Dose Articulation in Preclinical and Clinical Stroke Recovery: Refining a Discovery Research Pipeline and Presenting a Scoping Review Protocol

Considerations for developing complex post-stroke upper limb behavioural interventions: An international qualitative study

OBJECTIVE

To simultaneously explore the perspectives and opinions of different invested participant groups on the important considerations for development of upper limb behavioural interventions that drive optimal post-stroke upper limb motor recovery.

DESIGN

A qualitative descriptive study in a constructivist epistemology.

PARTICIPANTS

Purposively selected participant groups (preclinical research n = 9, clinical research n = 9, clinical experience n = 9 and lived experience n = 10).

SETTING

Research participants were selected from top internationally published authors. Experiential participants were recruited internationally, through networks.

RESULTS

Four themes were identified with embedded subthemes. Theme 1: 'Clinical relevance should be the core of a "good" research question' with two subthemes: 'Breaking down silos: forging interdisciplinary research teams', and 'Beyond the pipeline: bench to bedside and back'; theme 2: 'Balance restitution and compensation to maximise outcomes' with three subthemes: 'Good outcome: going beyond an outcome measure', 'Recovery is a puzzle: measure all the pieces', and 'Optimising capacity: knowing when and how'; theme 3: 'Stroke demands personalised solutions' with two subthemes: 'Condition-specific considerations', and 'Person-specific considerations'; theme 4: 'Upper limb recovery requires complex interventions' with four subthemes: 'Fuelling engagement', 'Content is crucial', 'Multidimensional dose', and 'Therapist sway'.

CONCLUSIONS

This study suggests that post-stroke upper limb motor interventions are the interactions of multiple intervention elements (e.g. dose and content) shaped by different contextual considerations (e.g. stroke and personal factors). Development of such interventions may need to consider both content and context of the intervention to drive optimal recovery.

Analysis of animal-to-human translation shows that only 5% of animal-tested therapeutic interventions obtain regulatory approval for human applications

There is an ongoing debate about the value of animal experiments to inform medical practice, yet there are limited data on how well therapies developed in animal studies translate to humans. We aimed to assess 2 measures of translation across various biomedical fields: (1) The proportion of therapies which transition from animal studies to human application, including involved timeframes; and (2) the consistency between animal and human study results. Thus, we conducted an umbrella review, including English systematic reviews that evaluated the translation of therapies from animals to humans. Medline, Embase, and Web of Science Core Collection were searched from inception until August 1, 2023. We assessed the proportion of therapeutic interventions advancing to any human study, a randomized controlled trial (RCT), and regulatory approval. We meta-analyzed the concordance between animal and human studies. The risk of bias was probed using a 10-item checklist for systematic reviews. We included 122 articles, describing 54 distinct human diseases and 367 therapeutic interventions. Neurological diseases were the focus of 32% of reviews. The overall proportion of therapies progressing from animal studies was 50% to human studies, 40% to RCTs, and 5% to regulatory approval. Notably, our meta-analysis showed an 86% concordance between positive results in animal and clinical studies. The median transition times from animal studies were 5, 7, and 10 years to reach any human study, an RCT, and regulatory approval, respectively. We conclude that, contrary to widespread assertions, the rate of successful animal-to-human translation may be higher than previously reported. Nonetheless, the low rate of final approval indicates potential deficiencies in the design of both animal studies and early clinical trials. To ameliorate the efficacy of translating therapies from bench to bedside, we advocate for enhanced study design robustness and the reinforcement of generalizability.

Control intervention design for preclinical and clinical trials: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable

Control comparator selection is a critical trial design issue. Preclinical and clinical investigators who are doing trials of stroke recovery and rehabilitation interventions must carefully consider the appropriateness and relevance of their chosen control comparator as the benefit of an experimental intervention is established relative to a comparator. Establishing a strong rationale for a selected comparator improves the integrity of the trial and validity of its findings. This Stroke Recovery and Rehabilitation Roundtable (SRRR) taskforce used a graph theory voting system to rank the importance and ease of addressing challenges during control comparator design. "Identifying appropriate type of control" was ranked easy to address and very important, "variability in usual care" was ranked hard to address and of low importance, and "understanding the content of the control and how it differs from the experimental intervention" was ranked very important but not easy to address. The CONtrol DeSIGN (CONSIGN) decision support tool was developed to address the identified challenges and enhance comparator selection, description, and reporting. CONSIGN is a web-based tool inclusive of seven steps that guide the user through control comparator design. The tool was refined through multiple rounds of pilot testing that included more than 130 people working in neurorehabilitation research. Four hypothetical exemplar trials, which span preclinical, mood, aphasia, and motor recovery, demonstrate how the tool can be applied in practice. Six consensus recommendations are defined that span research domains, professional disciplines, and international borders.

Control intervention design for preclinical and clinical trials: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable

Control comparator selection is a critical trial design issue. Preclinical and clinical investigators who are doing trials of stroke recovery and rehabilitation interventions must carefully consider the appropriateness and relevance of their chosen control comparator as the benefit of an experimental intervention is established relative to a comparator. Establishing a strong rationale for a selected comparator improves the integrity of the trial and validity of its findings. This Stroke Recovery and Rehabilitation Roundtable (SRRR) taskforce used a graph theory voting system to rank the importance and ease of addressing challenges during control comparator design. "Identifying appropriate type of control" was ranked easy to address and very important, "variability in usual care" was ranked hard to address and of low importance, and "understanding the content of the control and how it differs from the experimental intervention" was ranked very important but not easy to address. The CONtrol DeSIGN (CONSIGN) decision support tool was developed to address the identified challenges and enhance comparator selection, description, and reporting. CONSIGN is a web-based tool inclusive of seven steps that guide the user through control comparator design. The tool was refined through multiple rounds of pilot testing that included more than 130 people working in neurorehabilitation research. Four hypothetical exemplar trials, which span preclinical, mood, aphasia, and motor recovery, demonstrate how the tool can be applied in practice. Six consensus recommendations are defined that span research domains, professional disciplines, and international borders.

Examining Dose Frameworks to Improve Aphasia Rehabilitation Research

The effect of treatment dose on recovery of post-stroke aphasia is not well understood. Inconsistent conceptualization, measurement, and reporting of the multiple dimensions of dose hinders efforts to evaluate dose-response relations in aphasia rehabilitation research. We review the state of dose conceptualization in aphasia rehabilitation and compare the applicability of 3 existing dose frameworks to aphasia rehabilitation research-the Frequency, Intensity, Time, and Type (FITT) principle, the Cumulative Intervention Intensity (CII) framework, and the Multidimensional Dose Articulation Framework (MDAF). The MDAF specifies dose in greater detail than the CII framework and the FITT principle. On this basis, we selected the MDAF to be applied to 3 diverse examples of aphasia rehabilitation research. We next critically examined applicability of the MDAF to aphasia rehabilitation research and identified the next steps needed to systematically conceptualize, measure, and report the multiple dimensions of dose, which together can progress understanding of the effect of treatment dose on outcomes for people with aphasia after stroke. Further consideration is required to enable application of this framework to aphasia interventions that focus on participation, personal, and environmental interventions and to understand how the construct of episode difficulty applies across therapeutic activities used in aphasia interventions.

Using Robot-Based Variables during Upper Limb Robot-Assisted Training in Subacute Stroke Patients to Quantify Treatment Dose

In post-stroke motor rehabilitation, treatment dose description is estimated approximately. The aim of this retrospective study was to quantify the treatment dose using robot-measured variables during robot-assisted training in patients with subacute stroke. Thirty-six patients performed fifteen 60 min sessions (Session 1−Session 15) of planar, target-directed movements in addition to occupational therapy over 4 (SD 2) weeks. Fugl−Meyer Assessment (FMA) was carried out pre- and post-treatment. The actual time practiced (percentage of a 60 min session), the number of repeated movements, and the total distance traveled were analyzed across sessions for each training modality: assist as needed, unassisted, and against resistance. The FMA score improved post-treatment by 11 (10) points (Session 1 vs. Session 15, p < 0.001). In Session 6, all modalities pooled, the number of repeated movements increased by 129 (252) (vs. Session 1, p = 0.043), the total distance traveled increased by 1743 (3345) cm (vs. Session 1, p = 0.045), and the actual time practiced remained unchanged. In Session 15, the actual time practiced showed changes only in the assist-as-needed modality: −13 (23) % (vs. Session 1, p = 0.013). This description of changes in quantitative-practice-related variables when using different robotic training modalities provides comprehensive information related to the treatment dose in rehabilitation. The treatment dose intensity may be enhanced by increasing both the number of movements and the motor difficulty of performing each movement.

Timing and Dose of Upper Limb Motor Intervention After Stroke: A Systematic Review

This systematic review aimed to investigate timing, dose, and efficacy of upper limb intervention during the first 6 months poststroke. Three online databases were searched up to July 2020. Titles/abstracts/full-text were reviewed independently by 2 authors. Randomized and nonrandomized studies that enrolled people within the first 6 months poststroke, aimed to improve upper limb recovery, and completed preintervention and postintervention assessments were included. Risk of bias was assessed using Cochrane reporting tools. Studies were examined by timing (recovery epoch), dose, and intervention type. Two hundred and sixty-one studies were included, representing 228 (n=9704 participants) unique data sets. The number of studies completed increased from one (n=37 participants) between 1980 and 1984 to 91 (n=4417 participants) between 2015 and 2019. Timing of intervention start has not changed (median 38 days, interquartile range [IQR], 22-66) and study sample size remains small (median n=30, IQR 20-48). Most studies were rated high risk of bias (62%). Study participants were enrolled at different recovery epochs: 1 hyperacute (<24 hours), 13 acute (1-7 days), 176 early subacute (8-90 days), 34 late subacute (91-180 days), and 4 were unable to be classified to an epoch. For both the intervention and control groups, the median dose was 45 (IQR, 600-1430) min/session, 1 (IQR, 1-1) session/d, 5 (IQR, 5-5) d/wk for 4 (IQR, 3-5) weeks. The most common interventions tested were electromechanical (n=55 studies), electrical stimulation (n=38 studies), and constraint-induced movement (n=28 studies) therapies. Despite a large and growing body of research, intervention dose and sample size of included studies were often too small to detect clinically important effects. Furthermore, interventions remain focused on subacute stroke recovery with little change in recent decades. A united research agenda that establishes a clear biological understanding of timing, dose, and intervention type is needed to progress stroke recovery research. Prospective Register of Systematic Reviews ID: CRD42018019367/CRD42018111629.

Multidimensional Phase I Dose Ranging Trials for Stroke Recovery Interventions: Key Challenges and How to Address Them

Despite an increase in the amount of published stroke recovery research, interventions have failed to markedly affect the trajectory of recovery poststroke. We argue that early-phase research to systematically investigate dose is an important contributor to advance the science underpinning stroke recovery. In this article, we aim to (a) define the problem of insufficient use of a systematic approach to early-phase, multidimensional dose articulation research and (b) propose a solution that applies this approach to design a multidimensional phase I trial to identify the maximum tolerated dose (MTD). We put forward a design template as a decision support tool to increase knowledge of how to develop a phase I dose-ranging trial for nonpharmaceutical stroke recovery interventions. This solution has the potential to advance the development of efficacious stroke recovery interventions, which include activity-based rehabilitation interventions.

Advancing Stroke Recovery Through Improved Articulation of Nonpharmacological Intervention Dose

Dose articulation is a universal issue of intervention development and testing. In stroke recovery, dose of a nonpharmaceutical intervention appears to influence outcome but is often poorly reported. The challenges of articulating dose in nonpharmacological stroke recovery research include: (1) the absence of specific internationally agreed dose reporting guidelines; (2) inadequate conceptualization of dose, which is multidimensional; and (3) unclear and inconsistent terminology that incorporates the multiple dose dimensions. To address these challenges, we need a well-conceptualized and consistent approach to dose articulation that can be applied across stroke recovery domains to stimulate critical thinking about dose during intervention development, as well as promote reporting of planned intervention dose versus actually delivered dose. We followed the Design Research Paradigm to develop a framework that guides how to articulate dose, conceptualizes the multidimensional nature and systemic linkages between dose dimensions, and provides reference terminology for the field. Our framework recognizes that dose is multidimensional and comprised of a duration of days that contain individual sessions and episodes that can be active (time on task) or inactive (time off task), and each individual episode can be made up of information about length, intensity, and difficulty. Clinical utility of this framework was demonstrated via hypothetical application to preclinical and clinical domains of stroke recovery. The suitability of the framework to address dose articulation challenges was confirmed with an international expert advisory group. This novel framework provides a pathway for better articulation of nonpharmacological dose that will enable transparent and accurate description, implementation, monitoring, and reporting, in stroke recovery research.

Early-phase dose articulation trials are underutilized for post-stroke motor recovery: A systematic scoping review

BACKGROUND

To enable development of effective interventions, there is a need to complete systematic early-phase dose articulation research. This scoping review aimed to synthesize dose articulation research of behavioral motor interventions for stroke recovery.

METHODS

MEDLINE and EMBASE were systematically searched for dose articulation studies. Preclinical experiments and adult clinical trials were classified based on the discovery pipeline and analyzed to determine which dose dimensions were articulated (time, scheduling or intensity) and how they were investigated (unidimensional vs multidimensional approach). Reporting of dose, safety and efficacy outcomes were summarized. The intervention description, risk of bias, and quality was appraised.

RESULTS

We included 41 studies: 3 of preclinical dose preparation (93 rodents), 2 Phase I dose ranging (21 participants), 9 Phase IIA dose screening (198 participants), and 27 Phase IIB dose finding (1879 participants). All studies adopted a unidimensional approach. Time was the most frequent dimension investigated (53%), followed by intensity (29%), and scheduling (18%). Overall, 95% studies reported an efficacy outcome; however, only 65% reported dose and 45% reported safety. Across studies, 61% were at high risk of bias, and the average percentage reporting of intervention description and quality was 61% and 67%, respectively.

CONCLUSION

This review highlights a need to undertake more high-quality, early-phase studies that systematically articulate intervention doses from a multidimensional perspective in the field of behavioral motor stroke recovery. To address this gap, we need to invest in adapting early phase trial designs, especially Phase I, to support multidimensional dose articulation.

Dose effects in behavioural treatment of post-stroke aphasia: a systematic review and meta-analysis

PURPOSE

Aphasia is a debilitating chronic acquired language disorder that impacts heavily on a person's life. Behavioural treatments aim to remediate language processing skills or to enhance communication between the person with aphasia and others, and a number of different treatments are efficacious. However, it is unclear how much of a particular treatment a person needs in order to optimise recovery of language and communication skills following stroke.

MATERIALS AND METHODS

Systematic search for and meta-analysis of experimental studies that directly compared different amounts of the same behavioural aphasia treatment, following PRISMA guidelines.

RESULTS

Treatment dose research in aphasia is an emerging area. Just six studies comparing different doses of the same intervention met all criteria for inclusion. Evidence from these studies was synthesised and meta-analysed, where possible. Meta-analyses were inconclusive due to limited data; however, there are indications that suggest increased dose may confer greater improvement on language and communication measures, but with diminishing returns over time. Aphasia severity and chronicity may affect dose-response relationships.

CONCLUSIONS

There is currently insufficient evidence to determine the effect of dose on treatment response. A dedicated and coordinated research agenda is required to systematically explore dose-response relationships in post-stroke aphasia interventions.A video abstract is available in the Supplementary Material.Implications for rehabilitationThe investigation of the effect of dose on treatment outcomes in post-stroke aphasia is an emerging research area with few studies reporting comparison of different amounts of the same intervention.In the acute phase of recovery following stroke, higher doses of treatment provided over short periods may not be preferable, tolerable, or superior to lower doses of the same treatment.In the chronic phase, providing additional blocks of treatment may confer additional benefit for some people with aphasia but with diminishing returns.People with chronic aphasia can achieve and maintain significant gains in picture naming after a relatively brief period of high-dose treatment.

Treatment dose in post-stroke aphasia: A systematic scoping review

Little is known about how the amount of treatment a person with aphasia receives impacts aphasia recovery following stroke, yet this information is vital to ensure effective treatments are delivered efficiently. Furthermore, there is no standard dose terminology in the stroke rehabilitation or aphasia literature. This scoping review aims to systematically map the evidence regarding dose in treatments for post-stroke aphasia and to explore how treatment dose is conceptualized, measured and reported in the literature. A comprehensive search was undertaken in June 2019. One hundred and twelve intervention studies were reviewed. Treatment dose (amount of treatment) has been conceptualized as both a measure of time and a count of discrete therapeutic elements. Doses ranged from one to 100 hours, while some studies reported session doses of up to 420 therapeutic inputs per session. Studies employ a wide variety of treatment schedules (i.e., session dose, session frequency, and intervention duration) and the interaction of dose parameters may impact the dose-response relationship. High dose interventions delivered over short periods may improve treatment efficiency while maintaining efficacy. Person- and treatment-level factors that mediate tolerance of high dose interventions require further investigation. Systematic exploration of dose-response relationships in post-stroke aphasia treatment is required.

Poststroke Impairment and Recovery Are Predicted by Task-Specific Regionalization of Injury

Lesion size and location affect the magnitude of impairment and recovery following stroke, but the precise relationship between these variables and functional outcome is unknown. Herein, we systematically varied the size of strokes in motor cortex and surrounding regions to assess effects on impairment and recovery of function. Female Sprague Dawley rats (N = 64) were evaluated for skilled reaching, spontaneous limb use, and limb placement over a 7 week period after stroke. Exploration and reaching were also tested in a free ranging, more naturalistic, environment. MRI voxel-based analysis of injury volume and its likelihood of including the caudal forelimb area (CFA), rostral forelimb area (RFA), hindlimb (HL) cortex (based on intracranial microstimulation), or their bordering regions were related to both impairment and recovery. Severity of impairment on each task was best predicted by injury in unique regions: impaired reaching, by damage in voxels encompassing CFA/RFA; hindlimb placement, by damage in HL; and spontaneous forelimb use, by damage in CFA. An entirely different set of voxels predicted recovery of function: damage lateral to RFA reduced recovery of reaching, damage medial to HL reduced recovery of hindlimb placing, and damage lateral to CFA reduced recovery of spontaneous limb use. Precise lesion location is an important, but heretofore relatively neglected, prognostic factor in both preclinical and clinical stroke studies, especially those using region-specific therapies, such as transcranial magnetic stimulation.SIGNIFICANCE STATEMENT By estimating lesion location relative to cortical motor representations, we established the relationship between individualized lesion location, and functional impairment and recovery in reaching/grasping, spontaneous limb use, and hindlimb placement during walking. We confirmed that stroke results in impairments to specific motor domains linked to the damaged cortical subregion and that damage encroaching on adjacent regions reduces the ability to recover from initial lesion-induced impairments. Each motor domain encompasses unique brain regions that are most associated with recovery and likely represent targets where beneficial reorganization is taking place. Future clinical trials should use individualized therapies (e.g., transcranial magnetic stimulation, intracerebral stem/progenitor cells) that consider precise lesion location and the specific functional impairments of each subject since these variables can markedly affect therapeutic efficacy.

Elizabeth Usher Memorial Lecture: Lost in Translation? Challenges and future prospects for a neurobiological approach to aphasia rehabilitation

While there has been considerable progress in conducting trials of aphasia therapy, there is no consistent evidence for long-term benefits of aphasia treatment, suggesting the need to reconsider current approaches. There are also no accurate methods for determining the amount, type and timing of aphasia therapy that should be provided for an individual. At the same time, there has been increasing interest in applying various principles of neuroplasticity to aphasia treatment and using measures of brain structure and function to predict recovery. This article will consider the potential of neuroplasticity principles and neurobiological predictors to improve our current approach to aphasia rehabilitation and optimise outcomes. Reviewing these principles highlights some of the challenges of translating animal model-based principles and emphases the need to also consider relevant theories of human learning. While considerable progress has been made in considering neurobiological principles and using measures of brain structure and function to predict recovery, there is significant work required to achieve the full potential of this neurobiological approach to aphasia management.