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Objective To characterize the qualities that individuals with spinal cord injury (SCI) associate with their experience of spasticity and to describe the relationship between spasticity and perceived quality of life and the perceived value of spasticity management approaches. Design Online cross-sectional survey. Setting Multicenter collaboration among 6 Spinal Cord Injury Model Systems hospitals in the United States. Participants Individuals with SCI (N=1076). Interventions Not applicable. Main Outcome Measures Qualities of Spasticity Questionnaire, modified Spinal Cord Injury–Spasticity Evaluation Tool (mSCI-SET), and the modified Patient-Reported Impact of Spasticity Measure (mPRISM). Results Respondents indicated that spasms most often occurred in response to movement-related triggering events. However, spontaneous spasms (ie, no triggering event) were also reported to be among the most common types. Frequency of spasms appears to decline with age. The highest frequency of spasms was reported by 56% of respondents aged 55 years. Stiffness associated with spasticity was reported to be more common than spasms (legs, 65% vs 54%; trunk, 33% vs 18%; arms, 26% vs 15%). Respondents reported negative effects of spasticity more commonly than positive effects. Based on their association with negative scores on the mSCI-SET and the mPRISM, the 5 most problematic experiences reported were stiffness all day, interference with sleep, painful spasms, perceived link between spasticity and pain, and intensification of pain before a spasm. Respondents indicated spasticity was improved more by stretching (48%) and exercise (45%) than by antispasmodics (38%). Conclusions The experience of spasticity after SCI is complex and multidimensional, with consequences that affect mobility, sleep, comfort, and quality of life. Stiffness, rather than spasms, appears to be the most problematic characteristic of spasticity. Physical therapeutic interventions to treat spasticity warrant in-depth investigation.

Rehabilitation clinicians strive to provide cost-effective, patient-centered care that optimizes outcomes. A barrier to this ideal is the lack of a universal system for describing, or specifying, rehabilitation interventions. Current methods of description vary across disciplines and settings, creating barriers to collaboration, and tend to focus mostly on functional deficits and anticipated outcomes, obscuring connections between clinician behaviors and changes in functioning. The Rehabilitation Treatment Specification System (RTSS) is the result of more than a decade of effort by a multidisciplinary group of rehabilitation clinicians and researchers to develop a theory-based framework to specify rehabilitation interventions. The RTSS describes interventions for treatment components, which consist of a target (functional change brought about as a direct result of treatment), ingredients (actions taken by clinicians to change the target), and a hypothesized mechanism of action, as stated in a treatment theory. The RTSS makes explicit the connections between functional change and clinician behavior, and recognizes the role of patient effort in treatment implementation. In so doing, the RTSS supports clinicians' efforts to work with their patients to set achievable goals, select appropriate treatments, adjust treatment plans as needed, encourage patient participation in the treatment process, communicate with team members, and translate research findings to clinical care. The RTSS may help both expert and novice clinicians articulate their clinical reasoning processes in ways that benefit treatment planning and clinical education, and may improve the design of clinical documentation systems, leading to more effective justification and reimbursement for services. Interested clinicians are invited to apply the RTSS in their local settings.

The field of rehabilitation remains captive to the black-box problem: our inability to characterize treatments in a systematic fashion across diagnoses, settings, and disciplines, so as to identify and disseminate the active ingredients of those treatments. In this article, we describe the Rehabilitation Treatment Specification System (RTSS), by which any treatment employed in rehabilitation may be characterized, and ultimately classified according to shared properties, via the 3 elements of treatment theory: targets, ingredients, and (hypothesized) mechanisms of action. We discuss important concepts in the RTSS such as the distinction between treatments and treatment components, which consist of 1 target and its associated ingredients; and the distinction between targets, which are the direct effects of treatment, and aims, which are downstream or distal effects. The RTSS includes 3 groups of mutually exclusive treatment components: Organ Functions, Skills and Habits, and Representations. The last of these comprises not only thoughts and feelings, but also internal representations underlying volitional action; the RTSS addresses the concept of volition (effort) as a critical element for many rehabilitation treatments. We have developed an algorithm for treatment specification which is illustrated and described in brief. The RTSS stands to benefit the field in numerous ways by supplying a coherent, theory-based framework encompassing all rehabilitation treatments. Using a common framework, researchers will be able to test systematically the effects of specific ingredients on specific targets; and their work will be more readily replicated and translated into clinical practice.

Despite significant advances in measuring the outcomes of rehabilitation interventions, little progress has been made in specifying the therapeutic ingredients and processes that cause the measured changes in patient functioning. The general approach to better clarifying the process of treatment has been to develop reporting checklists and guidelines that increase the amount of detail reported. However, without a framework instructing researchers in how to describe their treatment protocols in a manner useful to or even interpretable by others, requests for more detail will fail to improve our understanding of the therapeutic process. In this paper, we describe how the Rehabilitation Treatment Specification System (RTSS) provides a theoretical framework that can improve research intervention reporting and enable testing and refinement of a protocol’s underlying treatment theories. The RTSS framework provides guidance for researchers to explicitly state their hypothesized active ingredients and targets of treatment; as well as how the individual ingredients in their doses directly affect the treatment targets. We explain how theory-based treatment specification has advantages over checklist approaches for intervention design, reporting, replication, and synthesis of evidence in rehabilitation research. A complex rehabilitation intervention is used as a concrete example of the differences between an RTSS-based specification and the Template for Intervention Description and Replication (TIDieR) checklist. The RTSS’s potential to advance the rehabilitation field can be empirically tested through efforts to use the framework with existing and newly developed treatment protocols.

Most rehabilitation treatments are volitional in nature, meaning that they require the patient's active engagement and effort. Volitional treatments are particularly challenging to define in a standardized fashion, because the clinician is not in complete control of the patient's role in enacting these treatments. Current recommendations for describing treatments in research reports fail to distinguish between 2 fundamentally different aspects of treatment design: the selection of treatment ingredients to produce the desired functional change and the selection of ingredients that will ensure the patient's volitional performance. The Rehabilitation Treatment Specification System (RTSS) is a conceptual scheme for standardizing the way that rehabilitation treatments are defined by all disciplines across all areas of rehabilitation. The RTSS highlights the importance of volitional behavior in many treatment areas and provides specific guidance for how volitional treatments should be specified. In doing so, it suggests important crosscutting research questions about the nature of volitional behavior, factors that make it more or less likely to occur, and ingredients that are most effective in ensuring that patients perform desired treatment activities.

Objective To describe group therapy utilization in spinal cord injury (SCI) inpatient rehabilitation. Design Prospective observational study. Setting Six inpatient rehabilitation facilities. Participants Patients (N=1376) receiving initial rehabilitation after traumatic SCI. Interventions Not applicable. Main Outcome Measure Time spent in group versus individual therapy for physical therapy (PT), occupational therapy (OT), therapeutic recreation (TR), and psychology (PSY) therapies. Results The majority (98%) of patients participated in at least 1 group therapy session, with 83%, 81%, 80%, and 54% of patients receiving group PT, OT, TR, and PSY, respectively. On average, 24% of treatment sessions and 27% of treatment time was provided in group sessions, with TR providing the greatest percent of its time in groups. Group therapy time and time spent in specific activities varied among patient subgroups with different injury characteristics. Group therapy time also varied widely among centers (range, 1.2–6.6h/wk). Across all injury subgroups, individual and group therapy hours per week were negatively correlated for OT and positively correlated for TR. Patient characteristics, clinician experience, and treatment center predicted 32% of variance in group hours per week. PT and OT strengthening/endurance interventions and TR outings were the most common group activities overall. Conclusions While the majority of inpatient SCI rehabilitation consists of individual sessions, most patients participate in group therapy, which contributes significantly to total therapy time. Patterns of group utilization fit with functional expectations and clinical goals. A trade-off between group and individual therapy may occur in some disciplines. Utilization of group therapy varies widely among centers, and further study is needed to identify optimal patterns of group therapy utilization.

Jette AM, Tulsky DS, Ni P, Kisala PA, Slavin MD, Dijkers MP, Heinemann AW, Tate DG, Whiteneck G, Charlifue S, Houlihan B, Williams S, Kirshblum S, Dyson-Hudson T, Zanca J, Fyffe D. Development and initial evaluation of the Spinal Cord Injury-Functional Index. Objectives To describe the calibration of the Spinal Cord Injury-Functional Index (SCI-FI) and report on the initial psychometric evaluation of the SCI-FI scales in each content domain. Design Cross-sectional survey followed by calibration data simulations. Setting Inpatient and community settings. Participants A sample of participants (N=855) with traumatic spinal cord injury (SCI) recruited from 6 SCI Model Systems and stratified by diagnosis, severity, and time since injury. Interventions None. Main Outcome Measure SCI-FI instrument. Results Item response theory analyses confirmed the unidimensionality of 5 SCI-FI scales: basic mobility (54 items), fine motor function (36 items), self-care (90 items), ambulation (39 items), and wheelchair mobility (56 items). All SCI-FI scales revealed strong psychometric properties. High correlations of scores on simulated computer adaptive testing (CAT) with the overall SCI-FI domain scores indicated excellent potential for CAT to accurately characterize functional profiles of adults with SCI. Overall, there was very little loss of measurement reliability or precision using CAT compared with the full item bank; however, there was some loss of reliability and precision at the lower and upper ranges of each scale, corresponding to regions where there were few questions in the item banks. Conclusions Initial evaluation revealed that the SCI-FI achieved considerable breadth of coverage in each content domain and demonstrated acceptable psychometric properties. The use of CAT to administer the SCI-FI will minimize assessment burden, while allowing for the comprehensive assessment of the functional abilities of adults with SCI.

Whiteneck GG, Gassaway J, Dijkers MP, Lammertse DP, Hammond F, Heinemann AW, Backus D, Charlifue S, Ballard PH, Zanca JM. Inpatient and postdischarge rehabilitation services provided in the first year after spinal cord injury: findings from the SCIRehab study. Objective To examine the amount and type of therapy services received in inpatient and postdischarge settings during the first year after spinal cord injury (SCI). Design Prospective observational longitudinal cohort design. Data were obtained from systematic recording of interventions by clinicians and from patient interview. Setting Inpatient and postdischarge rehabilitation programs. Participants Patients (N=493) with traumatic SCI admitted to 6 rehabilitation centers participating in the SCIRehab study. Interventions Not applicable. Main Outcome Measures Hours of therapy by physical therapy (PT), occupational therapy (OT), speech therapy, recreation therapy, psychology, social work/case management, and nursing education during initial inpatient rehabilitation and postdischarge up to the first anniversary of injury. Inpatient data were collected prospectively by the treating clinicians; postdischarge service data were collected by patient self-report during follow-up interviews. Results Of the total hours spent on these rehabilitation interventions during the first year after injury, 44% occurred after discharge from inpatient rehabilitation. Participants received 56% of their PT hours after discharge and 52% of their OT hours, but only a minority received any postdischarge services from other rehabilitation disciplines. While wide variation was found in the total hours of inpatient treatment across all disciplines, the variation in the total hours of postdischarge services was greater, with the interquartile range of postdischarge services being twice that of the inpatient services. Conclusions SCI rehabilitation is often given in a care continuum, with inpatient rehabilitation being only the beginning. Reductions in inpatient SCI rehabilitation length of stay are well documented, but the postdischarge services that may replace some inpatient treatment appear to be greater than previously reported. The availability and impact of postdischarge care should be studied in greater detail to capture the wide array of postdischarge services and outcomes.

With funding from a cooperative agreement from the National Institute on Disability and Rehabilitation Research, we have worked for the past 5 years on the development of a rehabilitation treatment taxonomy, a system of classifying all treatments delivered by all rehabilitation disciplines for all diagnostic groups of patients, whatever the setting in which these services are delivered. To date, we have focused on developing a conceptual framework for such a taxonomy, specifying the scope of the taxonomy and the basis for classifying treatments. A recent supplement of the Archives of Physical Medicine and Rehabilitation contained a series of articles setting forth the background for the project, our approach to conceptual issues, and the need to classify treatments based on a theory of how active ingredients bring about change in a clinical target of treatment (some aspect of patient functioning) through a specific mechanism of action.1 It also contains papers on how therapists view classification and lessons learned during a previous effort at classifying learning interventions, as well as commentaries by various scholars who had an opportunity to review these papers. Here we summarize the key points. The field of rehabilitation has made substantial advances in defining and measuring the functional outcomes of the rehabilitation process and the patient characteristics that are associated with those outcomes. However, we lack a rigorous and shared approach to defining, classifying, and measuring the rehabilitation treatments that are hypothesized to moderate the relationships between patient factors and outcomes. At present, rehabilitation treatments may be described as number …

In relation to the conceptual framework for a rehabilitation treatment taxonomy (RTT), which has been proposed in other articles in this supplement, this article discusses a number of issues relevant to its further development, including creating distinctions within the major target classes; the nature and quantity of allowable targets of treatment; and bracketing as a way of specifying (1) the skill or knowledge taught; (2) the nature of compensation afforded by changes in the environment, assistive technology, and orthotics/prosthetics; and (3) the ingredients in homework a clinician assigns. Clarification is provided regarding the role of the International Classification of Functioning, Disability and Health, focusing a taxonomy on ingredients versus other observable aspects of treatment, and regarding our lack of knowledge and its impact on taxonomy development. Finally, this article discusses the immediate implications of the work to date and presents the need for rehabilitation stakeholders of all disciplines to be involved in further RTT development.

Objective To determine rates of rehospitalization among discharged rehabilitation patients with traumatic spinal cord injury (SCI) in the first 12 months postinjury, and to identify factors associated with rehospitalization. Design Prospective observational cohort study. Setting Six geographically dispersed rehabilitation centers in the U.S. Participants Consecutively enrolled individuals with new traumatic SCI (N=951), who were discharged from participating rehabilitation centers and participated in a 1-year follow-up survey. Interventions Not applicable. Main Outcome Measures Occurrence of postrehabilitation rehospitalization within 1 year of injury, length of rehospitalization stays, and causes of rehospitalizations. Results More than one third (36.2%) of participants were rehospitalized at least once in the 12-month follow-up period; 12.5% were rehospitalized at least twice. The average number of rehospitalizations among those rehospitalized at least once was 1.37 times, with an average length of stay (LOS) of 15.5 days across all rehospitalization episodes. The 3 most common health conditions associated with rehospitalization were those related to the genitourinary system (eg, urinary tract infection), respiratory system (eg, pneumonia), and skin and subcutaneous tissue (eg, pressure ulcer). Being a woman (95% confidence interval [CI], 1.034–2.279), having Medicaid as the main payer (95% CI, 1.303–2.936), and more severe case mix were associated with increased odds of rehospitalization. Those who had more intensive physical therapy (95% CI, .960–.981) had lower odds of rehospitalization. Some center-to-center variation in rehospitalization rates remained unexplained after case mix and practice differences were considered. The 6 SCI rehabilitation centers varied nearly 2-fold in rates at which their former SCI patients were rehospitalized—from 27.8% to 50%. Center-to-center variation diminished when patient case mix was considered. Conclusions Compared with earlier studies, rehospitalization rates among individuals with SCI in the first postinjury year remain high and vary by level and completeness of injury. Rehospitalization risk was associated with younger age, being a woman, unemployment and retirement, and Medicaid coverage. Those who had more intensive physical therapy had lower odds of rehospitalization. Future studies should examine center-to-center variations in rehospitalization rates and availability of patient education and community resources.

Objective To describe pain during inpatient rehabilitation and its impact on delivery of inpatient rehabilitation services for persons with spinal cord injury (SCI). Design Prospective observational study and retrospective chart review. Setting Six inpatient rehabilitation facilities participating in the SCIRehab Study. Participants Patients (N=1357) receiving initial rehabilitation after traumatic SCI, for whom pain data were available. Interventions Not applicable. Main Outcome Measures Self-reported rating of pain intensity (0–10), pain locations, and treatment time by various rehabilitation disciplines. Results The vast majority of patients (97%) reported pain at least once during the rehabilitation stay, with an average pain intensity ± SD of 4.9±2.4. Average pain intensity over the stay was severe (rated 7–10) for 30% of patients, moderate (4–6) for 42%, and mild (1–3) for 25%. Pain prevalence at admission was greater than at discharge (87% vs 74%), as was pain intensity (6.0 vs 4.6). Most (79%) of the 177 participants who did not have pain at admission reported pain at least once later in the rehabilitation stay, but their average high pain intensity over the stay was lower than that of the full sample (1.9 vs 4.9). Nearly half (47%) of patients reported pain at ≥3 locations during the stay, with the back, neck, and shoulder commonly reported. Patients with severe pain spent fewer days in rehabilitation, received less rehabilitation treatment time (hours per week and total hours), and had more treatment sessions altered in objective or content because of pain than those with lower pain levels. Conclusions Pain is a common problem for persons receiving inpatient rehabilitation for traumatic SCI and adversely impacts delivery of therapy services.

Objective To describe therapist-reported factors affecting therapy sessions in spinal cord injury (SCI) inpatient rehabilitation and explore their impact on the patient's rehabilitation program. Design Prospective observational longitudinal cohort design. Data were obtained from systematic recordings of interventions by clinicians and from medical record abstraction. Setting Six inpatient rehabilitation programs. Participants Patients (N=1376) with traumatic SCI admitted for initial rehabilitation. Interventions Not applicable. Main Outcome Measures Factors recorded as impacting the objective or content of treatment sessions by physical therapy, occupational therapy, speech therapy, and therapeutic recreation, patients' participation in treatment as rated using a modified Pittsburgh Rehabilitation Participation Scale (PRPS), length of stay (LOS), medical morbidity measured using the Comprehensive Severity Index, hours of therapy per week, and missed therapy minutes. Results Patients received 151,172 treatment sessions from 483 therapists. Pain, fatigue, and spasticity were commonly reported factors; other medical, behavioral, and logistical factors were also frequent, with 30% of sessions being affected by at least 1 factor. The number of factors was correlated with missed therapy minutes and with the PRPS score. Patients with more reported factors, overall or per average session, had a longer LOS and fewer hours of treatment per week. Conclusions Medical and other factors complicating therapy are common. Those who need a longer stay because of their injury level or for other reasons have more opportunity to have sessions affected, but having many treatment sessions impacted by 1 or more factors also is likely to increase LOS. The nature of these factors and their impact on rehabilitation processes and outcomes deserve further study.

Tulsky DS, Jette AM, Kisala PA, Kalpakjian C, Dijkers MP, Whiteneck G, Ni P, Kirshblum S, Charlifue S, Heinemann AW, Forchheimer M, Slavin MD, Houlihan B, Tate DG, Dyson-Hudson T, Fyffe D, Williams S, Zanca J. Spinal Cord Injury-Functional Index: item banks to measure physical functioning in individuals with spinal cord injury. Objectives To develop a comprehensive set of patient-reported items to assess multiple aspects of physical functioning relevant to the lives of people with spinal cord injury (SCI), and to evaluate the underlying structure of physical functioning. Design Cross-sectional. Setting Inpatient and community. Participants Item pools of physical functioning were developed, refined, and field tested in a large sample of individuals (N=855) with traumatic SCI stratified by diagnosis, severity, and time since injury. Interventions None. Main Outcome Measure Spinal Cord Injury-Functional Index (SCI-FI) measurement system. Results Confirmatory factor analysis (CFA) indicated that a 5-factor model, including basic mobility, ambulation, wheelchair mobility, self-care, and fine motor function, had the best model fit and was most closely aligned conceptually with feedback received from individuals with SCI and SCI clinicians. When just the items making up basic mobility were tested in CFA, the fit statistics indicated strong support for a unidimensional model. Similar results were demonstrated for each of the other 4 factors, indicating unidimensional models. Conclusions Though unidimensional or 2-factor (mobility and upper extremity) models of physical functioning make up outcomes measures in the general population, the underlying structure of physical function in SCI is more complex. A 5-factor solution allows for comprehensive assessment of key domain areas of physical functioning. These results informed the structure and development of the SCI-FI measurement system of physical functioning.

Background Inpatient rehabilitation for spinal cord injury (SCI) includes the use of both individual and group physical therapy sessions. A greater understanding of group physical therapy use will help in the evaluation of the appropriateness of its use and contribute to the development of standards of practice. Objective This report describes the extent to which group physical therapy is being used in inpatient rehabilitation for SCI, identifies group physical therapy interventions being delivered, and examines patterns in the types of activities being used for people with different levels and completeness of injury (ie, injury groups). Design The SCIRehab Study is a 5-year, multicenter investigation that uses practice-based evidence research methodology. Methods Data on characteristics of participants and treatments provided were collected through detailed chart review and customized research documentation completed by clinicians at the point of care. The analyses described here included data from 600 participants enrolled during the first year of the project. Results Most of the participants (549/600) spent time in group physical therapy, and 23% of all documented physical therapy time was spent in group sessions. The most common group physical therapy activities were strengthening, manual wheelchair mobility, gait training, endurance activities, and range of motion/stretching. Time spent in group physical therapy and the nature of activities performed varied among the injury groups. Limitations Physical therapy use patterns observed in the 6 participating centers may not represent all facilities providing inpatient rehabilitation for SCI. Research documentation did not include all factors that may affect group physical therapy use, and some sessions were not documented. Conclusions The majority of physical therapy was provided in individual sessions, but group physical therapy contributed significantly to total physical therapy time. Group physical therapy time and activities differed among the injury groups in patterns consistent with clinical goals.

Objectives To describe the amount and content of group therapies provided during inpatient rehabilitation for traumatic brain injury (TBI), and to assess the relations of group therapy with patient, injury, and treatment factors and outcomes. Design Prospective observational cohort. Setting Inpatient rehabilitation. Participants Consecutive admissions (N=2130) for initial TBI rehabilitation at 10 inpatient rehabilitation facilities (9 in the United States, 1 in Canada) from October 2008 to September 2011. Interventions Not applicable. Main Outcome Measures Proportion of sessions that were group therapy (≥2 patients were treated simultaneously by ≥1 clinician); proportion of patients receiving group therapy; type of activity performed and amount of time spent in group therapy, by discipline; rehabilitation length of stay; discharge location; and FIM cognitive and motor scores at discharge. Results Of the patients, 79% received at least 1 session of group therapy, with group therapy accounting for 13.7% of all therapy sessions and 15.8% of therapy hours. On average, patients spent 2.9h/wk in group therapy. The greatest proportion of treatment time in group format was in therapeutic recreation (25.6%), followed by speech therapy (16.2%), occupational therapy (10.4%), psychology (8.1%), and physical therapy (7.9%). Group therapy time and type of treatment activities varied among admission FIM cognitive subgroups and treatment sites. Several factors appear to be predictive of receiving group therapy, with the treatment site being a major influence. However, group therapy as a whole offered little explanation of differences in the outcomes studied. Conclusions Group therapy is commonly used in TBI rehabilitation, to varying degrees among disciplines, sites, and cognitive impairment subgroups. Various therapeutic activities take place in group therapy, indicating its perceived value in addressing many domains of functioning. Variation in outcomes is not explained well by overall percentage of therapy time delivered in groups.

Objective To gain an understanding of clinical thought processes about treatment classification and description, and to identify desired characteristics of and challenges to be addressed by a future rehabilitation treatment taxonomy. Design Qualitative analysis of data collected via focus groups and semistructured interviews. Setting Inpatient rehabilitation programs. Participants Clinicians (N=84) in 7 disciplines involved in data collection for practice-based evidence studies of spinal cord injury and traumatic brain injury rehabilitation. Interventions Not applicable. Main Outcome Measure Summary of themes reported by clinicians, determined by content analysis of focus group and interview transcripts. Results The multifaceted nature of rehabilitation treatment was identified as a major challenge to the process of classifying interventions. Simultaneous delivery of multiple interventions, performance of integrated tasks that challenge multiple body systems, and conversation-based treatments were reported to be difficult to classify. Clinicians reported that treatment classifications that make reference to goals of treatment were clinically intuitive, but they also reported difficulties when attempting to classify activities that could address multiple goals. These rehabilitation practitioners considered the setting in which treatment occurs, equipment used, assistance or cueing provided, type of treatment participants, and specific tasks performed to be important descriptors of their interventions. They recommended creating a classification system that can be applied at greater or lesser levels of detail depending on the purpose for which it is being used. Conclusions Treatment descriptors identified may be useful for differentiating classes of treatments or characterizing treatments within classes. Precise definition of the concept of the goal as it relates to treatment theory and definition of boundaries between treatments may aid classification of multifaceted treatment activities. A balance between detail and feasibility of use will facilitate successful clinical application of a future classification system.

Rehabilitation is in need of an organized system or taxonomy for classifying treatments to aid in research, practice, training, and interdisciplinary communication. In this article, we describe a work-in-progress effort to create a rehabilitation treatment taxonomy (RTT) for classifying rehabilitation interventions by the underlying treatment theories that explain their effects. In the RTT, treatments are grouped together according to their targets, or measurable aspects of functioning they are intended to change; ingredients, or measurable clinician decisions and behaviors responsible for effecting changes; and the hypothesized mechanisms of action by which ingredients are transformed into changes in the target. Four treatment groupings are proposed: structural tissue properties, organ functions, skilled performances, and cognitive/affective representations, which are similar in the types of targets addressed, ingredients used, and mechanisms of action that account for change. The typical ingredients and examples of clinical treatments associated with each of these groupings are explored, and the challenges of further subdivision are discussed. Although a Linnaean hierarchical tree structure was envisioned at the outset of work on the RTT, further development may necessitate a model with less rigid boundaries between classification groups, and/or a matrix-like structure for organizing active ingredients along selected continua, to allow for both qualitative and quantitative variations of importance to treatment effects.