Enhancing Early Engagement (E3) in Mental Health Services Training for Children's Advocacy Center's Victim Advocates: Protocol for a Randomized Clinical Trial

Background: Child maltreatment is a major public issue in the United States, yet most children affected by abuse or neglect never engage in evidence-based practices (EBP) for child mental health. Children’s Advocacy Centers (CACs’) are uniquely situated to serve as Family Navigators who connect children impacted by maltreatment to appropriate EBPs. In fact, the CAC position of Victim Advocate mirrors the Mental Health Family Navigator national initiative. Methods: We will develop, implement, and evaluate web-based and consultative training for Victim Advocates to enhance early engagement in services (E3 training). The interactive web-based training will embed key targets of knowledge and skills related to family engagement, trauma, and EBP services. Participating CACs will be randomized to E3 webinar-based training, E3 webinar plus consultation, or delayed training. The project will test the E3 training’s impact on key mechanisms of change (e.g., knowledge, skills) to improve rates of screening, referral, and access to EBP services. The feasibility of implementing the training program, and differential impact and costs by level of training will be examined. Discussion: The overarching goal of this project is to test a training that is readily implemented through CACs and examine the mechanisms for improving early engagement and, ultimately, child and adolescent mental health outcomes. Results and cost ndings will be used to plan a large-scale comprehensive, mixed-methods Hybrid Type II effectiveness-implementation and cost-effectiveness trial of Family Navigator E3 training. If outcomes are positive, considerable infrastructure exists to support the scale-up and sustainability of E3 training nationwide, by embedding the training in national CAC training protocols. Trial

while also increasing the likelihood that children referred through CACs will receive the best available treatments. Therefore, the current project will expand Victim Advocates' activities of screening and referral by supporting engagement messaging by the Multidisciplinary Team (MDT), identifying EBP in the community, and implementing strategies to overcome barriers. Developing these skills in Victim Advocates will thus help children and adolescents with maltreatment histories receive EBP to address the potential impact of their traumatic experiences. If outcomes are positive, considerable infrastructure exists to support the distribution and sustainability of E3 training, as the training can be readily accessed and embedded in CACs across the nation under the guidance of NCA training protocols.
The primary goal of this pilot study is to examine the initial feasibility, outcomes, and comparative costs of the E3 training. Speci cally, we will implement and evaluate a two-level approach to the E3 training: E3w, a professionally developed webinar-only training, compared to E3w+c, the webinar training enhanced by 10 consultation calls with experts in mental health and family engagement. Notably, webinars are cost-e cient compared to in-person training, as they primarily require initial expenditures for their creation and incur only limited additional costs for ongoing maintenance and participation. Webinars can also be made broadly available even in remote settings and require only limited disruption to direct service time when compared to time needed for travel and in-person training. Alternatively, consultation models are inherently more expensive, as they require ongoing staff to provide consultation and require consultants and consultees to devote time that could otherwise be utilized for other valued professional activities (e.g., engaging in client meetings). However, consultation allows for directed practice of skills and continued learning by consultees via guided discussions and role-plays. Previous research on EBP adoption has suggested that ongoing consultation and support improve training outcomes [39]. In addition, practice of skills is crucial for behavior change in mental health settings [40]. Finally, telemedicine technology, similar to what will be used for the consultation calls, has successfully been utilized to deliver coaching and direct feedback for mental health and associated professionals at a lower cost than in-person training while also improving outcomes over the initial training alone [41]. Given the various trade-offs between the E3w and E3w+c approaches, it is critical to compare them directly prior to selecting a candidate training strategy for potential national scale-up of E3 training.

Methods/design
Study design overview For this randomized controlled trial, we will test the feasibility, outcomes, and cost of the two levels of E3 training compared to current practices in CACs in a 1:1:1 allocation ratio. CACs will be randomized to the E3w, E3w+c, or a delayed waitlist control condition. Data will be collected directly from training participants pre-training, immediately post-training, and at follow-up. Further, utilizing NCA's standard data systems (including the Outcome Measurement System, OMS outcome data will be collected for caregivers and community stakeholders pre-and post-training. We hypothesize that the E3 training will be readily implemented within the training structure of NCA and that Victim Advocates and CAC Directors will report high levels of satisfaction with the training. More importantly, we hypothesize that E3w alone will improve Victim Advocates' knowledge, resulting in minor improvement in EBP engagement, while the addition of consultation in E3w+c will lead to increased use of engagement skills, thereby resulting in greater improvement in family engagement in EBP (see Fig. 1 for ow diagram). For purposes of the current study, we will examine family engagement via rates of mental health screening, rates of referral to EBP by Victim Advocates, and family attendance at the rst session of EBP. Cost data will be collected to support examining cost-effectiveness in future studies.

Webinar development
Training for both E3w and E3w+c is planned to be provided using the web-based platform and accessed via the Internet. Although webinars themselves are not unique to the training of professionals in mental health or child maltreatment, by using recommended practices for webinars (e.g., pre-work activities, interactive components, provision of follow-up resources [42], we plan to test an interactive and engaging training. In addition, a web-based training session is planned for CAC administrators and community stakeholders (i.e., MDT members) across both E3 and E3+w conditions. The goal of this training is to provide education regarding the role of the Victim Advocate, EBP, and strategies MDT members can use to enhance family engagement in EBP.

Consultation plan
The E3w+c training also involved two separate orientation training calls for Senior Leaders and Victim Advocates that reviewed the responsibilities and structure of the training. This was followed by 10 consultation/coaching web-based meetings, with the requirement that Victim Advocates attend 80% for successful completion. These web-based meetings are to occur over a 4 months total. The purpose of starting with weekly meetings is to solidify learning from the webinars. Calls are designed to provide opportunities to individualize learning and practice skills related to mental health screening, engagement (TIES and MI strategies) and linkage to EBP. With Victim Advocates from multiple CACs on each call, there will be shared learning, as each participant will have the opportunity to identify barriers encountered and gain feedback on the application skills. Memorandum of Understanding (MOU) or data sharing agreements with all referral sources. Selection was made at the CAC site level, rather than Victim Advocate level. This was to ensure that all Victim Advocates at the same CAC were placed in identical conditions, thereby avoiding any cross-sharing of knowledge across training conditions. See Fig. 2 for a ow-chart regarding enrollment.

Procedures
Timeline CAC administrators (Senior Leaders) and Victim Advocates from the sites that met the inclusion criteria were invited to participate and complete consenting procedures, as approved by the University of Oklahoma Health Sciences Center. Informed consent was completed with all individual participants via an electronic platform (i.e., REDCap). Participants were informed that they are allowed to discontinue participation as a site or as an individual at any time. Multiple data collection methods are planned for pretraining, post training and follow up (see Fig. 3).. After each webinar, a short training evaluation form is to be sent to E3w and E3w+c participants. Data collection will be monitored by the project coordinator, who will assist sites with any questions or concerns with assistance from the research team. Upon completion of the study, sites will receive a $600 payment for their participation.

NCA Member Statistics & Census
CACs provide administrative data to NCA on the scope of services provided and remaining service needs through two statistical sources: NCA statistics submitted every 6 months through the NCATrak case management system and NCA Member Census Surveys collected every two years through Qualtrics.
Statistics include basic outputs like number of children served, client demographics, and case resolutions.
The Census Survey includes more detailed questions on topics like funding sources, sta ng information, and information on mental health services provided by CACs and partner agencies. The most recently available Census was collected in the summer of 2018 and the next Census will be distributed in the summer of 2020.

REDCap
All project-speci c data, including measures noted below, client tracking information, and any other assessments completed by the Victim Advocates and Senior Leaders will be collected via REDCap at the University of Oklahoma Health Sciences Center [43,44]. Victim Advocates at each site will be provided with a user login for REDCap and will be able to enter in data for their site at any time. Advocates will only be able to view the data for their site.

Pre-RCT Survey
In the rst year of the project, we created and implemented an electronic survey of Victim Advocates and Senior Leaders across all CACs. The survey was collected through NCA's Qualtrics system and distributed to the national network of CACs. Survey questions focused on the current roles, responsibilities, activities, tools, and management of Victim Advocates. We received responses from 915 Victim Advocates and 540 CAC Directors. Responses on the survey were utilized by the training team to develop the E3 training. In addition, several items focusing on the mental health screening procedures and barriers that Victim Advocates face when engaging families in EBP were used in the adaptive randomization procedure (see below).

Measures
Multiple measures will be collected over the course of the study. Details regarding these measures are described in Table 1.
Proposed Mechanisms of Change.
The key mechanisms proposed for the impact of the E3 training on rates of child mental health screening, referral, and linkage to EBP are changes in Victim Advocates' knowledge and family engagement skills.
A self-report knowledge test will directly examine the knowledge Victim Advocates gain through the training process. Items developed focus on engagement strategies, trauma and effects of trauma, evidence-based mental health treatments, screening for child mental health concerns, and strategies for identifying EBP in their own communities. Our goal is to test change in knowledge acquisition by Victim Advocates. Skill (i.e., delity) measures were adapted from previous research examining self-reported delity to the TIES model [45], as well as current coding manuals for MI delity [46,47] to create a self-report checklist of skills taught in the training. In consultation with the TIES experts, we developed a self-report checklist that includes both engagement-consistent behaviors (e.g., inquiring about previous mental health experiences) as well as behaviors counter to the MI and TIES strategies (e.g., providing advice). The inclusion of both types of items will ideally decrease the demand for an overly positive response by Victim Advocates.
Factors that can affect the acquisition of knowledge and application of skills can occur at the individual and system level. As such, we included measures of Victim Advocate learning anxiety, motivation, executive functioning, attitudes, and cultural sensitivity, as well as organizational and supervisory culture and support.

Outcome Data
Targeted outcomes are as follows: implementation of screening, referrals for services, successful linkage to at least one appointment, types of services accessed (i.e., EBP status), and reduced caregiver stress. These are captured via OMS caregiver surveys and through REDCap surveys completed by the Victim Advocate to address (a) screening forms implemented, (b) engagement strategies used, (c) results of screening, (d) referrals made, and (e) rst treatment session documented by date.

Costs
To capture direct and indirect costs associated with implementing the E3 training, during the project we will track (a) the amount of time Victim Advocates spend completing the webinar and pre-work activities; (b) the number and length of consultation calls attended by each Victim Advocate (if applicable); and (c) number of screening assessments and referrals completed at each CAC. Detailed cost information will be collected at the follow-up, comprising quantitative and qualitative questions about costs associated with Victim Advocates' activities since completion of the training. Quantitative items are expected to include salary/wages and bene ts, time, and resource use, but these items may be modi ed or supplemented based on qualitative data collected during the training year. The qualitative items will focus on the impact of the family navigator model (e.g., "Describe the impact, if any, that adopting the family navigator role has had on your other job responsibilities", "What resources will be required to sustain the family navigator role at your CAC?"). Costs associated with development of the training materials and resources will be collected to direct survey of training developers during and post implementation.

Randomization
A power analysis was conducted initially to determine how many sites would be needed per randomized condition. Because we have three treatment conditions (i.e., E3w, E3w+c, delayed waitlist control), we can assess intervention effects for all three two-way combinations of interventions. The power analyses were conducted for each of these two-way comparisons. To avoid overestimating power [48], we used the smallest number of clusters in an intervention group to estimate power. Power analyses were conducted using the Optimal Design software [49]. With a small intraclass correlation (ρ=0.05) and 50 total CACs (i.e., total clusters across a pair of intervention conditions), the minimal detectable effect size (MDE) is relatively small δ=0.19 as a standardized mean difference assuming 80% power and a Type I error rate of 5%. This also assumes there are at least 200 referrals per CAC. For the same design criteria and a larger intraclass correlation (ρ=0.50) the MDE is large at 0.57. Overall, power analyses suggested that we should randomize at least 25 CACs to each condition. We received 114 applications, and the research team evaluated all applications for inclusion criteria. In addition, the research team determined if the CAC lacked capacity to participate in the training (e.g., only one part-time advocate, participation in multiple other training initiatives), they would not be included in the randomization at this time. After review, 81 sites were eligible to participate, and all were randomized. Based on factors hypothesized to in uence the outcome of interest (i.e., child engagement in EBP), the initial analysis included the followings variables: (a) type of location (urban vs. rural); (b) region of the CAC (e.g., Northeast, Southern), (c) number of children served, (g) number of total CAC staff, (d) number of advocates on staff, (e) organization type (e.g., hospital-based, government based), (f) EBP services provided onsite or via community, (h) level of MDT collaboration, (i) number of barriers CAC staff report experiencing when referring families to EBP, (j) use of a mental health screening tool, (k) advocates previous training experiences, (l) number of children reported to EBP, and (m) number of children who received EBP. The main purpose of the exploratory analysis was to specify the most predictive factors and apply them as the baseline covariates. Both variables (l) and (m) were used as outcomes, and the rest of the variables were predictors in generalized linear models. Because of the exploratory nature of this aim, as well as the existence of missing data, the major risk was a false discovery due to capitalizing on a chance occurrence.
Therefore, the analysis practiced the stepwise model selection based on multiple imputed data [50]. Notably, variables (a) region of the CAC, (b) number of barriers when referring families to EBP, and (c) use of a mental health screen tools appeared in more than 50% of the selected models from twenty imputed data. Therefore, this analysis used these three variables as the covariates in the adaptive randomization.
Covariate adaptive randomization is an approach to ensure that the participants are approximately balanced with respect to covariates in the randomization [51]. The current analysis utilized the method of permuted block randomization with eight stratas (4 region areas × 2 screen tool usage levels) to assign 81 CAC sites randomly into three arms. Group A (N = 26), Group B (N = 28) and Group C (N = 27), corresponding to E3w, E3w+c, and Delayed control respectively. A preliminary baseline equivalence test was also applied to check whether any differences between three arms existed. It did not nd any difference between groups on children's rate of referral to EBP (F (2,78)

Proposed Analyses
For the randomized controlled trial, we will conduct both quantitative and qualitative analyses that will examine the effect of the training on the key outcomes of interest. Proposed analyses are described below.

Quantitative Analytic Plan
The outcomes analysis will be obtained from the post-training and follow-up assessments of Victim Advocates and Senior Leaders, as well as the continual collection of OMS survey data from caregivers and team members. The variables collected from Victim Advocates and Senior Leaders are the time-varying and CAC-varying provider delity, knowledge, and perceptions of the utility of training. The other part of outcomes will relate to family engagement. Statistical analysis will include, but is not limited, to the following: a) applying linear mixed effect models to evaluate the changes of the primary outcomes between conditions across time, should the distribution of the outcomes and residuals suggest being appropriate [52,53]; and b) investigating the mechanism that is responsible for the causal effect between training conditions and outcomes, with the mediator of knowledge/skill achievement. Covariates collected (e.g., perceived supervisory support, learning anxiety) will also be examined for their in uence on the outcome of interest. As a feasibility study, the principal goal in this stage is to examine whether Victim Advocate knowledge and skills change due to training, what factors might be associated with the change, and how that in uences family engagement in mental health services.
Missing data will not be avoidable due to the large amount of data collected from sites across the national networks, and the repeated measurements across multiple time points. Therefore, stochastic multiple imputation methods will be used to handle missingness, if the assumption of ignorable missing mechanism can be held [54,55]. In addition, analyses will be "intent-to-treat," such that individual participants or sites who leave the study will be included in analyses.

Qualitative Analytic Strategy
The research team plans to conduct thematic analysis of all qualitative responses on evaluation and followup measures. To do so, all responses to each question will be reviewed in their entirety in order to identify broad themes within the responses. Themes will be organized into a broad codebook, and additional coding will focus on re ning themes further. Coding will be conducted by multiple members of the research team, and interrater reliability will be determined through cross-coding of responses and comparison of identi ed themes. Discrepancies will be reviewed with the larger research team to discuss and nalize coding.

Cost Analysis
We will generate descriptive statistics from the quantitative cost data to describe typical costs (i.e., means) and variability in costs (i.e., standard deviations) associated with delivery of the E3 training. Direct costs will be calculated in terms of the cost of the resource and the frequency of its use (e.g., consultation fee x number of consultation sessions). Indirect costs will be calculated by applying a shadow price [57], which estimates the value of lost productivity for alternative professional activities of CAC staff, to time spent on training activities (i.e., hourly shadow price x hours of training activities). All cost estimates will be placed on the same metric through adjustment to (a) an index year using the Consumer Price Index [58] to account for in ation and (b) national average U.S. dollar values using the Council for Community and Economic Research Cost of Living Index [59] to account for costs of living differences between CAC locations. We will sum all direct and indirect expenses separately before calculation of descriptive statistics and examine descriptive statistics for total (i.e., direct plus indirect) costs.

Discussion Innovation and anticipated contribution
Child maltreatment and co-occurring traumas (e.g., domestic violence, parental substance abuse) are core adverse childhood experiences. Mounting research has accumulated demonstrating the immediate and longstanding impact of adverse childhood experiences on physical and mental well-being [60][61][62]. Effective mitigation of this negative impact involves immediate engagement in EBPs that demonstrate restitution of well-being [63,64]. By providing linkages to services upon the outcry of child maltreatment, service navigators within CACs can facilitate both the immediate connection to needed mental health treatment as well as address "deep-rooted issues related to distrust in providers and the health system that often lead to avoidance of health problems and non-compliance with treatment recommendations" [65 p. 3543].
The success of previous trials with service navigators within health care settings [65][66][67][68] will be built upon for the current feasibility study. Uniquely, the service navigator model tested in this project occurs within the CAC, the location of child forensic interviews and other key interventions provided as part of the investigation of child maltreatment. These multidisciplinary settings are located across the country and connected through the network established by NCA. Nationwide impact on access to EBP for children who experience child maltreatment is feasible given the reach of the 900 CACs across the country [69]. Broadly, no other known existing national system of programs can add one additional component to their existing services (i.e., training Victim Advocates in mental health screening, engagement, and EBP referrals) and have such a widespread impact on the mental health outcomes of children.
The approach of directly addressing disparities in mental health care is another distinction of this trial.
Research has suggested that there are signi cant socioeconomic disparities in the experience of child maltreatment, such that children living in disadvantaged neighborhoods and poverty are disproportionately affected by abuse and neglect [70]. NCA Accreditation Standards, however, require that CACs provide services to clients regardless of their ability to pay, ensuring that all children receive necessary services. In addition, although previous work has suggested that maltreatment may occur at higher rates in minority populations, this effect is largely due to the poverty and marginalization experienced by certain racial groups [71]. As youth who are not White have been found to be less likely to engage in EBP for a variety of reasons, including experiences of discrimination and racism in the service sector [10,13,14], the development and implementation of the E3 training program may help to decrease racial and socioeconomic disparities in the delivery of EBP for children affected by maltreatment. TIES was selected to be a core of E3 training due to its success in enhancing engagement in services by families who are nancially disadvantaged and impacted by service disparities [20,28,24].
Victim Advocates within CACs are primed for becoming service navigators given their location, role, and responsibilities. Considering the vulnerabilities of and service disparities experienced by the population served by CACs, successful early engagement in mental health services will need to rise above the baseline of providing education, case management, support and assistance in accessing services. This trial tests the feasibility of integrating well-de ned models (i.e., MI and TIES) designed to directly acknowledge and address distrust of service systems and integrate strategies found to reduce internal barriers to change behavior.
Large-scale implementation within complex service systems can be fraught with challenges. Expert recommendation is to construct small changes utilizing the current structure rather than attempt to overhaul the entire system [72]. This logic is readily applied to the current project, as the Victim Advocate position is already embedded and integral to the work of CACs. The E3 training is designed to enhance their capacity, testing whether enhanced skills of the Victim Advocate and the success of early engagement in EBP can be readily accomplished with web-based training alone (E3w) or signi cantly augmented through consultation (E3w+c). The results of this feasibility study will inform a larger randomized trial, integrating longitudinal design to examine the impact of Victim Advocate training on the child and family outcomes, as well as potential cost/bene t implications. If successful, the E3 project can inform the development of family navigator models for other settings (e.g., schools) [73] and clinical problems (e.g., problematic sexual behavior, for which service responses are even more challenging to coordinate than for maltreatment) [74].

Limitations/practical & operational challenges
Although the current project offers many strengths, limitations and potential challenges warrant comment. Initial plans for data collection were to utilize NCATrak, NCA's proprietary tracking software used by CACs to record data on their clients served, anticipating that most sites would be using the software. However, upon investigation of the potential CAC sites' procedures, the variety of database programs used, and the number of changes required for each system, this was determined to be impractical for collection and integration of data across CACs for the current project. As such, we shifted data collection to one central system, REDCap.
However, the decision to use REDCap has not been without challenges, as we have had to train Victim Advocates on the system's procedures and activities. Creating training videos on REDCap procedures and holding open "o ce hours" with the research team for troubleshooting concerns have facilitated the process.
Further, to examine delity to the model, Victim Advocate implementation of engagement strategies like MI and TIES had to be collected via self-report methods, due to the signi cant impact on the budget of observational methodologies. Notably, research has suggested that professionals are able to reliably selfreport on their use of intervention techniques with a high level of concordance with observer and expert ratings of the same variables [75,76]. Observational methodologies are planned to verify changes in skills in the next step of the research.
An unanticipated challenge of the current project has been the rate of job turnover of CAC personnel. In response, we are adding measures related to turnover intent, job satisfaction, and burnout to the post and follow up data collection waves to better understand this phenomenon within the CAC. Our experience highlights the importance of using a readily accessible, effective training platform and the need to examine the impact of training on job retention. Previous research has demonstrated that training in EBP with associated consultation signi cantly improved job retention of bachelor's level home-based parenting service providers working with vulnerable families (i.e., half the job turnover rate than the other conditions) [77].
Currently, we are implementing an intent-to-train analytic plan by asking those sites who left the training to complete data collection at post-training and follow-up. Lessons learned from this feasibility trial will inform a large randomized trial in the future.
Another unanticipated di culty has been COVID-19. The pandemic and related stay-at-home orders has had direct and profound impact on the CAC activities as well as the well-being of the staff and the families they serve. Transitioning CAC services to tele-health platforms was essential. Throughout the crisis, we have endeavored to provide support to Victim Advocates in their understanding and skill in administering the screener and using TIES and MI strategies via the phone and telehealth platforms. By providing video training and additional consultation, we hope to broaden the CACs' use of the training. In addition, exibility and changes in the timeline allowed CACs space to adjust to the changes caused by COVID-19 and improve learning. Finally, measures of COVID-19 impact on well-being and CAC functioning will be integrated in post and follow up data collection waves, which will provide opportunities to examine the process of family engagement during considerable stress and strain.

Future Directions
CACs are uniquely well situated to connect families to EBPs in order to target the range of mental health symptoms and disorders of children impacted by maltreatment and other traumatic experiences. The overarching goal of this project is to test the feasibility of a Family Navigator training for Victim Advocates at CACs across the nation and to examine the mechanism that improves children's early engagement in EBP.
Ultimately, our goal is to improve child and adolescent mental health outcomes. Quantitative results will allow us to establish the e cacy of the training overall, while qualitative feedback provided by Victim Advocates, CAC directors, and MDT partners will allow us to determine what improvements and changes are needed to the E3 training to allow for wider implementation in the future. Finally, results of the cost analysis will provide critical information about the resources required for E3 training and inform our approach to comparing economic costs and outcomes between different training models. If outcomes are positive, considerable infrastructure exists to support the scale-up and sustainability of E3 training, by embedding the training in all CACs under the guidance of NCA training protocols. Using the results of the current study, we plan to proceed to a larger-scale mixed-methods clinical effectiveness-implementation (Hybrid Type II [78]) and cost-effectiveness trial of the E3 training on child mental health outcomes. These various efforts will support examining broader implementation of the E3 Family Navigator model through CACs nationwide, offering tremendous potential to reduce the social and economic impact of child maltreatment by linking some of our most vulnerable children and families to high-quality mental health treatment.

Declarations
Ethics approval and consent to participate: Ethics approval was obtained from the Institutional Review Board at the University of Oklahoma Health Sciences Center (Protocol #11290).

Consent for publication: Not applicable
Availability of data and materials: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Authors' contributions. ET led the design and execution of this trial under the mentorship of JS, and wrote the rst draft of this manuscript. AD assisted with the trial and with writing the rst draft of this manuscript, and leads the cost analysis. MM, YT, KL, and AJ assisted with the trial, and reviewed and provided feedback on this manuscript. MM and KL lead the involvement of National Children's Alliance for recruitment and data collection. YT leads data management and analysis. AJ coordinates data collection. JS oversees the design and execution of all aspects of this trial as PI, and oversaw the writing of this manuscript.  Figure 1 Flow chart of study premise and hypotheses.

Figure 1
Flow chart of study premise and hypotheses.

Figure 2
Flow diagram of site enrollment and randomization.

Figure 2
Flow diagram of site enrollment and randomization.

Figure 3
Page 31/31 Data collection time points.

Figure 3
Data collection time points.

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