The Aim2Be mHealth Intervention for Children With Overweight or Obesity and Their Parents: Person-Centered Analyses to Uncover Digital Phenotypes

Background Despite the growing number of mobile health (mHealth) interventions targeting childhood obesity, few studies have characterized user typologies derived from individuals’ patterns of interactions with specific app features (digital phenotypes). Objective This study aims to identify digital phenotypes among 214 parent-child dyads who used the Aim2Be mHealth app as part of a randomized controlled trial conducted between 2019 and 2020, and explores whether participants’ characteristics and health outcomes differed across phenotypes. Methods Latent class analysis was used to identify distinct parent and child phenotypes based on their use of the app’s behavioral, gamified, and social features over 3 months. Multinomial logistic regression models were used to assess whether the phenotypes differed by demographic characteristics. Covariate-adjusted mixed-effect models evaluated changes in BMI z scores (zBMI), diet, physical activity, and screen time across phenotypes. Results Among parents, 5 digital phenotypes were identified: socially engaged (35/214, 16.3%), independently engaged (18/214, 8.4%) (socially and independently engaged parents are those who used mainly the social or the behavioral features of the app, respectively), fully engaged (26/214, 12.1%), partially engaged (32/214, 15%), and unengaged (103/214, 48.1%) users. Married parents were more likely to be fully engaged than independently engaged (P=.02) or unengaged (P=.01) users. Socially engaged parents were older than fully engaged (P=.02) and unengaged (P=.01) parents. The latent class analysis revealed 4 phenotypes among children: fully engaged (32/214, 15%), partially engaged (61/214, 28.5%), dabblers (42/214, 19.6%), and unengaged (79/214, 36.9%) users. Fully engaged children were younger than dabblers (P=.04) and unengaged (P=.003) children. Dabblers lived in higher-income households than fully and partially engaged children (P=.03 and P=.047, respectively). Fully engaged children were more likely to have fully engaged (P<.001) and partially engaged (P<.001) parents than unengaged children. Compared with unengaged children, fully and partially engaged children had decreased total sugar (P=.006 and P=.004, respectively) and energy intake (P=.03 and P=.04, respectively) after 3 months of app use. Partially engaged children also had decreased sugary beverage intake compared with unengaged children (P=.03). Similarly, children with fully engaged parents had decreased zBMI, whereas children with unengaged parents had increased zBMI over time (P=.005). Finally, children with independently engaged parents had decreased caloric intake, whereas children with unengaged parents had increased caloric intake over time (P=.02). Conclusions Full parent-child engagement is critical for the success of mHealth interventions. Further research is needed to understand program design elements that can affect participants’ engagement in supporting behavior change. Trial Registration ClinicalTrials.gov NCT03651284; https://clinicaltrials.gov/ct2/show/NCT03651284 International Registered Report Identifier (IRRID) RR2-10.1186/s13063-020-4080-2

The CONSORT-EHEALTH checklist is intended for authors of randomized trials evaluating web-based and Internet-based applications/interventions, including mobile interventions, electronic games (incl multiplayer games), social media, certain telehealth applications, and other interactive and/or networked electronic applications. Some of the items (e.g. all subitems under item 5 -description of the intervention) may also be applicable for other study designs.
The goal of the CONSORT EHEALTH checklist and guideline is to be a) a guide for reporting for authors of RCTs, b) to form a basis for appraisal of an ehealth trial (in terms of validity) CONSORT-EHEALTH items/subitems are MANDATORY reporting items for studies published in the Journal of Medical Internet Research and other journals / scientific societies endorsing the checklist.
As the CONSORT-EHEALTH checklist is still considered in a formative stage, we would ask that you also RATE ON A SCALE OF 1-5 how important/useful you feel each item is FOR THE PURPOSE OF THE CHECKLIST and reporting guideline (optional).
Mandatory reporting items are marked with a red *. In the textboxes, either copy & paste the relevant sections from your manuscript into this form -please include any quotes from your manuscript in QUOTATION MARKS, or answer directly by providing additional information not in the manuscript, or elaborating on why the item was not relevant for this study. yes: all primary outcomes were significantly better in intervention group vs control partly: SOME primary outcomes were significantly better in intervention group vs control no statistically significant difference between control and intervention potentially harmful: control was significantly better than intervention in one or more outcomes inconclusive: more research is needed Otros: not submitted yet -in early draft status not submitted yet -in late draft status, just before submission submitted to a journal but not reviewed yet submitted to a journal and after receiving initial reviewer comments submitted to a journal and accepted, but not published yet  T  I  T  L  E  A  N  D  A  B  S  T  R  A  C  T   1  a  )  T  I  T  L  E  :  I  d  e  n  t  i  f  i  c  a  t  i  o  n  a  s  a  r  a  n  d  o  m  i  z  e  d  t  r  i  a  l  i  n  t  h  e  t  i  t  l  Identify the mode of delivery. Preferably use "web-based" and/or "mobile" and/or "electronic game" in the title. Avoid ambiguous terms like "online", "virtual", "interactive". Use "Internet-based" only if Intervention includes non-web-based Internet components (e.g. email), use "computer-based" or "electronic" only if offline products are used. Use "virtual" only in the context of "virtual reality" (3-D worlds). Use "online" only in the context of "online support groups". Complement or substitute product names with broader terms for the class of products (such as "mobile" or "smart phone" instead of "iphone"), especially if the application runs on different platforms. Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study The abstract does not include all key RCT elements as our paper is not a RCT. However, we included key/relevant elements for our secondary analysis. For example, the abstract identifies that this study is a secondary analysis of data from a RCT, provides information on the trial registration, and the intervention is summarized including when it was delivered, the duration of the intervention (or app use), and the three main domains (i.e., behavioral, gamified and social) that encompass most of the app features examined. Our comparator was not the randomization group but instead the engagement profile; thus, the comparisons made in our study reflect differences between app users.
Clarify the level of human involvement in the abstract, e.g., use phrases like "fully automated" vs. "therapist/nurse/care provider/physician-assisted" (mention number and expertise of providers involved, if any).  t  o  -f  a  c  e  a  s  s  e  s  s  m  e  n  t  s  i  n  t  h  e  M  E  T  H  O  D  S  s  e  c  t  i  o  n  o  f  t  h  e  A  B  S  T  R  A  C  T Mention how participants were recruited (online vs. offline), e.g., from an open access website or from a clinic or a closed online user group (closed usergroup trial), and clarify if this was a purely web-based trial, or there were face-to-face components (as part of the intervention or for assessment). Clearly say if outcomes were self-assessed through questionnaires (as common in web-based trials Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We did not provide this level of detail in the abstract, but we did provide this information in the methods section (e.g., "Participating families (n=214)  Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study In addition to the primary outcomes assessed, our abstract includes usability information for both children and parents, including patterns of engagement among Aim2Be users, a brief description of some of the patterns identified, and the relative sample size and % for each group of users (e.g., "Among parents, 5 digital phenotypes were identified: Socially engaged (n=35, 16%); Independently engaged (n=18, 9%) (parents who used the behavioral or the social features of the app, respectively), Fully engaged (n=26, 12%); Partially engaged (n=32, 15%), and Unengaged (n=103, 48%) users […] LCA revealed 4 phenotypes among children: Fully engaged (n=32, 15%); Partially engaged (n=61, 28%); Dabblers (n=42, 20%) and Unengaged (n=79, 37%) users.").
Conclusions/Discussions in abstract for negative trials: Discuss the primary outcome -if the trial is negative (primary outcome not changed), and the intervention was not used, discuss whether negative results are attributable to lack of uptake and discuss reasons. Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study The primary outcomes assessed in our paper significantly changed and were discussed in the abstract. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study As our paper is not the RCT but a new proposal to uncover intervention effects, our introduction included some of these requested elements, as well as the importance of our analytical approach. Regarding the problem and type of solution only, we discussed: 1) the problem of childhood obesity in Canada (e.g., "Childhood obesity remains a significant health problem in Canada…"); 2) limitations of current interventions (e.g. "a 2018 metaanalysis found that family-based multicomponent behavioral interventions have a small effect in reducing children's BMI in efficacy trials versus standard of care controls…"); and 3) potential benefits of mHealth interventions (e.g., "Several reviews and meta-analyses suggest that mHealth interventions offer multiple advantages to in-person interventions (e.g. real-time data collection; intervention in natural environments; lower costs; health behavior tracking with feedback; incorporation of gamified elements)…"). A detailed description of the intervention is provided in the methods section. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our introduction discusses the need and benefits of our analytical approach which is based on the identification of digital phenotypes of mHealth users, explaining why such phenotypes are important to understand intervention results (e.g. "Dose-response analyses are often measured in terms of total minutes or percentage of content examined, but this approach does not provide a nuanced picture of how users may benefit from different mHealth intervention components (i.e., what design elements of the app may be more successful in engaging participants and promoting health behavior change). Studies examining how intervention exposure impacts behavior change cannot solely focus on the quantity of the intervention received but must also consider how participants engaged with the 'active ingredients' of the intervention -namely the features that support behavior change. mHealth interventions are particularly well suited to examine in greater detail which components of the intervention participants engage with through app-analytics data.
Recently, there have been calls to develop analytical methods to process the vast amounts of data that become available using mHealth technologies and identify 'digital phenotypes' (i.e., user typologies derived from individuals' patterns of interactions with specific app features). While digital phenotypes have been used in other areas of health research (e.g., diabetes, sleep, mental health), and dietary and physical activity behaviors in a non-clinical sample, there has been little attention in the treatment of childhood obesity. Some studies have investigated which app features participants use and individual characteristics associated with partial or total use of an intervention. However, most studies evaluated usability derived from self-reported measures (e.g., asking participants about their preferences and use of app features), total app use, or use of individual features instead of focusing on patterns of app use. To our knowledge, no study targeting childhood obesity has identified users' typologies based on participants' engagement with different objectively measured components of an mHealth intervention."). Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our paper reports general information on the RCT regarding the intervention and waitlist control group, but not in detail since our analyses are not based on an RCT designmeaning that we did not compare intervention versus control group participants. A more detailed description of the design is also provided in the RCT protocol cited in our paper. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our paper provides a general description of eligibility (i.e., "Children were eligible to participate if they were aged 10-17 years and had overweight or obesity as defined by the age and sex specific World Health Organization cut-offs") and a more detailed description is available in the study protocol cited in our paper.
Computer / Internet literacy is often an implicit "de facto" eligibility criterion -this should be explicitly clarified. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study This element was not one of the eligibility criteria, only that participants would need a mobile or computer with Internet access. Open vs. closed, web-based vs. face-to-face assessments: Mention how participants were recruited (online vs. offline), e.g., from an open access website or from a clinic, and clarify if this was a purely webbased trial, or there were face-to-face components (as part of the intervention or for assessment), i.e., to what degree got the study team to know the participant. In online-only trials, clarify if participants were quasi-anonymous and whether having multiple identities was possible or whether technical or logistical measures (e.g., cookies, email confirmation, phone calls) were used to detect/prevent these.
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We specified in our methods section that the recruitment occurred both online and in-person at the clinic, and that several measurements were online and self-reported, whereas others were objectively taken through Fitbits and app-analytics ("Participating families were recruited from six weight management clinic sites across Canada as well as through Facebook. After providing consent, eligible participants completed an on-line survey, 24-hr dietary recalls and received assessment tools for height, weight and physical activity (Fitbit Flex 2) to complete baseline measurements. Participants completed follow-up assessments at the 3-and 6-month follow-ups. Families randomized to the experimental group had access to the app after completing baseline measures. Waitlisted control families were given access to the app after completing their assessment at the 3-month follow-up.
Information given during recruitment. Specify how participants were briefed for recruitment and in the informed consent procedures (e.g., publish the informed consent documentation as appendix, see also item X26), as this information may have an effect on user self-selection, user expectation and may also bias results.
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our manuscript briefly states that all participants provided online consent and cites the protocol paper which includes a detailed explanation of the consent and assent processes.
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our data were collected online and for some objectively measured information we clarified the data we used (e.g. Fitbit data were downloaded from Fitbase, and app-analytics data were provided by Ayogo, the app developers). The diet data were collected and sent to us (de-identified). All data that was sent to us were de-identified and transmitted to us via secured transfers (FTP transfer connections). Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We specified in our methods section that the data collection occurred online, and that several measurements were self-reported, whereas others were objectively taken through Fitbits and app-analytics ("After providing consent, eligible participants completed an on-line survey, 24-hr dietary recalls and received assessment tools for height, weight and physical activity (Fitbit Flex 2) to complete measurements. Parents were mailed a digital scale and a measuring tape with instructions to accurately measure their child's height and weight at home. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study The manuscript states: "Briefly, the app, co-created by Ayogo Health Inc. and the Childhood Obesity Foundation with expert input". Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study In our paper we mentioned that we examined Aim2Be version 2, briefly described the rational for design of the intervention, and cited the protocol paper which includes detailed information on previous research during the development of Aim2Be, as well as another study that examined participants' engagement with the version 1 of the app. This is mostly described in the methods subsection entitled 'The Aim2Be Intervention'. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study

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In our paper we mentioned that we examined Aim2Be version 2, and that our data were collected between March 2019 and June 2020. No major events were reported. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study

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We did not report this as it was detailed in the protocol paper which we cited. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study This is included in our paper as Figure 2. We also provided the link for the intervention. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study As we examined patterns of engagement with the app, two full sections of our paper described this content in detail: 1) the section entitled 'The Aim2Be intervention' explains the theoretical foundation of the intervention, the main components, and the versions designed for different populations (e.g. pre-teens, teens, parents), and 2) the section entitled 'Use of Aim2Be app features' which explains each of the features included in the app, the app-analytics data examined, and the participants for whom the features were made available. In addition, we included figures that show the app features and process. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We specified that participants were given access to the app over a 3-months period, and whether participants used the app or not and how they used it was one of the outcomes we examined in this paper.

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Clarify the level of human involvement (care providers or health professionals, also technical assistance) in the e-intervention or as co-intervention (detail number and expertise of professionals involved, if any, as well as "type of assistance offered, the timing and frequency of the support, how it is initiated, and the medium by which the assistance is delivered". It may be necessary to distinguish between the level of human involvement required for the trial, and the level of human involvement required for a routine application outside of a RCT setting (discuss under item 21 -generalizability Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study No involvement was necessary other than the interactions with the live coach. We specified in our paper that an app feature called "live coach" was available to some participants, meaning that they could chat with a health coach through the app. Our analysis did not focus on the live coach itself, though the number of chat sessions with the live coach was one of the 13 app features included in our Latent Class Analysis. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study

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The outcomes were pre-specified as indicated in the protocol paper even though our paper is a secondary analysis of data from the RCT. Regarding the pre-specified outcomes, our paper states: "After providing consent, eligible participants completed an on-line survey, 24hr dietary recalls and received assessment tools for height, weight and physical activity (Fitbit Flex 2) to complete measurements. Participants completed follow-up assessments at the 3-and 6-month follow-ups. Parents were mailed a digital scale and a measuring tape with instructions to accurately measure their child's height and weight at home. For all of the instruments used in this study, we provided evidence of their validity and previous use in the methods section, under the measures section. As most of our data collection instruments were created for online data collection (e.g., WEB-Q, Canadian Community Health Survey) or objectively measured digital data (e.g., step count with Fitbits, app use with app-analytics), no adaptation was required. App engagement, including participants' use of each app feature, was objectively assessed with app-analytics and described in the Measures section (e.g., "App-analytics were used to track how many times children and parents used each Aim2Be app feature […] aimsnumber of high-level goals users chose while indicating their perceived importance and potential obstacles; 2) tasks -number of activities users completed to accomplish their aims; 3) check-ins -number of times users self-monitored their progress regarding specific health behaviors with short recommendations on how to improve their behaviors; 4) articles read -number of articles providing educational content the user read, and 5) articles reflected on -number of written responses the user provided after reading an article… " etc.). Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Not applicable. We did not compare randomized groups as our study is not an RCT (we only used data collected as part of an RCT to conduct secondary analyses). Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Not applicable. We did not compare randomized groups as our study is not an RCT and all of our participants participated in the intervention. Informed consent procedures (4a-ii) can create biases and certain expectations -discuss e.g., whether participants knew which intervention was the "intervention of interest" and which one was the "comparator". Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Not applicable. We did not compare randomized groups as our study is not an RCT and all of our participants participated in the intervention, however, some of our participants did not have access to one of the app features (the live coach) and this was detailed in the measures section of our paper. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Yes, the Statistical Approach section of our paper provides a detailed description of the analyses conducted, though we did not compare intervention vs control as this was not part of our aims.
Imputation techniques to deal with attrition / missing values: Not all participants will use the intervention/comparator as intended and attrition is typically high in ehealth trials. Specify how participants who did not use the application or dropped out from the trial were treated in the statistical analysis (a complete case analysis is strongly discouraged, and simple imputation techniques such as LOCF may also be problematic [4] Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study In our study, participants who did not engaged with the intervention were still analyzed as a group of 'unengaged' users; thus, no imputation was used in this case. However, as per study design, half of the participants did not have access to one of the app features and as such they had missing data in that particular feature. As those participants were randomly selected, that missing data were missing at random and imputed as such. In our Statistical Approach section, we specified that "The LCA used Full Information Maximum Likelihood to handle data missing at random in the live coach feature (no other variable included in the LCA had missing data)". Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Yes, this is detailed in section entitled 'Ethics Approval'. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We specified that all participants provided online consent to participate in the RCT study. We conducted secondary analyses of the RCT data; thus, we did not recruit participants for our study. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Not applicable, we did not recruit participants for our stud, we conducted secondary analyses of the RCT data already collected. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We reported the number of participants allocated into each group in the RCT, however, we did not compare randomized groups. As we identified and compared latent groups considering all participants who had access to the intervention, we reported the relative sample size for each latent group analyzed. The different groups and samples are shown in figures 1 (RCT) and 5 (latent groups) from our paper.
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study All participants who participated in the RCT were analyzed in our paper, including those who did not engage with the intervention, who were also kept as part of our analytical sample.
Strongly recommended: An attrition diagram (e.g., proportion of participants still logging in or using the intervention/comparator in each group plotted over time, similar to a survival curve) or other figures or tables demonstrating usage/dose/engagement. Copy and paste relevant sections from the manuscript or cite the figure number if applicable (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study In our secondary analysis of RCT data, all participants from the RCT, including those who did not use the app ('unengaged' users), were included as part of the analytical sample. As our paper was concerned with how participants engaged with the app during 3 months and the 'dose' of the app they received, we reported all participants' use of the app during this period, including their use of each app feature. This is summarized in Figure 5.
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Each participant was recruited and started using the app in a different date, thus, we are only able to specify the overall period when the data collection occurred, which was mentioned in the 'Study design' section ("Data analyzed in this study were collected from March 2019 to June 2020"). We also reported that the follow-up measures were taken 3 and 6 months after the baseline assessment. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Yes. We mentioned that our participants were recruited through Facebook and six clinical centers across Canada, a general demographic description of the participants is provided in the results section entitled 'Demographic Characteristics of the Participants', and the characteristics for each latent group are shown in Table 2. Report multiple "denominators" and provide definitions: Report N's (and effect sizes) "across a range of study participation [and use] thresholds" [1], e.g., N exposed, N consented, N used more than x times, N used more than y weeks, N participants "used" the intervention/comparator at specific pre-defined time points of interest (in absolute and relative numbers per group). Always clearly define "use" of the intervention. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our main analyses were not by originally assigned groups as we conducted secondary analyses of an RCT where we identified latent subgroups of users based on their use of the mHealth app. We combined and analyzed data of all participants who had access to the app, and provided relative sample sizes for each assessment based on the originally assigned groups (Figure 1) as well as for each group of users based on how they used the mHealth app ( Figure 5), including those who did not use it (the 'unengaged' group). Our methods section details that 'use' is defined as the number of times participants accessed an app feature and was objectively evaluated with app-analytics. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study We conducted secondary analyses of an RCT and our sample is no longer a randomized sample. However, all of our analyses are 'intent-to-treat' as our analytical sample included all participants who had access to the app, regardless of whether they used it or not. In addition to primary/secondary (clinical) outcomes, the presentation of process outcomes such as metrics of use and intensity of use (dose, exposure) and their operational definitions is critical. This does not only refer to metrics of attrition (13-b) (often a binary variable), but also to more continuous exposure metrics such as "average session length". These must be accompanied by a technical description how a metric like a "session" is defined (e.g., timeout after idle time) [1] (report under item 6a Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Our study is not the RCT, thus, we did not provide a detailed explanation of all process outcomes. However, as our analysis was concerned with participants' engagement, we reported participants' use of the app based on their patterns of use of each app feature. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study As we conducted a secondary analysis of RCT data, all of our analyses were 'other analyses' and were based on latent subgroups identified among app users. This is clear in our paper (see Figure 1 and 'Data collection protocol' section: "Families randomized to the experimental group had access to the app after completing baseline measures. Waitlisted control families were given access to the app after completing their assessment at the 3month follow-up. This study combined data collected from baseline to 3 months in the intervention group and from 3-6 months in the waitlisted control group"). Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Not applicable as no qualitative data were collected in this study.  e  d  a  t  a  ,  s  t  a  r  t  i  n  g  w  i  t  h  p  r  i  m  a  r  y  o  u  t  c  o  m  e  s  a  n  d  p  r  o  c  e  s  s  o  u  t  c  o  m  e  s  (  u  s  e  ) Restate study questions and summarize the answers suggested by the data, starting with primary outcomes and process outcomes (use Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briefly explain why the item is not applicable/relevant for your study Yes, we recognized that "our study included a clinical sample (children with overweight or obesity), thus, our findings are limited to this population".  T  o  g  e  n  e  r  a  t  e  a  r  e  c  o  r  d  t  h  a  t  y  o  u  f  i  l  l  e  d  i  n  t  h  i  s  f  o  r  m  ,  w  e  r  e  c  o  m  m  e  n  d  t  o  g  e  n  e  r  a  t  e  a  P  D  F  o  f  t  h  i  s  p  a  g  e  (  o  n  a  M  a  c  ,  s  i  m  p  l  y  s  e  l  e  c  t  "  p  r  i  n  t  "  a  n  d  t  h  e  n  s  e  l  e  c  t  "  p  r  i  n  t  a  s  P  D  F  "  )  b  e  f  o  r  e  y  o  u  s  u  b  m  i  t  i  t  .   W  h  e  n  y  o  u  s  u  b  m  i  t  y  o  u  r  (  r  e  v  i  s  e  d  )  p  a  p  e  r  t  o  J  M  I  R  ,  p  l  e  a  s  e  u  p  l  o  a  d  t  h  e  P  D  F  a  s  s  u  p  p  l  e  m  e  n  t  a  r  y  f  i  l