CRITICALLY APPRAISED PAPER (CAP) Couillet, J., Soury, S., Lebornec, G., Asloun, S., Joseph, P., Mazaux, J., & Azouvi, P. (2010). Rehabilitation of divided attention after severe traumatic brain injury: A randomised trial. Neuropsychological Rehabilitation, 20, 321 339. http://dx.doi.org/10.1080/09602010903467746 CLINICAL BOTTOM LINE: This study demonstrates that dual-task training has a positive effect on divided attention outcomes for clients with subacute and chronic severe traumatic brain injury (TBI). Because attention deficits are one of the most common and debilitating outcomes involved in TBI, these findings are important for clinicians working with this population to consider. Clinicians, occupational therapists in particular, who focus their therapy around functional tasks need to realize the importance of not only attention to a single task but divided attention on multiple tasks, which is more applicable to everyday life experiences. Occupational therapists working with clients with severe TBI in a subacute or chronic phase can use this knowledge to implement functional tasks in their sessions that require divided attention between multiple aspects within a task, rather than just one task, to better prepare their clients for independent living. This study contains few measurement biases, so it is of acceptable validity. It is a welldesigned study using a Level III, one-group, AB versus BA crossover design with an experimental and control task-training technique; however, future research in this area could be improved by the creation of a Level I randomized controlled trial study and by the use of a more reliable measure for divided attention in everyday life. Findings in this study indicate that dualtask training has potential for benefit in areas of divided attention if implemented in occupational therapy sessions; however, practitioners should perform dual-task training in more naturalistic settings than this study provides. RESEARCH OBJECTIVE(S) List study objectives. Determine effects of a specific dual-task training rehabilitation program on divided attention for individuals with severe TBI at subacute and chronic stages Compare the effects of dual-task training rehabilitation with the effects of traditional single-task training DESIGN TYPE AND LEVEL OF EVIDENCE: 1
Level III: One-group AB versus BA crossover design SAMPLE SELECTION How were subjects recruited and selected to participate? Please describe. The sample was drawn from patients referred to one of two specialized neurorehabilitation units in the subacute or chronic stage of severe TBI (5 or more months after TBI was sustained). Severe TBI was defined here as a score of 8 or less on the Glasgow Coma Scale. The 12 patients were randomized to two groups, one of which received the control (single-task training) first, and the other of which received the intervention (dual-task training) first. Inclusion Criteria Participants had to be out of posttraumatic amnesia, as defined by a score of 76 or more on two consecutive days on the Galveston Orientation and Amnesia Test (p. 324). Participants had to have a deficit in divided attention, which was demonstrated by a score below the fifth percentile on the Divided Attention subtest of the Test for Attentional Performance and also by a complaint of difficulty performing two tasks at once on the Rating Scale of Attentional Behavior. Exclusion Criteria Previous psychiatric or neurological diseases, substance abuse, severe behavioral modifications, motor or visual impairments or severe cognitive deficits that precluded completion of the rehabilitation program were all exclusion criteria for this study (p. 324). SAMPLE CHARACTERISTICS N= (Number of participants taking part in the study) 12 (3 did not participate in follow-up measures) #/ (%) Male 9 (75%) #/ (%) Female 3 (25%) Ethnicity NR Disease/disability diagnosis Subacute or chronic severe TBI with divided attention deficits INTERVENTION(S) AND CONTROL GROUPS Add groups if necessary Group 1: AB (control training, then experimental rehabilitation) Brief description of the intervention Phase A control training: One hour of performance of single cognitive tasks, either computerized or with paper and pencil, that did not require the use of working memory or divided attention to complete. Examples included simple visual search tasks, verbal and 2
How many participants in the group? Where did the intervention take place? Who Delivered? How often? For how long? visual long-term memory tasks, problem solving, crosswords, and summarizing short texts. Phase B experimental rehabilitation: One hour of performance of dual tasks, either computerized or with paper and pencil. The two tasks were first introduced separately, then given at the same time. When clients reached a 90% on tasks, the tasks increased in difficulty in use of working memory and divided attention. The tasks, as well as the combination of tasks, changed each session. Examples included choice reaction time, forward and backward counting, word spelling, and summarizing short texts. Researchers also implemented activities of daily living and instrumental activities of daily living when appropriate, such as cooking, managing money, and shopping. n = 5 One of two specialized neurorehabilitation units (specific locations NR) Therapists (specific professions not reported) Administered as four individual 1-hr sessions per week 24 hr of training per phase (48 hr total) 6 weeks for Phase A, and 6 weeks for Phase B (12 weeks total) Group 2: BA (experimental rehabilitation, then control training) Brief description of the intervention How many participants in the group? Where did the Phase A experimental rehabilitation: One hour of performance of dual tasks, either computerized or with paper and pencil. The two tasks were first introduced separately, then given at the same time. When clients reached a 90% on tasks, the tasks increased in difficulty in use of working memory and divided attention. The tasks, as well as the combination of tasks, changed each session. Examples included choice reaction time, forward and backward counting, word spelling, and summarizing short texts. Researchers also implemented activities of daily living and instrumental activities of daily living when appropriate, such as cooking, managing money, and shopping. Phase B control training: One hour of performance of single cognitive tasks, either computerized or with paper and pencil, that did not require the use of working memory or divided attention to complete. Examples included simple visual search tasks, verbal and visual long-term memory tasks, problem solving, crosswords, and summarizing short texts. n = 7 One of two specialized neurorehabilitation units (specific locations 3
intervention take place? Who Delivered? How often? For how long? NR) Therapists (specific professions not reported) Administered as four individual 1-hr sessions per week 24 hr of training per phase (48 hr total) 6 weeks for Phase A, and 6 weeks for Phase B (12 weeks total) Intervention Biases: Check yes, no, or NR and explain, if needed. Contamination: There is possible contamination bias in this study, because all participants received both dual-task training and single-task training intervention strategies. Co-intervention: Because participants in the study were also clients at the two neurorehabilitation facilities used, it can be assumed that they were receiving occupational, physical, or speech therapy or a combination of these. Timing: Site: YES NO Because the study was carried out over a period of 12 weeks, it is difficult to know whether the AB group, receiving the intervention in the second 6-week phase, had an advantage over the BA group. All participants were 5 months or more postinjury, so spontaneous recovery was not a problem in this study. Comment No bias toward one group or the other, because both groups performed in the same setting. Use of different therapists to provide intervention: YES NR MEASURES AND OUTCOMES Complete for each measure relevant to occupational therapy: Measure 1: Divided Attention subtest of the Test of Attentional Performance (TAP), 4
Measure 2: Measure 3: Measure 4: reaction time a specific divided attention measure Reaction times during a dual task, to assess divided attention Divided Attention subtest of the TAP, omissions specific divided attention measure Number of omissions during a dual task, to assess divided attention Go no go dual task, reaction times a specific divided attention measure Reaction times during task, to assess divided attention Go no go dual task, omissions specific divided attention measure Number of omissions during task, to assess divided attention 5
Measure 5: Measure 6: Measure 7: Measure 8: Digit span dual task, percentage of hits specific divided attention measure Percentage of hits during task, to assess divided attention Flexibility subtest of the TAP Mean reaction times, to assess executive functioning and working memory, or mental flexibility Trail-Making Test (B A) Difference between time of completion of Form B and Form A, to assess executive functioning and working memory, or mental flexibility Stroop Test Interference score (difference between interference and reading condition), to assess inhibition and attention 6
Measure 9: Measure 10: Working memory: Brown Peterson Paradigm Percentage of hits under the mental calculation as interfering task, to assess simultaneous storage and processing of information Rating Scale of Attentional Behavior Divided Attention question Mean score of the Divided Attention question of the scale (range 0 4), to assess client s observations of abilities in divided attention in everyday life YES NO Measurement Biases Were the evaluators blind to treatment status? Check yes, no, or NR, and if no, explain. YES NO The researchers stated that assessment was not able to be blinded for practical reasons (p. 337). Recall or memory bias. Check yes, no, or NR, and if yes, explain. YES NR RESULTS List key findings based on study objectives Include statistical significance where appropriate (p<0.05) Include effect size if reported 7
For all outcome measures, the main effect of group was non-significant on repeatedmeasures ANOVAs (all ps >.1), suggesting that the two groups did not differ in terms of baseline cognitive impairments (p. 329). For the Divided Attention subscale of the TAP, experimental dual-task training demonstrated a large effect (Cohen s d > 1.5) on reaction times and omissions, and control single-task training only demonstrated a small effect (d < 0.2). For the go no go task and digit span dual task, experimental dual-task training demonstrated a large effect (d > 0.8) for reaction times, omissions, and percentage of hits, whereas the control single-task training only demonstrated a small effect once again. For the executive and working memory tasks, post-hoc comparison revealed no significant between-group difference (p. 331) for measures on the Flexibility subtest of the TAP as well as the Stroop Test. The effect of time was not statistically significant for the Trail-Making Test or the Brown Peterson Task, either. Effect sizes for the experimental dual-task training on executive and working memory were moderate to large (d > 0.5), and, once again, the effect sizes were small for the control single-task training. For the measure of divided attention in everyday life, the between-groups difference was found to be statistically significant (p <.01) because the BA group scored lower. The effect size of experimental training was large here but was very minimal for control training. For simple reaction time, the two groups demonstrated no significant differences at the end of the first 6-week phase (p >.1). The go no go and digit span tasks performed alone displayed statistical significance, with an effect of time (p <.01). Experimental dual-task training had less of an effect on these measures (d range = 0.2 0.8) than it did on previous measures. Was this study adequately powered (large enough to show a difference)? Check yes, no, or NR, and if no, explain. Were appropriate analytic methods used? Check yes, no, or NR, and if no, explain. Were statistics appropriately reported (in written or table format)? Check yes or no, and if no, explain. Was the percent/number of subjects/participants who dropped out of the study reported? 8
Limitations: What are the overall study limitations? Limitations of this study include a small sample size, lack of blinding for the clinician evaluators, lack of generalization to everyday activities, and a dropout rate of 25% before retrieval of follow-up data. The researchers reported that blinding in this study was not practical. They also stated that future studies should use more everyday life divided attention measures to make the study more applicable to a client s typical setting rather than a rehabilitation setting. CONCLUSIONS State the authors conclusions related to the research objectives. In conclusion, the authors stated that the group that received the experimental dual-task treatment condition first (BA) performed significantly better than the group that received it second (AB) when assessed after the first 6-week phase in dual-task outcome measures specific to divided attention. This indicates that dual-task training is more effective than single-task training when one is looking to improve divided attention in clients with severe TBI. Less of an effect was shown for this experimental treatment condition in regard to improvement in executive function and working memory, which indicates that dual-task training may not be appropriate if the rehabilitation focus is on either of these two factors rather than specifically on divided attention. The authors noted that this dual-task training did not have an effect on how the tasks were performed when split up to be performed as single tasks, which indicates again that this type of training should only be used when one is looking to specifically improve divided attention. More research is recommended to help clinicians treat and assess divided attention in a more naturalistic setting, rather than strictly a rehabilitation setting. This work is based on the evidence-based literature review completed by Morgan Schulte, OTS, and Kelly Erickson, PhD, OTR/L, Faculty Advisor, College of St. Scholastica. CAP Worksheet adapted from Critical Review Form Quantitative Studies. Copyright 1998, by M. Law, D. Stewart, N. Pollack, L. Letts, J. Bosch, & M. Westmorland, McMaster University. Used with permission. For personal or educational use only. All other uses require permission from AOTA. Contact: www.copyright.com 9