To be included, the person must be ≥18 years old, staff at an enrolled PRP, and willing to complete all training activities, deliver all components of the ACHIEVE-D curriculum, and complete data collection procedures. We will exclude staff that plans on leaving their position or taking a leave of absence from the program. Site leadership will identify potential staff to serve as coaches, and the research team will approach these individuals to discuss the study and obtain a waiver of documentation of consent. We will aim to recruit 20 coaches (at least 2 per site).

Table 2 describes the assessment schedule for the primary outcomes and implementation measures for coaches. Multimedia Appendix 3 describes other measures that we plan to collect among coaches. The following will be the primary outcome and implementation measures for coaches.

We will assess knowledge about key curricular elements using 2 measures at baseline and 6 months: a 22-item ACHIEVE-D Curriculum Weight Management Knowledge measure and a 16-item ACHIEVE-D Curriculum Exercise Knowledge measure. The research team created these questions using the best practices recommended by the National Board of Medical Examiners for item writing [18]. We will assess self-efficacy to deliver key curricular elements at baseline and 6 months using a 31-item ACHIEVE-D Curriculum Self-Efficacy measure. The research team used principles from confidence rulers in creating this measure [19], where participants rate their confidence to deliver each element on a 10-point scale. To determine fidelity, each coach will video-record their delivery of an ACHIEVE-D group session once a month. Two research team members will view each recording and use the ACHIEVE-D Curriculum Fidelity rating tool to assess performance on key elements. The research team created this tool to evaluate how a coach implements key ACHIEVE-D curriculum elements, including a counseling style consistent with MI techniques (eg, open-ended questions and affirmations) [20], within each segment (before the session, group exercise, weigh-in, focus on weight loss, role model video, commitment to high-impact behavior). Each item will be scored as absent (0) or present (2) or on a 3-point scale of absent (0), below expectations (1), or meets expectations (2). Quarterly meetings will be conducted to ensure alignment between coders. Table 3 displays example items from instruments used for the primary outcomes.

We will determine the perceived acceptability, feasibility, and appropriateness of the implementation interventions (eg, coach training) and the ACHIEVE-D curriculum. We adapted these assessments from previously validated measures [21]. We will also assess motivation and implementation climate using adapted, validated instruments [22,23]. At 6 months, we will conduct focus groups with staff coaches to elicit feedback on the following: acceptability, appropriateness, and feasibility of the implementation intervention and ACHIEVE-D curriculum; barriers to implementation; strategies to overcome barriers; and suggestions for further refinement. We will conduct a second series of focus groups or interviews at each site approximately 6 months after the conclusion of the intervention to determine whether and how the ACHIEVE-D curriculum was sustained and the challenges experienced.

Clients with SMI will participate in the ACHIEVE-D weight management program delivered by the staff coaches. To be included, the person must be ≥18 years old, a client with SMI at an enrolled PRP, BMI ≥25 kg/m² (ie, overweight or greater), and willing to make lifestyle changes to lose weight and participate in all ACHIEVE-D activities at least once a week. We will exclude individuals with contraindications to losing weight (eg, history of anorexia, liver failure, and pregnancy), who have conditions that require medically supervised weight loss (eg, myocardial infarction in the last 6 months and insulin-dependent diabetes mellitus), who plan to pursue other obesity treatments (eg, antiobesity medication and bariatric surgery), who plan to leave the PRP or move out of the geographic area within 12 months, or who are unwilling to complete all data collection procedures. Staff at each site will identify potential clients to participate who may meet the eligibility criteria; the research team will approach these individuals, on a first-come, first-served basis, to discuss the study, screen individuals, and obtain a waiver of documentation of consent. We will aim to recruit 80 clients with SMI (~8 per site).

Table 4 describes the assessment schedule for individuals with SMI. Multimedia Appendix 3 describes other measures that we plan to collect among individuals with SMI. In other studies, we have successfully used all selected measures among individuals with SMI. Similar to our prior studies, study staff will be available to assist clients with SMI complete measures, if needed. The following will be the secondary outcome and process measures for individuals with SMI.

Study staff will measure weight to the nearest 0.1 lb. on a high-quality digital scale with participants wearing light indoor clothes without shoes at baseline and 6 months. We will assess several lifestyle behaviors at baseline and 6 months. Study staff will administer the Coronary Artery Risk Development in Young Adults (CARDIA)–Early Adult Reduction of Weight through Lifestyle Intervention (EARLY) sedentary behavior questionnaire [24]. For diet, we will administer the block fat, fruit, vegetable, and fiber screener questionnaires [25,26]. We will also administer the EARLY eating away from home and sugar-sweetened beverage questionnaires [27,28]. These measures have been recommended by the National Institutes of Health Accumulating Data to Optimally Predict Obesity Treatment (ADOPT) Core Measures for Obesity Studies [29].

We will adapt prior measures to assess the helpfulness of the behavioral weight loss intervention component [30] and satisfaction with the ACHIEVE-D curriculum and staff coaches [31]. We will collect attendance and participation information for each enrolled client.

The study team’s prior research and experience with ACHIEVE informed our selection of components that will comprise the implementation interventions for the standard and enhanced arms. Both arms will use multimodal training in combination with organizational strategy meetings with site leadership to support the implementation of the ACHIEVE-D group sessions. In the enhanced arm, staff coaches will also receive performance coaching from research team members with expertise in weight management and MI.

Table 5 provides an overview of all coach training that will be conducted by the research team during the 6-month intervention period. Multimodal training will include real-time initial training via videoconference, ongoing monthly virtual training, and web-based avatar-assisted MI practice for coaches [32,33]. This training approach will provide interactive opportunities for coaches to practice the skills needed to implement the ACHIEVE-D curriculum—a more effective strategy than didactic education [34]. All coaches will receive initial training in real-time delivered via videoconferencing (approximately 14 hours in total). The initial training will include an introduction to MI, highlighting the effectiveness of this counseling style for weight management. Ongoing monthly training will be offered through a digital platform with the goal of orienting coaches to upcoming content (less than 30 minutes per month). The coaches will also have access to a web-based avatar module to review and practice MI techniques when discussing weight management with a simulated client avatar. The research team developed this module in partnership with a health care simulation company. Coaches will receive reminders to complete the monthly web-based training and avatar modules.

Programs targeting frontline staff, like ACHIEVE-D, are more effective when supplemented with implementation interventions that successfully engage organization leaders [35]. Therefore, to enhance curriculum uptake and increase engagement from site leadership [36], we will hold monthly organizational strategy meetings (30-60 minutes each month). Research team members, coaches, and site supervisors or leadership will be encouraged to attend. These meetings will support the development, adoption, and sustainment of organizational strategies needed for implementation and provide opportunities to problem-solve barriers encountered (eg, changing the class schedule to maximize attendance).

At sites randomized to the enhanced intervention arm, coaches will take part in monthly performance coaching. Performance coaching is an implementation strategy where coaches “learn by doing” and receive feedback on their ACHIEVE-D delivery [37]. Performance coaching may be particularly beneficial when evidence-based practice is new to the implementers, as is the case with ACHIEVE-D [38-40]. The performance coach will be a research team member with extensive knowledge of the ACHIEVE-D curriculum, behavioral weight loss, and MI. Each month, the performance coach and staff coach will meet to review the staff coach’s monthly video-recorded group session (see the video recording described in coach measures above). The performance coach will share their evaluation of the video, identifying areas of strength, opportunities for improvement, and a performance improvement plan (1.5 hours each month). Performance coaching feedback will be grounded in evidence-based behavioral weight loss principles and core ACHIEVE-D messages, mirror a MI style, and promote skill development and high-fidelity curriculum delivery. Of note, the study staffs who deliver performance coaching will be different from the study staff rating the video-recorded sessions for fidelity.

We will assess the effects of the implementation intervention on coaches’ knowledge, self-efficacy, and fidelity to the ACHIEVE-D curriculum, as well as client outcomes, using generalized linear mixed-effects models under the intent-to-treat approach. The mean models will include a binary intervention group indicator, time indicators, and intervention-by-time interaction terms. The time indicator coefficients estimate time-specific mean outcome changes in the standard arm, and the interaction coefficients estimate the between-arm differences of time-specific outcome changes from the baseline. The linear combination of these time-specific coefficients captures the time-specific mean outcome changes in the enhanced arm. Site differences will be assumed to follow a normally distributed random effect, while an unstructured variance-covariance matrix will be used for the repeated outcome measurements over time within individuals. For our implementation measures, we will use descriptive statistics to analyze survey measures of perceptions of acceptability, feasibility, and appropriateness of the implementation intervention and ACHIEVE-D curriculum. Point estimates and corresponding 95% confidence intervals will be obtained.

Focus groups will be audio- or video-recorded, and recordings will be transcribed. Given that we are seeking to understand experiences across sites and participants, we will use thematic analysis [41,42], which can serve as a standalone analytic method. We will use a 6-step process, which includes data familiarization, initial code generation, searching for themes (ie, repeated patterns), reviewing themes, defining or naming themes, and producing a report. The first 3 steps will be conducted by 2 research team members, and the larger research team will be involved in the final steps.