Introduction to Special Issue on Outcome Measures for IDD: Where We Have Been, Where We Are Now, and Where We Are Heading.

03Original abstract

Assessment is all around us. From the beginning of what we know of modern history, there have been efforts to use data on individual differences to sort, diagnose, monitor, predict, enlighten, and—in the case of glossy magazine quizzes—even entertain. Yet, in many cases, assessment tools that are readily available for the masses miss the mark for the intended few who need them most. This has certainly been the case over the course of clinical trials for people with intellectual and developmental disabilities (IDDs), a collection of conditions characterized by intellectual disability and adaptive behavior support needs (American Psychiatric Association, 2013; Schalock et al., 2010). The intent of this special issue on outcome measures in IDD is to capture the current state of the science—including recent advances—as a means to identify key themes and gaps that can move the field forward. Here, in our introduction to this special issue, we highlight some of the impetus for this work and what we learned as we brought this special issue together.The need for valid and reliable outcome measures for IDD has been highlighted by the recent dilemmas of clinical trial researchers who have repeatedly reported difficulties detecting change in IDD research participants over the course of interventions. Although a failure to detect change may in some cases indicate that change did not, in fact, take place, the field has increasingly recognized that a portion of these failures is likely attributable to the limited repertoire of outcome measures available to people with IDD (e.g., Budimirovic et al., 2017; Erickson et al., 2017). In March of 2019, we hosted a working group to discuss these issues at the Gatlinburg Conference for Intellectual and Developmental Disabilities in San Antonio, TX. What we anticipated to be an intimate meeting of a handful of interested researchers quickly ballooned into a team of over 45 researchers from the United States and United Kingdom, including individuals representing a variety of institution types, disciplines, and ranks. As we repeatedly called on hotel staff to bring in more chairs, it became clear to us that an energy surrounds the issue of outcome measures in IDD, even nearly a decade after the National Institutes of Health (NIH) released its first request for application (RFA) specific to the topic (PAR-11-045).In this special issue, we feature a selection of double-blind peer-reviewed articles authored by some of the leading voices in neurodevelopmental disability research, tasked with tackling the challenges associated with assessment tools and outcome measures for individuals with IDD. The articles highlight a variety of novel approaches to measuring changes in symptoms for individuals with IDD, including standardizing adaptations and scoring metrics for existing measures (DiStefano et al; Farmer et al.), use of psychophysiological biomarkers such as event-related potentials (ERPs; Berry-Kravis et al.; Key et al), and development and validation of targeted instruments specific to the IDD population (Brady et al., Raspa et al.).Before we look at the present work, however, it is well worth considering the historic path that brought us to the current state of clinical trials in IDDs. Figure 1 depicts a timeline illustrating a select handful of critical guideposts that marked or signaled changes in the field of IDD clinical trials. As the timeline reflects, the history of clinical trials in IDDs—and the development of outcome measures for use in those trials—reflects complex interactions across civil rights movements, parent organizations, federal legislation, and scientific and technological advances. The timeline also highlights forward motion in social justice and inclusion for people with IDDs, from the deinstitutionalization sparked by the Willowbrook exposé to the countless syndrome-specific organizations, largely founded by parents and caregivers, now seeking to optimize outcomes for people with IDDs and their families.This brings us to the present and helps to underscore the importance of articles in this special issue. Thurm et al. ask the question as to why the core symptoms of intellectual disability—impairment in cognitive and functional skills—are not considered primary targets for clinical trials. By way of describing this phenomenon, this article provides an overview of challenges associated with use of measures that address core symptoms of IDD along with potential solutions for the field, especially those designing clinical trials for disease-modifying treatments, to consider. DeStefano et al. similarly describe the challenges associated with providing high-quality, accurate assessments of individuals with severe and profound IDD, offering a set of guidelines for standardizing protocols across clinicians and researchers.Two strategies described in these review articles and illustrated in articles throughout this special issue include the development and testing of new, novel objective biomarkers, and targeting psychometrics for instruments specific to populations of individuals with IDD. Promising potential biomarkers are described in Berry-Kravis et al. and Key et al. Specifically, Berry-Kravis et al. describe measuring ERP during an auditory oddball paradigm to successfully assess neural correlates of sensory processing in fragile X syndrome. Key et al. describe the benefits and challenges of using ERP and eye tracking as objective measures of receptive language processing. These two articles exemplify the promise of psychophysiological measures as tools for assessing traditionally hard to assess populations and/or hard to assess domains of functioning.Rigorous testing of measures or scoring procedures that have been designed to assess target skills or behaviors in IDD populations is another strategy for addressing the gap in outcome measures for this population. Three articles in the special issue address this strategy. Farmer et al. describes the use of ability scores, as opposed to standard scores, as a mechanism for monitoring change over time or in response to a treatment. Two studies are described to illustrate this strategy, demonstrating the utility of ability scores to assess change on the Vineland-3rd edition and the Differential Ability Scale, 2nd edition. In Brady et al. the Communication Complexity Scale (CCS) is tested as a sensitive measure to assess change in children who are preverbal or have very early verbal communication skills. This study demonstrates that the CCS is sensitive to change in children participating in a behavioral intervention to improve communication, offering further evidence for this tool as a valid and reliable measure of communication change. Finally, in Raspa et al., the psychometric properties of the Motor-Behavior Assessment are explored for use in trials focusing on Rett syndrome.The articles in this special issue illustrate the significant progress the field has made in considering the unique needs and challenges associated with assessment of individuals with IDD. However, recent events highlight the need to recognize not only how the history of our field shapes our current context, but also how current events are shaping the next phase of our science in outcome measure development. Since our initial meeting about this special issue at the Gatlinburg Conference, the global landscape of clinical science has rapidly shifted in response to the COVID-19 pandemic. Now, outcome measures must not only be valid, reliable, and sensitive to change, but they also must—in some cases—be able to be administered remotely, or with little face-to-face contact. Moving forward, we must continue to critically evaluate the degree to which administering outcome measures remotely may alter their standardization and psychometric rigor. New techniques may be needed to facilitate use of outcome measures such as use of ERPs and eye tracking throughout the pandemic and beyond. And of course, given the higher risks associated with COVID-19 within populations of people with IDD (Turk et al., 2020), we must be attuned to the lived experiences of our participants and their families—beyond our current study—as we try to understand their development and needs.These issues also critically intersect with broader representation and access in IDD clinical trials, including racial health disparities that continue to plague our field. It is well established that underrepresentation of Black and minority families in clinical research is a pervasive injustice and threatens the validity and generalizability of findings. The underrepresentation of minority families in assessment research likely skews measures to best assess development in majority populations, potentially contributing to sobering statistics of delayed diagnoses and lower quality treatment in minority individuals with IDDs (e.g., Cook et al., 2017; Mandell et al., 2009). The impact of these injustices may range from minor inaccuracies in scores to major alterations in quality of life or safety—such as in the case of special education eligibility determination, or perhaps lethal decision making during criminal trial proceedings. Beyond the validity of the tests themselves, minority families are less likely to engage in research studies, in part due to mistrust of medical research, seeded in historic and egregious mistreatment of Black and minority families in trials such as the Tuskegee syphilis study (Figure 1), as well as current pervasiveness of racism and discrimination in medical settings (Scharff et al., 2010). Whereas small samples and challenging recruitment in IDD clinical research have, in some ways, prepared us for remote assessment during COVID-19, these same issues have likely stalled our progress in addressing racial health disparities and considering how underrepresentation critically flaws our science. Indeed, although filling a sample cohort with rare syndromes is an accomplishment in and of itself, critically evaluating the demographic composition of the cohort often takes a back seat. However, bringing these conversations to the forefront is critical. We also must ask ourselves some hard questions as we design our outcome measures. What could we do differently to reverse these patterns? What methodologies are we missing? Who is missing from decision-making tables? How do we move forward in ensuring the measures we design and use are appropriate for all?In conclusion, this special issue offers a snapshot of assessment progression at a dynamic and historic moment. We are encouraged by the wide range of approaches described in this corpus, as well as the ideas for forward movement expressed by the authors. The landscape of assessment in IDD is rapidly changing; as a community, we must continue to rise to these evolving challenges to support the best treatments and quality of life for individuals with IDD.We thank the Gatlinburg Conference organizers, Purdue University College of Health and Human Sciences, and Purdue University Department of Psychological Sciences for sponsoring the working group meeting that sparked the organization of this special issue. We also thank Dr. Frank Symons, AJIDD Editor, and the AJIDD editorial team for inviting us to guest edit this special issue, as well as for managing its execution in such tumultuous times. We also thank Dr. Audrey Thurm at the National Institute of Mental Health (NIMH) for her input on portions of this editorial.

American journal on intellectual and developmental disabilities, 2020 · doi:10.1352/1944-7558-125.6.413