Feasibility and Preliminary Efficacy of Web-Based and Mobile Interventions for Common Mental Health Problems in Working Adults: Multi-Arm Randomized Pilot Trial

Background There is growing interest in digital platforms as a means of implementing scalable, accessible, and cost-effective mental health interventions in the workplace. However, little is known about the efficacy of such interventions when delivered to employee groups. Objective This study aims to evaluate the feasibility and preliminary efficacy of a digital mental health platform for the workplace, which incorporates evidence-based practices such as cognitive behavioral therapy and acceptance and commitment therapy. A total of 3 brief, unguided interventions designed to address stress, anxiety, and resilience, respectively, are evaluated. The primary aim is to determine the feasibility of the study methods and interventions in preparation for a definitive randomized controlled trial. Methods The study used a fully remote, parallel, multi-arm, external pilot randomized controlled trial, with 3 intervention arms and a no-intervention control group. Participants were working adults representative of the general UK population with respect to age, sex, and ethnicity who were recruited from a web-based participant platform. Primary outcomes included objective and self-report measures of feasibility, acceptability, engagement, transferability, relevance, and negative effects. Secondary outcomes included 4 self-report measures of mental health and well-being, completed at baseline (time point 0 [t0]), postintervention (time point 1 [t1]), and the 1-month follow-up (time point 2 [t2]). Secondary outcomes were analyzed via linear mixed-effects models using intention-to-treat principles. Preregistered criteria for progression to a definitive trial were evaluated. Results Data were collected between January and March of 2021. A total of 383 working adult participants meeting trial eligibility were randomized, of whom 356 (93%) were retained at t2. Objective engagement data showed that 67.8% (196/289) of participants randomized to an intervention arm completed their intervention. Overall, 87.1% (203/233) of participants reported being satisfied or very satisfied with their intervention and rated the quality of their intervention as good or excellent. All intervention groups reported significantly greater improvements than the control group on at least one secondary outcome at t1, with between-group Hedges g effect sizes for the pooled interventions ranging from 0.25 (95% CI 0.05-0.46) to 0.43 (95% CI 0.23-0.64). All the improvements were maintained at t2. Conclusions The study methods were feasible, and all preregistered criteria for progression to a definitive trial were met. Several minor protocol amendments were noted. Preliminary efficacy findings suggest that the study interventions may result in improved mental health outcomes when offered to working adults. Trial Registration ISRCTN Registry 80309011; http://www.isrctn.com/ISRCTN80309011

Is this a full powered effectiveness trial or a pilot/feasibility trial? * Manuscript tracking number * If this is a JMIR submission, please provide the manuscript tracking number under "other" (The ms tracking number can be found in the submission acknowledgement email, or when you login as author in JMIR. If the paper is already published in JMIR, then the ms tracking number is the four-digit number at the end of the DOI, to be found at the bottom of each published article in JMIR) 1a) TITLE: Identification as a randomized trial in the title

1a-i) Identify the mode of delivery in the title
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.
Does your paper address subitem 1a-i? * 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 The title identifies the study as including "web-based and mobile interventions".

1a-ii) Non-web-based components or important co-interventions in title
Mention non-web-based components or important co-interventions in title, if any (e.g., "with telephone support"). Does your paper address subitem 1a-ii?
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 This study did not include any non-web-based components or co-interventions.
1a-iii) Primary condition or target group in the title Mention primary condition or target group in the title, if any (e.g., "for children with Type I Diabetes") Example: A Web-based and Mobile Intervention with Telephone Support for Children with Type I Diabetes: Randomized Controlled Trial Does your paper address subitem 1a-iii? * 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 The title refers to the interventions as addressing "common mental health problems in working adults". 1b-i) Key features/functionalities/components of the intervention and comparator in the METHODS section of the ABSTRACT Mention key features/functionalities/components of the intervention and comparator in the abstract. If possible, also mention theories and principles used for designing the site. Keep in mind the needs of systematic reviewers and indexers by including important synonyms. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-i? * 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 states that the "The study employed a fully remote, parallel, multi-arm, external pilot RCT, with three intervention arms and a no-intervention control group." The app evaluated in this study "incorporates evidence-based practices such as cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT). Three brief, unguided interventions designed to address stress, anxiety, and resilience, respectively, were evaluated."

1b-ii) Level of human involvement in the METHODS section of the ABSTRACT
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). (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-ii?
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 Your answer 1b-iii) Open vs. closed, web-based (self-assessment) vs. face-to-face assessments in the METHODS section of the ABSTRACT 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). Note: In traditional offline trials, an open trial (open-label trial) is a type of clinical trial in which both the researchers and participants know which treatment is being administered. To avoid confusion, use "blinded" or "unblinded" to indicated the level of blinding instead of "open", as "open" in web-based trials usually refers to "open access" (i.e. participants can self-enrol). (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-iii?
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 Your answer 1b-iv) RESULTS section in abstract must contain use data Report number of participants enrolled/assessed in each group, the use/uptake of the intervention (e.g., attrition/adherence metrics, use over time, number of logins etc.), in addition to primary/secondary outcomes. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it)

INTRODUCTION 2a) In INTRODUCTION: Scientific background and explanation of rationale
Does your paper address subitem 1b-iv?
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 "A total of 383 working adult participants meeting trial eligibility were randomised, of which 356 (93.0%) were retained at t2. Objective engagement data showed that 67.8% of all participants randomised to an intervention arm completed their intervention." 1b-v) CONCLUSIONS/DISCUSSION in abstract for negative trials 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. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-v?
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 Your answer Does your paper address subitem 2a-i? * 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 addressed in the background and rationale section of the Introduction. For example: "There is growing interest in online and smartphone apps as a means of increasing the reach of mental health and wellbeing interventions. Digital platforms can offer a broad range of content within a standardized environment that is interactive and dynamic, whilst also being widely accessible, cost-efficient, and non-stigmatizing." However, "there is a lack of high-quality evidence regarding the impact of MHapps when delivered to employee groups or in workplace settings, suggesting a need for further research." "To address this, we conducted an external pilot randomized controlled trial (RCT) as part of the initial testing of Unmind --a novel, digital mental health platform for the workplace. Unmind provides employees with tools to help them track, maintain, and improve their mental health and wellbeing. It features a broad range of content that draws on multiple evidence-based approaches such as cognitive behavioral therapy (CBT), mindfulness meditation (MM), behavioral activation (BA), acceptance and commitment therapy (ACT), and positive psychology. Central to the platform are individual learning and development courses (known as Series) designed to address specific topics of mental health and wellbeing. Series are short, standalone interventions, typically ranging between 5-7 sessions, each of approximately 10 minutes in duration." 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 addressed in the background and rationale section of the Introduction. For example: "Recent evidence suggests that only a fraction of for-profit mental health apps (MHapps) are supported by empirical evidence, with added concerns that such platforms are frequently characterized by low adherence. In addition, there is a lack of high-quality evidence regarding the impact of MHapps when delivered to employee groups or in workplace settings, suggesting a need for further research. To address this, we conducted an external pilot randomized controlled trial (RCT) as part of the initial testing of Unmind --a novel, digital mental health platform for the workplace. Central to the platform are individual learning and development courses (known as Series) designed to address specific topics of mental health and wellbeing." "The primary aim of this study was to evaluate the feasibility of the study methods, and three separate Unmind Series that address the topics of stress, anxiety, and resilience, respectively, in preparation for one or more future definitive RCTs. We chose to evaluate content relating to stress and anxiety as these are highly prevalent in the workplace. In addition, we chose to evaluate content relating to resilience, as evidence suggests it plays an important role in the prevention of mental health problems, and may thus be integral to the effectiveness of a preventative platform." "We chose to include more than one intervention arm in this study, as this is more efficient than performing sequential two-arm trials, and increases the proportion of participants randomized to an intervention arm. This study thus employed a parallel, multi-arm, external pilot RCT design, and recruited UK-based, community-dwelling, working adult participants, who were randomly allocated to one of three intervention arms or to a no-intervention control group. We chose to implement a no-intervention control, as 1) participants were not selected on the basis of poor mental health, or seeking help for a problem, 2) recent evidence suggests that wait-list groups may introduce nocebo effects in psychotherapy trials, and 3) participants received monetary compensation for taking part." METHODS 3a) Description of trial design (such as parallel, factorial) including allocation ratio 3b) Important changes to methods after trial commencement (such as eligibility criteria), with reasons Does your paper address CONSORT subitem 2b? * 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 "Consistent with recent guidelines on pilot trials, the primary aim of this study was to evaluate the feasibility of the study methods, and three separate Unmind Series that address the topics of stress, anxiety, and resilience, respectively, in preparation for one or more future definitive RCTs. A secondary aim was to establish the preliminary efficacy of each intervention with respect to self-report measures of stress, anxiety, symptoms of depression, and resilience, including establishing between-group effect sizes and 95% CIs (for each intervention compared to the control group)." Does your paper address CONSORT subitem 3a? * 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 study was a parallel, multi-arm, external pilot randomized controlled trial (RCT) with pre-(t0) and post-intervention (t1; two weeks after t0) assessments and a 1-month followup (t2). Participants were randomly allocated to one of three brief, self-guided psychological interventions (Series) featured on the Unmind platform, or to a no-intervention control group, with a 1:1:1:1 allocation ratio.

4a) Eligibility criteria for participants
Does your paper address CONSORT subitem 3b? * 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 There were no changes to the trial procedures or eligibility criteria during the conduct of this study.

3b-i) Bug fixes, Downtimes, Content Changes
Bug fixes, Downtimes, Content Changes: ehealth systems are often dynamic systems. A description of changes to methods therefore also includes important changes made on the intervention or comparator during the trial (e.g., major bug fixes or changes in the functionality or content) (5-iii) and other "unexpected events" that may have influenced study design such as staff changes, system failures/downtimes, etc. [2].
Does your paper address subitem 3b-i?
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

Your answer
Does your paper address CONSORT subitem 4a? * 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 "Inclusion criteria were 1) at least 18 years of age, 2) currently residing in the UK, 3) selfidentifying as being in full-or part-time employment, 4) having an active account on Prolific, 5) having access to an internet connection via a smartphone or desktop device, and 6) being fluent in English." subitem not at all important 1 2 3 4 5 essential subitem not at all important 1 2 3 4 5 essential 4a-i) Computer / Internet literacy Computer / Internet literacy is often an implicit "de facto" eligibility criterion -this should be explicitly clarified.
Does your paper address subitem 4a-i?
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 Your answer 4a-ii) Open vs. closed, web-based vs. face-to-face assessments: 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. subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 4a-ii? * 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 "Participants were working adults recruited from the Prolific online recruitment platform, and the entire study was conducted online between January and March 2021. Prolific implements a pre-screening system that allows researchers to screen for eligibility without implementing a screening questionnaire. Prolific also supports recruitment of study samples representative of the national UK population with respect to age, sex, and ethnicity. The present study drew upon this feature to maximise the generalizability of study findings." Measures taken to protect participant confidentially are detailed in the study protocol, which was preregistered on Open Science Framework (OSF) in December 2020. In brief, Prolific assigns a unique identifier (the 'Prolific ID') to each individual in their participant pool. Prolific IDs were automatically recorded alongside survey responses to allow matching of individual responses across study timepoints. Each participant randomized to an intervention arm was given a unique voucher code to redeem upon accessing the Unmind platform, which enabled the matching of objective in-app usage data to individual survey responses without accessing personal information.

4a-iii) Information giving during recruitment
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.

Does your paper address subitem 4a-iii?
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 Your answer 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 "Participants were working adults recruited from the Prolific online recruitment platform, and the entire study was conducted online between January and March 2021." Participants had to be residing in the UK at the time the study was conducted in order to take part.

4b-i) Report if outcomes were (self-)assessed through online questionnaires
Clearly report if outcomes were (self-)assessed through online questionnaires (as common in web-based trials) or otherwise.
Does your paper address subitem 4b-i? * 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 preregistered secondary outcomes were self-report measures administered online.
"The entire study was conducted online between January and March 2021. All study assessments were hosted on the Qualtrics survey platform. All participants that completed a t0 assessment were invited to complete the t1 and t2 assessments via the Prolific recruitment platform." Does your paper address subitem 4b-ii?
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 Your answer

5-i) Mention names, credential, affiliations of the developers, sponsors, and owners
Mention names, credential, affiliations of the developers, sponsors, and owners [6] (if authors/evaluators are owners or developer of the software, this needs to be declared in a "Conflict of interest" section or mentioned elsewhere in the manuscript).

Does your paper address subitem 5-i?
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 Your answer

5-ii) Describe the history/development process
Describe the history/development process of the application and previous formative evaluations (e.g., focus groups, usability testing), as these will have an impact on adoption/use rates and help with interpreting results.
Does your paper address subitem 5-ii?
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 Your answer

5-iii) Revisions and updating
Revisions and updating. Clearly mention the date and/or version number of the application/intervention (and comparator, if applicable) evaluated, or describe whether the intervention underwent major changes during the evaluation process, or whether the development and/or content was "frozen" during the trial.
Describe dynamic components such as news feeds or changing content which may have an impact on the replicability of the intervention (for unexpected events see item 3b).

Does your paper address subitem 5-iii?
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 Your answer 08/10/2021, 17:08

5-iv) Quality assurance methods
Provide information on quality assurance methods to ensure accuracy and quality of information provided [1], if applicable.
Does your paper address subitem 5-iv?
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 Your answer 5-v) Ensure replicability by publishing the source code, and/or providing screenshots/screen-capture video, and/or providing flowcharts of the algorithms used Ensure replicability by publishing the source code, and/or providing screenshots/screen-capture video, and/or providing flowcharts of the algorithms used. Replicability (i.e., other researchers should in principle be able to replicate the study) is a hallmark of scientific reporting.

Does your paper address subitem 5-v?
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 Your answer 08/10/2021, 17:08

5-vi) Digital preservation
Digital preservation: Provide the URL of the application, but as the intervention is likely to change or disappear over the course of the years; also make sure the intervention is archived (Internet Archive, webcitation.org, and/or publishing the source code or screenshots/videos alongside the article). As pages behind login screens cannot be archived, consider creating demo pages which are accessible without login.
Does your paper address subitem 5-vi?
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 Your answer

5-vii) Access
Access: Describe how participants accessed the application, in what setting/context, if they had to pay (or were paid) or not, whether they had to be a member of specific group. If known, describe how participants obtained "access to the platform and Internet" [1]. To ensure access for editors/reviewers/readers, consider to provide a "backdoor" login account or demo mode for reviewers/readers to explore the application (also important for archiving purposes, see vi). Does your paper address subitem 5-vii? * 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 "After randomization, participants assigned to one of the intervention arms were sent a message via Prolific's anonymous inbox system with instructions on how to access their intervention, including using a unique voucher code to sign-up to the Unmind platform.
[Unmind] can be accessed via web, mobile or tablet (Android or iOS), and the Unmind smartphone app can be downloaded via the Apple or Google Play stores." "Participants were offered a £7 incentive for completing each of the three study assessments, delivered via Prolific. However, participant reimbursement was not contingent upon intervention adherence." subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-viii? * 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 A detailed description of the app evaluated in this study, together with the three specific interventions evaluated, is included in the Interventions section of the manuscript. For example:

5-viii) Mode of delivery, features/functionalities/components of the intervention and comparator, and the theoretical framework
"Unmind is a digital platform designed to be used by working adults to measure, manage and improve their mental health and wellbeing. It can be accessed via web, mobile or tablet (Android or iOS), and the Unmind smartphone app can be downloaded via the Apple or Google Play stores. The platform features a wide range of resources and content created by academics and clinicians with expertise in adult mental health, and rooted in evidencebased practices such as cognitive behavioral therapy (CBT), mindfulness meditation (MM), behavioral activation (BA), acceptance and commitment therapy (ACT), and positive psychology." "The present study focused on evaluating Series. Series are brief, unguided learning and development courses, typically consisting of between 5-7 sessions, each of approximately 10 minutes in duration, that are designed to be completed sequentially, and include a mix of audio and video content, infographics, and interaction with a chatbot (see Figure 1 for example screenshots)."

5-ix) Describe use parameters
Describe use parameters (e.g., intended "doses" and optimal timing for use). Clarify what instructions or recommendations were given to the user, e.g., regarding timing, frequency, heaviness of use, if any, or was the intervention used ad libitum.
Does your paper address subitem 5-ix?
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 Your answer

5-x) Clarify the level of human involvement
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).
Does your paper address subitem 5-x?
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 Your answer

5-xi) Report any prompts/reminders used
Report any prompts/reminders used: Clarify if there were prompts (letters, emails, phone calls, SMS) to use the application, what triggered them, frequency etc. It may be necessary to distinguish between the level of prompts/reminders required for the trial, and the level of prompts/reminders for a routine application outside of a RCT setting (discuss under item 21 -generalizability). Does your paper address subitem 5-xi? * 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 "Participants randomized to one of the intervention arms received reminder messages at days 5 and 10 of the intervention (delivered via Prolific's anonymous inbox system), encouraging them to complete all intervention sessions. For the purposes of the study, participants were instructed to only engage with their allocated intervention, despite having access to the full Unmind platform, and were excluded from standard email campaigns that encourage interaction with content not evaluated in this study."

5-xii) Describe any co-interventions (incl. training/support)
Describe any co-interventions (incl. training/support): Clearly state any interventions that are provided in addition to the targeted eHealth intervention, as ehealth intervention may not be designed as stand-alone intervention. This includes training sessions and support [1]. It may be necessary to distinguish between the level of training required for the trial, and the level of training for a routine application outside of a RCT setting (discuss under item 21 -generalizability. Does your paper address subitem 5-xii? * 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 intervention arm was designed to be a standalone intervention. The study did not include any co-interventions. subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 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 All primary and secondary outcomes are detailed in the Methods section.
-Acceptability: Intervention adherence (the proportion of participants completing all 7 intervention sessions), participant satisfaction, and reasons for discontinuing the intervention.
-Engagement: Average intervention sessions completed, and three questions adapted from Sections A and B of the Mobile App Rating Scale (MARS).
-Transferability: One question adapted from Section E of the MARS.
-Relevance: One question assessing subjective relevance of the intervention.
-Negative effects: One question adapted from recent guidelines on assessing negative effects, and the proportion of participants that reliably deteriorated from t0 to t1 and t1 to t2 across all secondary outcome measures (for each intervention arm and relative to the nointervention control), as per the guidelines.
Primary outcomes were measured through a combination of objective data (captured by the Unmind platform) and self-reported data captured at t1 (and included in the Multimedia Appendix)." The preliminary efficacy of each intervention arm was assessed via self-report outcome measures delivered pre-(t0) and post-intervention (t1), and at 1-month follow-up (t2).  6a-ii) Describe whether and how "use" (including intensity of use/dosage) was defined/measured/monitored Describe whether and how "use" (including intensity of use/dosage) was defined/measured/monitored (logins, logfile analysis, etc.). Use/adoption metrics are important process outcomes that should be reported in any ehealth trial.

Does your paper address subitem 6a-ii?
Copy and paste relevant sections from manuscript text Your answer 6a-iii) Describe whether, how, and when qualitative feedback from participants was obtained Describe whether, how, and when qualitative feedback from participants was obtained (e.g., through emails, feedback forms, interviews, focus groups).

Does your paper address subitem 6a-iii?
Copy and paste relevant sections from manuscript text Your answer 6b) Any changes to trial outcomes after the trial commenced, with reasons 7a) How sample size was determined NPT: When applicable, details of whether and how the clustering by care provides or centers was addressed subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 6b? * 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 There were no changes to any trial outcomes.

7a-i) Describe whether and how expected attrition was taken into account when calculating the sample size
Describe whether and how expected attrition was taken into account when calculating the sample size.

Does your paper address subitem 7a-i?
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 The present study was powered for confidence intervals on feasibility outcomes. A sample size calculation indicated that approximately 100 participants were required to estimate feasibility outcomes with a margin of error ≤ 10% (based on a conservative population proportion of 50% for retention and/or adherence, and a 95% CI). This is consistent with previous guidelines suggesting that 60-100 participants per intervention arm is optimal for estimating binary outcomes in pilot RCTs. We therefore aimed to recruit 400 participants in total.
7b) When applicable, explanation of any interim analyses and stopping guidelines 8a) Method used to generate the random allocation sequence NPT: When applicable, how care providers were allocated to each trial group 8b) Type of randomisation; details of any restriction (such as blocking and block size) Does your paper address CONSORT subitem 7b? * 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 did not implement any interim analyses or stopping guidelines.

Does your paper address CONSORT subitem 8a? *
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 "Randomization occurred at the end of the baseline assessment, and was implemented via the Qualtrics "randomizer" feature".
Does your paper address CONSORT subitem 8b? * 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 Qualtrics implements block randomization to ensure balanced groups. 9) Mechanism used to implement the random allocation sequence (such as sequentially numbered containers), describing any steps taken to conceal the sequence until interventions were assigned 10) Who generated the random allocation sequence, who enrolled participants, and who assigned participants to interventions 11a) If done, who was blinded after assignment to interventions (for example, participants, care providers, those assessing outcomes) and how NPT: Whether or not administering co-interventions were blinded to group assignment Does your paper address CONSORT subitem 9? * 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 "Randomization was implemented via the Qualtrics "randomizer" feature, which uses block randomization to ensure balanced groups. The research team remained blind to group assignment for the duration of data collection." Does your paper address CONSORT subitem 10? * 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 Participants were automatically allocated and informed of their study arm at the end of the t0 assessment, using built-in Qualtrics features.
"The research team remained blind to group assignment for the duration of data collection. After randomization, participants assigned to one of the intervention arms were sent a message via Prolific's anonymous inbox system with instructions on how to access their intervention, including using a unique voucher code to sign-up to the Unmind platform." 11a-i) Specify who was blinded, and who wasn't Specify who was blinded, and who wasn't. Usually, in web-based trials it is not possible to blind the participants [1, 3] (this should be clearly acknowledged), but it may be possible to blind outcome assessors, those doing data analysis or those administering co-interventions (if any).
Does your paper address subitem 11a-i? * 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 "It was not possible to blind participants to group assignment. The research team remained blind to group assignment for the duration of data collection, but were unblinded during data analysis." 11a-ii) Discuss e.g., whether participants knew which intervention was the "intervention of interest" and which one was the "comparator" 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".

Does your paper address subitem 11a-ii?
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 11b) If relevant, description of the similarity of interventions (this item is usually not relevant for ehealth trials as it refers to similarity of a placebo or sham intervention to a active medication/intervention) 12a) Statistical methods used to compare groups for primary and secondary outcomes NPT: When applicable, details of whether and how the clustering by care providers or centers was addressed Does your paper address CONSORT subitem 11b? * 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 A description of the three intervention arms is included in the Methods section, which allows for a comparison of similarities and differences between them. The study utilised a nointervention control group, and thus any description of similarities between the study interventions and control group is not relevant.
Does your paper address CONSORT subitem 12a? * 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 details all statistical methods used to compare groups across both primary and secondary outcomes. For example: "Fisher's exact test of independence was used to compare categorical responses (such as post-intervention ratings) between intervention arms (with P values computed using Monte Carlo simulation and 2000 iterations). Where tests were significant, post-hoc pairwise comparisons between study arms were performed (using FDR methods to adjust P values)." Secondary outcome measures were analysed using "linear mixed effects models (LMMs) with restricted information maximum likelihood estimation (via the lme4 package in R). Each model included a within-subject factor "time" (with levels: t0, t1, and t2), a betweensubject factor "group" (CS, WW, BR, or Control), and their interaction as fixed effects, and a separate baseline for each participant." subitem not at all important 1 2 3 4 5 essential 12b) Methods for additional analyses, such as subgroup analyses and adjusted analyses 12a-i) Imputation techniques to deal with attrition / missing values 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]).
Does your paper address subitem 12a-i? * 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 "Secondary outcome measures were analysed using both intention-to-treat (ITT) and per protocol (PP) approaches. For the ITT analysis, all participants with complete t0 data were included, regardless of intervention adherence and any deviation from instructions. Participants were excluded from the PP analysis if they failed to complete all 7 intervention sessions, if they started an Unmind Series outside of their allocated intervention, or if they were lost to follow-up at t1." Analyses were performed using linear mixed effects models (LMMs), which are capable of handling missing data under the 'missing at random' assumption, and are considered superior to other missing data techniques such as single imputation.

X26) REB/IRB Approval and Ethical Considerations [recommended as subheading under "Methods"] (not a CONSORT item)
subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 12b? * 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 For each outcome in the ITT analysis, we report both unadjusted and Tukey-adjusted P values for between-group contrasts that compare change from t0 to t1, and t0 to t2, for each intervention arm (and all intervention arms combined) relative to the control group.
In addition, "Subgroup analyses were performed to examine change in secondary outcome measures for participants that self-report having at least mild symptoms at t0, or at least moderately low resilience. For simplicity, we report a comparison of Hedge's g effect sizes for these subgroups versus the ITT analysis, but omit the full output of each LMM. In addition, we analysed intervention feedback ratings for these subgroups separately."

X26-i) Comment on ethics committee approval
Does your paper address subitem X26-i?
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 Your answer 08/10/2021, 17:08

x26-ii) Outline informed consent procedures
Outline informed consent procedures e.g., if consent was obtained offline or online (how? Checkbox, etc.?), and what information was provided (see 4a-ii). See [6] for some items to be included in informed consent documents.
Does your paper address subitem X26-ii?
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 Your answer

X26-iii) Safety and security procedures
Safety and security procedures, incl. privacy considerations, and any steps taken to reduce the likelihood or detection of harm (e.g., education and training, availability of a hotline)

Does your paper address subitem X26-iii?
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 Your answer 13a) For each group, the numbers of participants who were randomly assigned, received intended treatment, and were analysed for the primary outcome NPT: The number of care providers or centers performing the intervention in each group and the number of patients treated by each care provider in each center 13b) For each group, losses and exclusions after randomisation, together with reasons Does your paper address CONSORT subitem 13a? * 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 These figures are included in a detailed CONSORT flow diagram (Figure 2). In addition, we include the following in the Results: "One participant withdrew consent post-randomization and 16 participants reported not being employed at t0 (in contrast to their prescreening responses) and were excluded from all analyses. Of the remaining 383 eligible participants, 367 (95.8%) completed an assessment at t1 and 356 (93.0%) completed an assessment at t2. A summary of intervention engagement is shown in Table 2. Of the 289 participants randomised to an intervention, 237 (82.0%) started their allocated intervention, and 196 (67.8%) completed all intervention sessions. Of those completing at least one session, 82.7% proceeded to complete all sessions, which differed across intervention arms (P=.02)." In the Methods we state: "Secondary outcome measures were analysed using both intention-to-treat (ITT) and per protocol (PP) approaches. For the ITT analysis, all participants with complete t0 data were included, regardless of intervention adherence and any deviation from instructions. Participants were excluded from the PP analysis if they failed to complete all 7 intervention sessions, if they started an Unmind Series outside of their allocated intervention, or if they were lost to follow-up at t1." Does your paper address CONSORT subitem 13b? (NOTE: Preferably, this is shown in a CONSORT flow diagram) * 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 include a detailed CONSORT flow diagram (Figure 2) that reports on losses and exclusions with reasons (where known) for each study arm. subitem not at all important 1 2 3 4 5 essential 14a) Dates defining the periods of recruitment and follow-up

13b-i) Attrition diagram
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.

Does your paper address subitem 13b-i?
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

Your answer
Does your paper address CONSORT subitem 14a? * 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 study was enrolled in January 2021 within 48 hours of launching the study advert, and data were collected between January to March 2021." "The study included pre-(t0) and post-intervention (t1; two weeks after t0) assessments and a 1-month follow-up (t2). Participants had two weeks to complete their allocated intervention, and were free to progress through the intervention at their own pace." 14a-i) Indicate if critical "secular events" fell into the study period Indicate if critical "secular events" fell into the study period, e.g., significant changes in Internet resources available or "changes in computer hardware or Internet delivery resources" Does your paper address subitem 14a-i?
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

Your answer
Does your paper address CONSORT subitem 14b? * 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 trial did not stop early.

15-i) Report demographics associated with digital divide issues
In ehealth trials it is particularly important to report demographics associated with digital divide issues, such as age, education, gender, social-economic status, computer/Internet/ehealth literacy of the participants, if known.

Does your paper address subitem 15-i? *
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 study recruited a sample representative of the UK population with respect to age, sex, and ethnicity. We report on age, education, sex, ethnicity, employment status, and workplace industry in Table 1. We did not collect data on socio-economic status or ehealth literacy, though participants were asked whether they had engaged with talking therapy or a mental health app within a 6-month period prior to taking part in the study. Participants were also required to have access to an internet connection via a smartphone or desktop device to take part in the study. 16-i) Report multiple "denominators" and provide definitions 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.
Does your paper address subitem 16-i? * 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 "Intervention sessions were characterised as "complete" if all components of the session were played, and thus engagement was defined as an integer ranging from 0-7 complete sessions per participant." Intervention engagement was based on objective in-app data provided by Unmind (the creator of the interventions evaluated in this study).
"Secondary outcome measures were analysed using both intention-to-treat (ITT) and per protocol (PP) approaches. For the ITT analysis, all participants with complete t0 data were included, regardless of intervention adherence and any deviation from instructions. Participants were excluded from the PP analysis if they failed to complete all 7 intervention sessions, if they started an Unmind Series outside of their allocated intervention, or if they were lost to follow-up at t1."

16-ii) Primary analysis should be intent-to-treat
Primary analysis should be intent-to-treat, secondary analyses could include comparing only "users", with the appropriate caveats that this is no longer a randomized sample (see 18-i). 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

Your answer
Does your paper address CONSORT subitem 17a? * 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 this is a pilot trial, intervention efficacy was evaluated as a secondary aim, and all results are considered preliminary. Between-group Hedge's g effect sizes (and 95% confidence intervals) for the four secondary outcome measures are included in Table 6, for each intervention arm (and the pooled effect of all intervention arms) relative to the control group. These include effect sizes for both intention-to-treat (ITT) and subgroup analyses.
17a-i) Presentation of process outcomes such as metrics of use and intensity of use 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).
17b) For binary outcomes, presentation of both absolute and relative effect sizes is recommended 18) Results of any other analyses performed, including subgroup analyses and adjusted analyses, distinguishing pre-specified from exploratory Does your paper address subitem 17a-i?
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

Your answer
Does your paper address CONSORT subitem 17b? * 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 None of the intervention outcomes included in this study were binary.
Does your paper address CONSORT subitem 18? * 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 Subgroup analyses were performed for all secondary outcome measures to explore intervention effects for participants self-reporting at least mild symptoms (or moderately low resilience) at t0. These are reported in the manuscript Results. Per protocol (PP) analyses are reported in the Multimedia Appendix only.
Several exploratory analyses (not pre-specified) are reported in the Results. Several minor deviations were made from the preregistered data analysis plan in order to streamline analyses, simplify the reporting of results, and provide additional statistical comparisons between the three intervention arms for relevant primary outcomes. These differences are reported in the Multimedia Appendix.

19) All important harms or unintended effects in each group
(for specific guidance see CONSORT for harms)

18-i) Subgroup analysis of comparing only users
A subgroup analysis of comparing only users is not uncommon in ehealth trials, but if done, it must be stressed that this is a self-selected sample and no longer an unbiased sample from a randomized trial (see 16-iii).
Does your paper address subitem 18-i?
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

Your answer
Does your paper address CONSORT subitem 19? * 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 There were no privacy breaches or technical problems during or after the study.
As per recent guidelines, we included one post-intervention question assessing perceived negative effects for each intervention arm. We also report on the proportion of participants that reliably deteriorated from t0 to t1 and t1 to t2 across all secondary outcome measures (for each intervention arm and relative to the no-intervention control; see Table 4). These data are reported in full in the Results.

Does your paper address subitem 19-ii?
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 Your answer 22) Interpretation consistent with results, balancing benefits and harms, and considering other relevant evidence NPT: In addition, take into account the choice of the comparator, lack of or partial blinding, and unequal expertise of care providers or centers in each group subitem not at all important 1 2 3 4 5 essential 22-i) Restate study questions and summarize the answers suggested by the data, starting with primary outcomes and process outcomes (use) Restate study questions and summarize the answers suggested by the data, starting with primary outcomes and process outcomes (use).

Does your paper address subitem 22-i? *
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 first three paragraphs of the Discussion cover the requirements of this subitem. For example: "Intervention research can be undermined by problems with intervention delivery, acceptability, participant retention, and smaller than anticipated effect sizes. Guidelines therefore suggest conducting pilot studies to test trial feasibility, and to estimate important trial parameters, prior to running a definitive trial. This study reports on the feasibility and preliminary efficacy of three interventions featured on the Unmind MHapp, when delivered to working adults in the UK. The study methods and interventions were found to be feasible, and all preregistered progression criteria were met. This suggests that a definitive trial is now warranted, though a number of minor proposed protocol amendments are discussed." "Participant retention and intervention adherence were largely consistent with or higher than comparable studies. For instance, only 7% of participants were lost to attrition at follow-up, which compares favourably to recent meta-analyses reporting average attrition rates of 23-48% for MHapp trials. Objective engagement data suggested that 68% of randomized participants (and 87% of those starting their intervention) completed all intervention sessions, which is similar to or higher than average completion rates ranging between 30-65% for other MHapp interventions." subitem not at all important Does your paper address subitem 22-ii?
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 Your answer

20-i) Typical limitations in ehealth trials
Typical limitations in ehealth trials: Participants in ehealth trials are rarely blinded. Ehealth trials often look at a multiplicity of outcomes, increasing risk for a Type I error. Discuss biases due to non-use of the intervention/usability issues, biases through informed consent procedures, unexpected events.
Does your paper address subitem 20-i? * 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 Discussion includes a section on study strengths and limitations.

21-i) Generalizability to other populations
Generalizability to other populations: In particular, discuss generalizability to a general Internet population, outside of a RCT setting, and general patient population, including applicability of the study results for other organizations Does your paper address subitem 21-i?
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 Your answer 21-ii) Discuss if there were elements in the RCT that would be different in a routine application setting Discuss if there were elements in the RCT that would be different in a routine application setting (e.g., prompts/reminders, more human involvement, training sessions or other co-interventions) and what impact the omission of these elements could have on use, adoption, or outcomes if the intervention is applied outside of a RCT setting.
Does your paper address subitem 21-ii?
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 Your answer 08/10/2021, 17:08 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 trial was preregistered at International Standard Randomized Controlled Trial Number (ISRCTN) 80309011, and a full study protocol was preregistered at Open Science Framework (OSF) in December 2020." Does your paper address CONSORT subitem 24? * Cite a Multimedia Appendix, other reference, or 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 A full study protocol was preregistered at Open Science Framework (OSF) in December 2020. This will remain under embargo until peer-reviewed publication of the manuscript.
Does your paper address CONSORT subitem 25? * 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 study was funded in full by Unmind Ltd., the creator of the interventions evaluated.

X27) Conflicts of Interest (not a CONSORT item)
subitem not at all important 1 2 3 4 5 essential About the CONSORT EHEALTH checklist yes, major changes yes, minor changes no X27-i) State the relation of the study team towards the system being evaluated In addition to the usual declaration of interests (financial or otherwise), also state the relation of the study team towards the system being evaluated, i.e., state if the authors/evaluators are distinct from or identical with the developers/sponsors of the intervention.

Does your paper address subitem X27-i?
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

Your answer
As a result of using this checklist, did you make changes in your manuscript? * What were the most important changes you made as a result of using this checklist?
Your answer