Method for Enhancing Real-World Use of a More Affected Arm in Chronic Stroke
Transfer Package of Constraint-Induced Movement Therapy
Background and Purpose—Constraint-induced movement therapy is a set of treatments for rehabilitating motor function after central nervous system damage. We assessed the roles of its 2 main components.
Methods—A 2×2 factorial components analysis with random assignment was conducted. The 2 factors were type of training and presence/absence of a set of techniques to facilitate transfer of therapeutic gains from the laboratory to the life situation (Transfer Package; TP). Participants (N=40) were outpatients ≥1-year after stroke with hemiparesis. The different treatments, which in each case targeted the more affected arm, lasted 3.5 hours/d for 10 weekdays. Spontaneous use of the more affected arm in daily life and maximum motor capacity of that arm in the laboratory were assessed with the Motor Activity Log and the Wolf Motor Function Test, respectively.
Results—Use of the TP, regardless of the type of training received, resulted in Motor Activity Log gains that were 2.4 times as large as the gains in its absence (P<0.01). These clinical results parallel previously reported effects of the TP on neuroplastic change. Both the TP and training by shaping enhanced gains on the Wolf Motor Function Test (P<0.05). The Motor Activity Log gains were retained without loss 1 year after treatment. An additional substudy (N=10) showed that a single component of the TP, weekly telephone contact with participants for 1 month after treatment, doubled Motor Activity Log scores at 6-month follow-up.
Conclusions—The TP is a method for enhancing both spontaneous use of a more affected arm after chronic stroke and its maximum motor capacity. Shaping enhances the latter.
- constraint-induced movement therapy
- stroke rehabilitation
- task practice
- transfer package
Constraint-induced movement therapy (CI therapy) has been found in multiple randomized controlled trials to be efficacious for rehabilitating upper-extremity function in chronic and subacute stroke in adults1 and cerebral palsy in children from 1 year through adolescence.2 Case series support the efficacy of CI therapy for rehabilitating upper-extremity function in traumatic brain injury3 and multiple sclerosis,4 and lower-extremity function in chronic stroke,5 traumatic brain injury,6 and multiple sclerosis.7 The magnitude of the treatment effect that has been reported, however, has been markedly variable.
The upper-extremity CI therapy protocol, as practiced in this laboratory, consists of 4 basic components8–10: (1) intensive training of the more affected arm for multiple days; (2) training by shaping (see Interventions section); (3) the transfer package (TP), a set of behavioral techniques to facilitate transfer of therapeutic gains from the treatment setting to daily life (see Interventions section and Methods in the online-only Data Supplement); and (4) prolonged motor restriction of the less affected arm.
In a representative randomized controlled trial of the full CI therapy protocol from this laboratory with 41 patients with chronic stroke, the value of the effect size index d for post-treatment gains in real-world spontaneous use of the more affected arm was 3.6.8 For comparison, 0.8 is considered a large value in the meta-analysis literature.11 All but 2 of the >400 CI therapy studies published by other laboratories report a positive treatment effect, but it is usually smaller than that obtained here. For example, a widely cited meta-analysis reports a mean d value of 0.8 for 21 CI therapy studies (total N=508), ≈1/3 the d value reported here.12 However, most of these studies used attenuated or partial versions of our method. The usual missing component is the TP. In contrast, the results from this laboratory have been largely duplicated in studies from 4 laboratories that adhered to our method and whose therapists were trained here.13–16
Previous studies have found prolonged restraint of the less affected arm is not necessary to obtain a full treatment effect.5,17,18 This article reports on a study testing the contribution of 2 other components: training with shaping and the TP. In a previous article derived from this study using voxel-based morphometry, we reported that treatment with the full CI therapy protocol, including the TP, resulted in a profuse increase in gray matter in motor areas of the brain. Use of the same protocol, but with no TP, did not produce any detectable neuroplastic changes.19 The clinical findings from the subjects in that study are reported here; subjects were recruited from 2005–2007.
Study 1: Methods
Participants, Randomization, and Informed Consent
Forty-five community residents ≥1-year after stroke with upper-extremity hemiparesis were enrolled; 40 completed treatment (Figure 1). All had mild-to-moderate motor impairment of the more affected arm, which is categorized as a grade 2 deficit according to a classification schema used in CI therapy studies (Table I in the online-only Data Supplement).20 Specifically, participants were required to have extension of ≥10° at the metacarpophalangeal and one of the interphalangeal joints of each finger, ≥10° extension or abduction of the thumb, and ≥20° extension of the wrist from a fully flexed starting position.8,21 Exclusion criteria were as follows: (1) presence of medical conditions severe enough to interfere with participation in treatment; (2) profound bilateral hearing loss with use of hearing aids (90 dB or worse); (3) legally blind status; (4) ferrous metal in the body or any condition that would preclude an MRI; (5) uncontrolled seizures; (6) pharmacological treatment for motor disability ≤3 months before treatment, for example, botulinum toxin or oral/intrathecal baclofen; and (7) previous CI therapy.
All participants provided signed informed consent before randomization. The study was performed at the University of Alabama at Birmingham, where the institutional review board for human research approved the research. Participants were informed that they would be enrolling in a project to test the importance of different components of CI therapy. Participants were randomized in equal numbers using a computer-generated random numbers table to receive 1 of 4 possible combinations of the 2 factors to be tested: presence versus absence of the TP (+TP versus –TP) and training with shaping versus repetitive task practice (shaping versus repetition; Figure 1).
Components analysis was conducted with a 2×2 factorial design. The possible combinations of the 2 treatment factors were represented by 4 separate groups: shaping+TP, repetition+TP, shaping-No TP, repetition-No TP.
For all groups, training took place for 10 consecutive weekdays; 3 hours/d training +0.5 hours/d TP for the 2 +TP groups, and 3.5 hours/d training for the 2 −TP groups. The amount of in-laboratory treatment and participant–therapist interaction was thus equivalent between groups. In the +TP groups, participants wore a heavily padded safety mitt on their less affected arm to prevent use of that hand for a target of 90% of waking hours for the entire 14-day treatment period (10 training days plus 4 weekend days). In the −TP groups, participants wore the safety mitt for only in-laboratory treatment.
Shaping is a training method in which a motor or behavioral objective is approached in small steps by successive approximations (ie, a task is gradually made more difficult with respect to a participant’s motor capabilities). Its principles were explicitly formulated by Skinner,22,23 and they have been applied to the rehabilitation of movement.21,24 A more detailed description of the shaping process is presented in Methods in the online-only Data Supplement.
Repetitive Task Practice
The same or similar tasks were used with the same schedule of administration as in shaping, and the participants were encouraged to keep trying, but no feedback was given, and tasks of increasing difficulty were not introduced.
The TP consists of a set of techniques in common use in the behavioral analysis field for the treatment of a variety of conditions, but they have not been used systematically in rehabilitation. The techniques used here are as follows: behavioral contracts, daily home diary, daily administration of the Motor Activity Log (MAL) to track amount and quality of use of the more affected arm in 30 important Activities of Daily Living (ADL), problem solving to overcome perceived barriers to more affected arm use in ADL performance, written assignment of practice at home of both tasks performed in the laboratory, and use of the more affected arm in specified ADL, post-treatment home skill practice assignments, weekly telephone calls for the first month after laboratory treatment in which the MAL is given, and problem solving performance. The procedures are described in detail in Methods in the online-only Data Supplement.
The MAL is a scripted, structured interview21 that is reliable and valid.25 Evidence for validity of the MAL includes a strong correlation (r, range =0.71–0.91; P≤0.01) with accelerometry, an objective measure of amount of movement in the life situation.26 Participants are asked to rate the quality of movement and amount of use of their more affected arm in daily life on 30 upper-extremity activities over a specified period (eg, past week, yesterday). Only the quality of movement rating, named the Arm Use scale, is reported here because the 2 ratings are highly correlated (r=0.95; P=0.0001), and hence redundant.8,19,20,25 The minimum detectable change on the MAL Arm Use scale is 0.5 points (10% of full scale range).25,26 The test score is the mean of the item scores. The Wolf Motor Function Test (WMFT) is a valid and reliable measure of in-laboratory motor capacity (ie, maximum ability), when a participant is asked to complete a task with the more affected arm.27,28 Time to complete each of 15 upper-extremity actions or tasks is recorded. The test score is the mean of the item “Performance Time scores” after transforming them into a rate (repetitions per minute).29 The MRI results from the subjects in this study have been reported previously.19
Mixed model, repeated measures ANOVAs were used to test the independent and interdependent effects, if any, of the presence of the TP and type of training on pre- to post-treatment outcomes. Parallel models, which substituted test scores at 1-year follow-up for the post-treatment values, were used to evaluate the long-term effects of these components of CI therapy. Inspection of the group means and corresponding confidence intervals permitted description of the differences in outcomes between particular groups and testing occasions. The analysis was conducted on a per-protocol basis because the purpose of this components analysis was to identify the contribution of receiving particular components of CI therapy on treatment outcome. Two-tailed tests with an α of 0.05 were used. To control the study-wide inflation of type I error, simple contrasts (eg, comparing individual groups to one another) were only conducted if the relevant omnibus test was significant.30 The f statistic11 was used to index the effect size of the differences in treatment gains between the groups; values ≥0.4 are considered large. The d′ statistic was used to index the effect size of the changes within each group or combination of groups; values 0.57 are considered large.
Trial Profile and Initial Participant Characteristics
Of 289 candidates screened by telephone, 56 were enrolled. Of this number, 45 were randomized to 1 of the 4 groups in Study 1, and 11 were randomized to the single group in Study 2 (see Study 2: Methods and Results). In Study 1, 89% completed treatment and 80% completed MALs at 1-year follow-up. There was no difference in drop-out between groups at either post-treatment (P=0.793) or 1-year follow-up (P=0.741). Figure 1 shows the trial profile and numbers randomized to and completing treatment in each group, along with reasons for drop-out.
Study 1: Results
Participants were, on average, 63 years of age (range =29–88) and 3.9 years after stroke (range =1.0–11.0). Thirty-eight were right dominant before stroke; 16 had paresis on the right side. There were no significant differences at pretreatment between the Study 1 groups on any of the characteristics listed in Table II in the online-only Data Supplement (P, range=0.16–0.36), including expectation of benefit from treatment (P=0.20). Nor were there pretreatment differences on the MAL (P=0.92; Table III in the online-only Data Supplement) or WMFT (P=0.74; Table IV in the online-only Data Supplement).
Changes From Pre- to Post-treatment
Table III in the online-only Data Supplement and Figure 2A show changes at post-treatment on the MAL. Use of the TP, regardless of type of training received, resulted in gains in spontaneous use of the more affected arm in the life situation that were significantly larger than those observed in its absence (mean difference in MAL gains =1.2 points; P<0.01). Type of training received did not affect MAL gains (mean difference =0.2; P=0.495). Inspection of the mean changes in each group reveals that although the −TP groups had MAL gains that were greater than the minimum detectable change on this test (Shaping−TP, mean=0.7; Repetition−TP, mean=0.8), the +TP groups had changes that were more than twice as large (Shaping+TP, mean=1.8; Repetition+TP, mean=2.1).
Table IV in the online-only Data Supplement and Figure 2C show post-treatment changes on the WMFT, which, as noted, measures maximum motor capacity in the laboratory. Use of the TP and training with shaping each made independent contributions to post-treatment WMFT Performance Rate gains (+TP versus −TP; mean difference =6.4 repetitions/min, P<0.05; Shaping versus Repetition, mean difference =5.4, P<0.05). Inspection of the mean changes within each group suggests that effects of these 2 factors were additive. Absence of both the TP and shaping resulted in no gains: Repetition−TP group, mean = −0.3. Presence of the TP or of shaping resulted in similar gains: Repetition+TP group, mean=5.7; Shaping−TP group, mean=4.7. Presence of both factors resulted in gains that were nearly double those when 1 factor alone was present: Shaping+TP group, mean=11.6.
The magnitude of the enhancement in treatment outcome produced by the TP in spontaneous use of the more affected arm in the real world (MAL) was twice as large as that for maximum motor capacity of that arm (WMFT; f=0.8 vs 0.4; Tables III and IV in the online-only Data Supplement), which is consistent with previous data from this laboratory.5,8,9,21 Notwithstanding the difference between these 2 aspects of motor function in magnitude of treatment gains, there was a moderate correlation between them both before treatment (r=0.44; P<0.01) and with respect to treatment change (r=0.55, P<0.001) across all participants.
Changes From Pretreatment to 1 Year After Treatment
As may be seen from Table III in the online-only Data Supplement and Figure 2B, there was no decrement in MAL scores after treatment ended in any of the 4 groups. Thus, the pattern of findings with respect to real-world outcome was the same at 1-year follow-up as at post-treatment.
Study 2: Methods and Results
A separate study was performed to assess the effect of a single component of the TP, weekly phone contact with participants for the first month after treatment, and on post-treatment retention. The participants were randomly selected from the same pool of potential participants as used in Study 1 (Figure 1). None of their characteristics were significantly different from those of the participants in Study 1 (Table II and Table V in the online-only Data Supplement). During treatment, they were given repetitive task practice and no TP, just as the Repetition−TP group in Study 1. Figure 3 shows that pre- to post-treatment change on the MAL was virtually the same for these 2 groups. However, the addition of 4 weekly phone contacts for the first month after treatment substantially increased the spontaneous use of the more affected arm in the life situation. Six months after treatment, the MAL gains in this group bridged approximately one half the gap in MAL gains at post-treatment between the repetitive task practice groups with and without the TP. At 1-year follow-up, the MAL score in this group had decreased to the level of the Repetition−TP group at that occasion, suggesting that other elements of the TP are needed to sustain MAL gains over the longer-time interval at the higher level.
The current consensus in physical rehabilitation, including the perspective of patients, researchers, clinicians, and health care payers, is that functional activity in the life situation is the most important outcome to pursue.31–33 In the present experiment, training in the laboratory/clinic by itself produced a substantial real-world effect. However, the TP was by far more important for inducing transfer of training from the treatment setting to the activities of daily living, increasing real-world treatment effect by a factor of almost 2.5.
The 2 TP groups scored a mean of 1.2 on the MAL Arm Use scale at the beginning of treatment and ended treatment 2 weeks later scoring 3.1. A rating of 3, according to the verbal anchor presented to participants, represents an ability to perform a daily life activity independently. A post-treatment test score of 3.1 indicates that after treatment, participants were performing approximately half the 30 ADLs tracked by the MAL without the aid of the less affected arm or an external source. Converting the mean scores to the percentile scale presented to participants, the spontaneous use of the more affected arm compared to before stroke improved from 12% before treatment to 53% after treatment, an increase of 4.4 times due to treatment. This is consistent with previous research from this laboratory.8,34
Improvement on the MAL at post-treatment was 2.4 times greater in the groups that received the TP than in the groups that did not, even though all groups received more affected arm training of the same duration and intensity. Moreover, this advantage persisted for the entire year of follow-up; there was no decrement in MAL gains in any of the Study 1 groups. The power of TP is further indicated by the fact that the introduction of a single one of its components in Study 2, weekly phone contacts for the first month after treatment, resulted in bridging the performance gap between groups with and without the TP at post-treatment by half, 6 months afterward. In future research, it would be of value to perform components analysis to determine the role of each of the individual elements of the TP.
The question arises as to whether the TP increases treatment effect by increasing the amount of practice of more affected arm use. Alternatively, it is possible that the TP promotes integration of therapeutic gains achieved in the laboratory into real-world activities so that more affected arm use becomes habitual. These 2 possibilities are not mutually exclusive. Addressing this question in future research would be of mechanistic and theoretical interest; however, from the point of view of practical therapeutics, the resolution of this important issue does not really matter. The TP seems to be a means of increasing real-world treatment outcome that does not involve increasing costly therapist time; this would be of considerable value whatever the mechanism by which the TP achieved its effect.
Sources of Funding
This research was supported by grant HD34273 from the National Institutes of Health.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.111.000559/-/DC1.
- © 2013 American Heart Association, Inc.
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