Dosage Parameters in Pediatric Outcome Studies Reported in 9 Peer-Reviewed Occupational Therapy Journals from 2008 to 2014: A Content Analysis

Occupational therapists determine the dosage when establishing the plan of care for their pediatric clients. A content analysis was conducted using 123 pediatric occupational therapy outcomes studies from 9 scholarly international occupational therapy journals. The parameters of dosage were calculated using descriptive statistics in order to obtain a representation of dosage available within the current collage of pediatric occupational therapy outcomes studies. The results revealed that most studies reported portions of dosage parameters within the published studies. The average findings for the subcomponents related to dosage were session length (minutes) M = 58.7, duration of plan of care (weeks) M = 12.1, session frequency (per week) M = 3.4, and total hours of therapy (hours) M = 18.1. This first attempt at describing and calculating dosage related to pediatric occupational therapy practice indicates that evidence is lacking within the published literature to adequately guide OT dosage decisions. Further research related to dosage in pediatric occupational therapy practice is needed.


Introduction
Occupational therapists (OTs) determine the intervention dosage when establishing the plan of care for their pediatric clients as a part of the routine occupational therapy process [1]. The dosage selected for the provision of occupational therapy services is likely to influence the overall effectiveness of the intervention provided [2]. Published research literature may provide evidence to guide the choices of OTs when making dosage decisions in order to achieve the best possible outcomes for the most reasonable cost. However, it is not currently known how prevalent published research is that includes data regarding parameters and decision making towards intervention dosage.
Dosage may be defined as the combination of the frequency of treatment sessions, intensity of the intervention provided, duration of the episode of care, and the type of intervention or interventions applied [2][3][4]. The combination of these parameters of dosage likely interact to produce the outcome achieved. Research addressing different combinations of frequency, intensity, and duration for a particular intervention or combination of interventions would provide valuable evidence to guide the choices of OTs when making dosage decisions in pediatric clinical practice.
There are multiple influences that could impact an OTs choice of dosage when establishing the plan of care for a pediatric client. In addition to the evidence available within the research literature, an OTs choice of dosage could be influenced by client factors (medical diagnosis, age, client/family/care provider goals, etc.) [3], practice setting dynamics (setting type such as school or outpatient, scheduling logistics, colleagues' choices) [5,6] reimbursement (restrictions on the number of visits funded by insurance) [7], and the choice of interventions. Research is needed to identify and better understand the process OTs use to select the dosage for a client's plan of care and which factors influence dosage decisions the most.

Rehabilitation Research and Practice
A search of PubMed, Ovid, and CINAHL of the published literature for the previous 15 years revealed only one published article describing decision making of dosage for outcomes following provision of physical therapy and occupational therapy services for adult clients [8]. No literature was found describing the relationship between dosage and therapeutic outcome for physical therapy or occupational therapy interventions for the decision making for pediatric clients. Within the published literature, there is inconsistent reporting of frequency, duration, and intensity of services provided, with an apparent emphasis on the type of intervention used. The lack of evidence to support dosage decisions requires the reader to infer potential influences of different components of dosage, often with incomplete information.
Research is needed to fill the gap in the literature regarding the components and parameters of dosage decisions in occupational therapy research and practice and how they influence the provision of service for pediatric populations.
The purpose of this study was to ascertain the dosage parameters included in published outcome studies related to pediatric occupational therapy practice in key occupational therapy journals between the years 2008 and 2014. The guiding research question for this study was the following: How frequently are dosage parameters published in pediatric OT outcome studies? Our hypotheses were as follows: (1) Dosage parameters will be included within published OT outcome studies addressing pediatric interventions and (2) the current literature will include more outcome studies with partial than complete dosage parameters. A focused content analysis of recently published research literature identified the breadth and depth of the evidence available to inform an OTs dosage decisions for pediatric clients. The information provided by this study may indicate how available evidence is for guiding dosage decisions in pediatric OT clinical practice and influence future research on the inclusion and investigation of dosage parameters.

Operational Definitions.
For consistency throughout the process of this content analysis, intervention was defined as "to assist the client in reaching a state of physical, mental, and social well-being; to identify and realize aspirations; to satisfy needs; and to change or cope with the environment" (AOTA, p. 652). Pediatric occupational therapy was defined as a scope of occupational therapy practice for children and youth (0-21 years old) who exhibit occupational performance deficits in the areas of work, leisure/play, social participation, activities of daily living/instrumental activities of daily living, and education [9,10]. Intervention frequency was defined as the number of treatment sessions (AOTA, 2006) and intervention duration was the length of the intervention plan [11][12][13]. Intervention intensity referred to the length of each intervention session (i.e., 60 minutes) and the type of service delivery (i.e., 1 : 1 or group) [12,[14][15][16][17]. Using a format of categorization and analysis exemplified by May-Benson and Koomar, [7] dosage was defined as including aspects related to an intervention's duration (weeks), sessions per week, minutes per session, treatment session length, and total therapy hours. Each category of dosage, if provided, was used as a metric of analysis.

Inclusion Criteria.
For this study published articles that reported quantitative, measurable outcomes for pediatric clients between birth to 21 years of age were included in the initial review. In addition, articles had to report on occupational therapy interventions that fell within the Occupational Therapy Practice Framework: 3rd Edition (OTPF) and targeted pediatric clients, their teachers, caregivers, and/or parents. Furthermore, to be included in the review, articles must have stated at least one or more of the parameters regarding the frequency, intensity, and/or duration of the intervention tested as defined previously. Articles published between 2008 and 2014 in one of the following occupational therapy specific journals were considered for this study (see Table 1).

Exclusion Criteria.
For the purposes of this review, systematic reviews or qualitative studies were not included. In addition, articles published in nonoccupational therapy journals were excluded since they typically do not report their connection to the OTPF which may not focus on the interventions most relevant to occupational therapy. Articles were excluded if they did not report at least one of the parameters of frequency, intensity, or duration of therapy or if they measured nonintervention aspects of the occupational therapy process (i.e., evaluation tools).

Procedures.
A total of 123 outcome studies ultimately were included within the analysis and are listed in the Appendix. Two researchers and five graduate research assistants were assigned to screen the most current seven years (2008-2014) of each occupational therapy journal online via the journal's website. We read the abstract and methods section of each article in each journal reviewed (see Table 1) to determine if the article met all of the inclusion criteria. In the event that access to an article was unavailable through the Idaho State University library or other web-based resources, only the abstract was reviewed to determine if the inclusion and exclusion criteria were likely to be met and an interlibrary loan request was needed.
After all of the targeted journals were screened, the first review of each article was conducted and the following information was recorded: duration (weeks) of services, number of sessions per week, duration of each session (minutes), total therapy hours, type of delivery (1 : 1 or group), sample size, and level of evidence. A second reviewer analyzed the same information from each article and tracked the number of disagreements. Any disagreements were then discussed by the first and second reviewer. If the first and second reviewers were unable to come to an agreement, the issues were brought to the weekly meetings for all reviewers to discuss and resolve. Conflicts and final decisions were documented for each article.

Results
One hundred and twenty three articles were found meeting the inclusion criteria. The data gathered from the articles Rehabilitation Research and Practice 3  representing sample size and the dosage parameters were analyzed using descriptive statistics (mean, median, and standard deviation) (see Table 2). Overall the American Journal of Occupational Therapy yielded the most pediatric outcomes studies ( = 58) with the remaining eight journals containing 14 or fewer during the previous seven years (see Figure 1).
All of the articles that met the inclusion criteria reported the number of participants who participated in each study (see Table 2) and there was a large range of sample sizes represented. The reporting of other subcomponents ranged from 75 to 88% (percentage equals the total of articles divided by the of articles reporting specific dosage subcomponents) of the articles. The length of each treatment session was the most reported subcomponent and the total number of therapy hours received was the least frequently reported (see Table 2).

Discussion
The purpose of this content analysis of pediatric outcome studies focusing on dosage was to investigate the availability of evidence to guide OTs making decisions for intervention planning with pediatric clients. The results of this study indicate that the majority of published outcome studies in pediatric OT journals that include at least one dosage parameter also include an additional dosage parameter. However, not all of the parameters are available within every article. This finding suggests there is some evidence available to clinically practicing pediatric OTs regarding some of the parameters of dosage needed when developing the plan of care. It also suggests that OTs currently must rely on clinical experience when selecting dosage parameters that are not fully represented within the literature. Further research and more complete documentation of dosage parameters are needed to ensure that the results of outcome studies may be applied clinically in an effective manner.
The results of this study display a wide range of OT practice and research that suggests a high intensity and frequency of intervention over shorter periods of time is used in outcome studies of pediatric occupational therapy interventions. It is not known whether the dosage of these

Duration.
The duration of the plan of care was relatively frequently reported (86%) by the articles in this content review. Due to the heterogeneity of studies included in this review, the range of duration is substantial, spanning from 0.14 weeks to 96 weeks. The studies that were at the bottom and top end of the range and standard deviation for the duration of the length of plan of care in this content review may be heavily influenced by studies we labeled as "outliers." For example, one study by Bates [18] was a case report of a single child who received outpatient occupational therapy services for almost two years. Ryan et al. [19], on the other end of the reported range, reported a total length of intervention of 1 hour (0.14 weeks) provided in a single session.   Our analysis also included a comparison of the types of research and the level of evidence sourced in Portney and Watkins [24] (see Table 3, levels of evidence). The most common type of research design found within our review was Level IV (case series, single case) ( = 51) and the less frequently found was Level I (randomized control trials).

Current Discussions of Dosage.
Novak [25] stated that the core goal of evidenced based practice was for the therapist to "do the right things for the right client at the right time" (p. 1) in order to optimize therapeutic outcomes. Over the past several years the topic of therapeutic dosage has been brought up within the pediatric rehabilitation literature. A paucity of content related to dosage recommendations continues to plague pediatric practitioners. That being said, recent authors have attempted to address the topic of dosage through opinion pieces, the development of clinical pathways based upon medical/behavioral condition, or tiered decision scaffolds based upon the client's response to a given intervention. Palisono and Murr [26] argued for an approach where dosage was designed around the client's therapy readiness, skill level, and response to the intervention. Gannotti et al. [3] developed a clinical pathway as a method of approaching dosage (sessions per week, duration of session, and the type of specific motor/biomechanical intervention) for children with cerebral palsy (CP). The clinical pathway developed through targeting motor based interventions for children with CP is also uniquely infused with the core constructs of the International Classification System [27]. Bailes et al. [28] developed a clinical scaffold to serve as a guide for clinicians providing services which then informs them on some aspects of dosage (frequency) related to the client's response to therapy. The two clinical guides proposed by Gannotti et al. [3] and Bailes et al. [28] have yet to be explored further by way of clinician and client perspectives or intervention efficiency (greater outcomes in a shorter amount of time). Therefore, dosage is a current topic within the literature that warrants further research.

Implications for Clinical Practice.
Our findings provide an opportunity for pediatric OTs to compare their current dosage decisions but do not provide the premise for demonstrating the most effective dosage parameters to select. In    order for occupational therapy practitioners to incorporate evidence-based practice, to be adherent to the AOTA Code of Ethics (AOTA, 2010) and the 2017 American Occupational Therapy Association's Centennial Vision (Clark, 2010) [29,30], a better understanding of current dosage decisions by OTs for pediatric interventions is needed. Exploring how dosage is being implemented in clinical research may assist the occupational therapy profession to establish evidence for the prescription of services as related to frequency, intensity, and duration to ensure efficacy. Evidence-based practice should not only include information and evidence regarding valid interventions and assessments but should also include the importance of intensity, frequency, and duration when establishing plans of care for pediatric clients. With healthcare evolving, new policies, and the Affordable Care Act [31], it is going to be increasingly important for OTs to provide guidelines of treatment frequency, intensity, and duration to ensure continuation of insurance coverage for occupational therapy services, in addition to demonstrating the effectiveness and value of occupational therapy services. The findings of this study reflect the existing foundation of outcomes studies available regarding dosage and can foster reflection among occupational therapy practitioners. Such self-reflection may include guiding questions such as "what is the rationale for duration of the treatment, the number of sessions per week, and the number of minutes per session? Is what I have prescribed supported by the best possible evidence?" Occupational therapy practitioners would benefit from paying closer attention to the parameters of dosage when exploring and implementing the evidence. They should consider the specific parameters of dosage (frequency, intensity, and duration), rationale for the dosage, and the setting of the intervention delivery within each article supporting their clinical practices.

Implications for Researcher.
After reviewing 123 outcomes studies within occupational therapy specific journals there are several recommendations that researchers should consider as they disseminate findings related to occupational therapy based intervention outcomes applicable to pediatric populations or settings. Researchers should be explicit regarding the dosage parameters related to the intervention being assessed or independent variables measured. Further, it would be helpful if researchers include comments regarding the selection of dosage which may include how funding/reimbursement, time/resources, and/or setting may have been influencing factors. A clear description of how the study's methodology, dosage, and findings should or should not be interpreted and implemented in various practice settings is also needed. In addition to connecting the applicability of the findings to clinical practice, researchers should be explicit in the application of their study's methodology, dosage, and findings to better support replication.

4.9.
Limitations. The limitations of this study include a heterogeneous sample, specifically diversity among intervention types, sample sizes, conditions/populations, and the journal's focus and specific aims. In addition, the literature search revealed some extreme outliers in all categories of the intervention dosage as noted in previous sections. Lastly, we are aware that the selection of the journals reviewed may result in a content bias since there may be relevant articles published in other sources that were not included within this study.

Recommendations for Future Research.
Areas of future research should include analyzing the published research by adding categories related to setting (0-3 or early intervention, school-based, inpatient hospital and outpatient rehabilitation, and community based) and the type of research (case study or clinical). Analyzing unpublished theses and dissertations as they may include outcomes studies where the intervention did not result in significant findings and exploring their dosage may be advantageous to researchers and clinicians. Investigating outcomes studies back through 2002 may allow for the analysis to include changes in reporting of dosage and actual changes in dosage over time. Finally, evaluating pediatric outcomes studies that generated significant positive findings would be of value. In addition future research should include reviewing journals that are condition specific in an effort to establish the most effective interventions in addition to expanding the knowledge base in regard to the provision of occupational therapy services including dosage of such services. Categorizing and evaluating the funding source as a part of the outcome study (e.g., pro bono, public/private health insurance, government funded insurance, and grant funding) may also be beneficial. Including specific client factors such as severity of the physical, developmental or mental diagnosis, or occupational performance deficit would assist in the dosage discussion. Finally, the pediatric rehabilitation professions (occupational and physical therapy and speech language pathology) need to start exploring the possible links between dosage of an intervention and outcomes on an intervention by intervention and/or condition by condition basis.