit and 2 had severe movement limitations and were unable to perform the task at all. These results may suggest that, like many other impairment scales, a ceiling or floor effect may occur (ie, the scale may only be useful in identifying reaching and grasping compensations in patients with movement deficits between these 2 extremes). Determination of these effects will require testing a larger sample of patients.
In measurement, 3 main sources of variability may influence the results: the rater(s), the instrument, and the person being evaluated (participant). In general, ICCs revealed good or excellent preliminary reliability of the total RPS score (Tab. 5) according to the criteria proposed for ICCs by Sneeuw et al48 based on the interpretation scale of Landis and Kock.40 According to Sneeuw et al,48 an ICC of .81 to 1.00 is excellent, an ICC of .61 to .80 is good, an ICC of .41 to .60 is moderate, and an ICC of .40 or less is poor. Based on this interpretation, some of our lower confidence interval limits that were inferior to .61 may be considered as reflecting moderate reliability.
As we expected because the variability associated with the evaluators was low, preliminary intrarater reliability coefficients generally were higher than the interrater reliability coefficients. The preliminary reliability coefficients for the total RPS score were very good, indicating high agreement between raters and good stability over time. However, a systematic error (or bias) was found between raters, suggesting that the amount of clinical experience may have an impact on scoring. The amount of clinical experience of the raters will be taken into account in further reliability testing of the scale. Despite high mean values, confidence intervals for interrater reliability were wide. This finding suggests that in another study coefficients may be clearly lower or higher that those obtained in our study. These wide confidence intervals may be explained by our small sample size. Further reliability testing will be done on a larger, more representative sample of individuals with hemiparesis. In addition, the internal consistency of the tool will be evaluated.
As for the reliability of individual test items, kappa values for components 2 and 3 of the scale were poor, indicating that these scale items could be improved. In addition, some kappa values were clearly lower than the percentage of agreement associated with them. For example, for an agreement of 57% in the second component of task 1, a kappa value of .22 was calculated. Feinstein and Cicchetti49 reported that the distribution of scores in the matrix elaborated for the calculation of the kappa statistic may play an important role in the interpretation of the kappa values. They identified 2 paradoxes related to good percentages of agreement and low kappa values. The first paradox is that a good percentage of agreement may be reduced by a large difference in the sum of the rows or columns of the matrix. The second paradox is that higher kappa values will result from an asymmetrical difference than from a symmetrical one. The small size of our sample may be responsible for this imbalance because some cells of the matrix had no data leading to differences in the sums of rows and columns.
Aside from the small sample size, other factors may have influenced rater judgments to produce the low to moderate kappa values. It is likely that therapists who were not experienced in movement analysis may have had difficulty in reliably interpreting the written descriptions of movement. To diminish variability due to the instrument, more training could be provided on how to score the movements, or the wording of the scoring scale could be made more precise in order to improve agreement between raters with different levels of experience. The use of videotapes in our study, however, eliminated the variability related to the participants. Use of a videotape is recognized as a limitation of this study because variations in patient behavior from one evaluation to another is a realistic source of error present in practice. A further step in the reliability testing of the RPS, therefore, should be to evaluate the interrater reliability while therapists simultaneously observe the individual performing the reaching tasks.
One of the problems encountered when therapists attempt to assess the efficacy of intervention programs is the lack of tools sensitive to the movement parameters they specifically want to improve. Thus, there is often little choice but to use nonempirical or qualitative assessment to describe improvement, making it difficult to transfer information reliably between therapists. Although more complete reliability analysis is required, the RPS is a first step in the process of filling the clinical need to identify and quantify motor compensations used for reaching in individuals with hemiparesis of the arm. To our knowledge, it is the only scale of its kind for reaching movement. The RPS was able to discriminate among patients with different levels of motor impairment. The next step will be to improve the reliability of RPS scores by providing better written descriptions of scale items as well as written guidelines for therapists using the scale. Later studies should also examine the responsiveness of the scale to change. This testing is necessary to determine if the scale has the potential to become a useful tool in the assessment of the efficacy of interventions specifically aimed at diminishing compensatory movements of the shoulder girdle and trunk during reaching and manipulation tasks.
Limitations of the Study
Study limitations include the following considerations. First, this study was carried out with patients who were, as a group, younger than usual for people with strokes. In addition, the subjects were not randomly selected and those with severe cognitive, perceptual, or communication problems were excluded, leading to a nonrepresentative sample of people who had sustained a stroke. The small sample size of patients and raters for the preliminary reliability study limits the external validity of the results and the conclusions that could be drawn. The reliability study, therefore, should be considered as a preliminary one, giving essential data for a larger study.
Clinical Importance
In recent years, rehabilitation science has been placing increasing emphasis on the need for evidence-based practice.50,51 For motor rehabilitation, this naturally implies the development of better measurement scales to quantify motor recovery. The RPS is a direct result of the transfer of information from basic science to the clinical milieu.
Components of reaching in people without motor impairments and those with stroke were identified in a series of studies using highly sophisticated optical imaging techniques.1–4,24 Based on detailed movement analysis, elements of the motor pattern for reaching were identified as being lost or altered in groups of individuals with hemiparesis of the arm due to stroke, and these elements were incorporated into the RPS. This type of analysis resulted in more precise definitions of the motor elements lost in individuals with hemiparesis for reaching movements. How impairments in motor elements such as elbow extension, shoulder flexion, and movement smoothness relate to activity limitations reaching have not been identified despite their implicit inclusion in intervention approaches such as "shaping," "supervised task practice," and "task-oriented" therapy.5,13 Indeed, studies have shown that although there may be a trade-off between movement quality and movement speed (ie, insisting that the patient use more elbow extension for reaching, in some cases, may actually prolong the time to accomplish the task2) in the short term, improving control of isolated movements of the arm may diminish the development of abnormal movement synergies and the possibility of contracture formation in the long term.
Due to the lack of a clinical scale to assess these elements, improvements in motor performance have been difficult to identify. This study is a first step in the development of a motor compensation scale to assess the effectiveness of interventions aimed at increasing upper-extremity motor performance of individuals with hemiparesis of the arm due to stroke.
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The study was approved by the ethics committees of the Rehabilitation Institute of Montreal and the Sherbrooke Geriatric University Institute.
The study was supported by Quebec Provincial Network of Rehabilitation Research and the Quebec Health Research Fund.
* Sammons Preston/Rolyan, 4 Sammons Ct, Bolingbrook, IL 60440. 
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  M. D. Ellis, T. Sukal, T. DeMott, and J. P. A. Dewald Augmenting Clinical Evaluation of Hemiparetic Arm Movement With a Laboratory-Based Quantitative Measurement of Kinematics as a Function of Limb Loading Neurorehabil Neural Repair, July 1, 2008; 22(4): 321 - 329. [Abstract] [PDF]
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