Abstract

Access to effective interventions aimed at reducing the mental health consequences of exposure to traumatic events is hampered by barriers to treatment. Mobile applications (apps) are one way to overcome these barriers. However, the effectiveness of apps in reducing posttraumatic stress symptoms (PTSS) is limited, which could be explained by low user engagement. A better understanding of the needs and preferences of individuals with PTSS could help in developing apps that are more engaging and possibly more effective. This review aims to synthesize qualitative findings from studies examining the subjective experiences of individuals who use apps for PTSS. A systematic search was conducted in Pubmed and APA PsycInfo. Empirical studies that report qualitative data and focus on one or more apps designed for the self-assessment or the self-management of PTSS were included. Sixteen articles focusing on 14 apps met the inclusion criteria. Participants reported barriers (e.g., lack of perceived benefits), facilitators (e.g., ease of use), benefits (e.g., improved mental health), and adverse effects (e.g., increased symptoms) related to the use of the apps. They also made suggestions aimed at improving user experience, such as increasing customization. In conclusion, developing apps with a user-centered approach, promoting social support through the use of the apps, and including gamification elements might increase user engagement with apps for PTSS. Further research should test if that is the case.

Keywords: posttraumatic stress disorder, intervention, mobile application, user engagement, systematic review

Disclosures: The authors have no competing interests to report.

Data Availability: Data and materials have not been made publicly available elsewhere, as all the data and materials are included in the tables, figures, and supplemental files.

Correspondence concerning this article should be addressed to Laurent Corthésy-Blondin, Faculty of Nursing, Université de Montréal, 2900 Edouard Montpetit Boulevard, Montreal, Quebec H3T 1J4, Canada. Email: laurent.corthesy-blondin@ umontreal.ca.

A potentially traumatic event (PTE) involves direct or indirect exposure to unexpected death, the fear of death, serious injury, or physical or sexual violence to self or another (American Psychiatric Association, 2022). Most people experience such an event at least once in their lives (Van Ameringen et al., 2008). Shortly after a PTE, some individuals experience posttraumatic stress symptoms (PTSS) associated with the event. PTSS are grouped into four categories, namely intrusion, avoidance, negative alterations in cognitions and mood, and reactivity (American Psychiatric Association, 2022). After a PTE, the evolution of PTSS can take different trajectories. In most cases, PTSS rapidly decrease over time. When some of the symptoms in each category last for more than 1 month after the PTE and cause clinically significant distress or functional impairments, posttraumatic stress disorder (PTSD) can be diagnosed, unless the symptoms are attributable to the physiological effects of a substance or another medical condition (American Psychiatric Association, 2022). Clinically significant PTSS can also appear gradually over the course of several months following the PTE and may eventually meet the diagnostic criteria for PTSD (Bonde et al., 2022).

PTSD and PTSS are relatively common. A study representing 26 World Health Organization member countries found that the current prevalence of PTSD was 1.4% in the general population (Koenen et al., 2017). Other studies have identified groups with a higher risk. For example, most studies of U.S. military populations report a prevalence between 5% and 15% (Schein et al., 2021), and a meta-analysis found a prevalence of 11% in ambulance personnel (Petrie et al., 2018). Moreover, up to 14.7% of individuals exposed to one or more PTE display clinically significant and persisting PTSS that do not meet the diagnostic criteria for PTSD, and higher rates have been found in studies on groups such as veterans and patients (Brancu et al., 2016). Because PTSD and PTSS are associated with significant functional impairments (Brancu et al., 2016; R. C. Kessler et al., 2005), they both represent serious public health issues.

Interventions for PTSS and PTSD

Intervention needs vary between subgroups of individuals with PTSS. The National Institute for Health and Care Excellence (NICE, 2018) offers guidelines for the best practices in the treatment of PTSS and PTSD. The NICE suggests that Individuals with persistent PTSS should be encouraged to seek help, as those who still present symptoms 30 days after a PTE are at an elevated risk of PTSD (NICE, 2018). Thus, regular assessments of PTSS in the weeks following a PTE are recommended. When PTSS are severe, especially when there are dissociative symptoms or a risk of self-harm, face-to-face cognitive behavioral therapy (CBT) is preferable compared to computer-assisted CBT and self-management apps. PTSD and PTSS sometimes present with depression, disturbances in self-identity, emotional dysregulation, and significant difficulties in interpersonal relationships. These features should be considered when planning the intervention because they can affect engagement and the success of treatment. The type of trauma can also influence treatment needs (NICE, 2018). Because of the nature of their work, military members and first responders are sometimes deeply affected by the morally challenging aspects of a traumatic event, and the guilt and shame that can follow must be addressed in treatment (Bryant, 2021).

Not all the individuals affected by PTSD or persisting PTSS seek professional treatment. The use of mental health care and services is reduced by barriers such as the lack of access, concerns related to stigma, concerns about dealing with trauma-related memories during treatment, low mental health literacy, a lack of knowledge about the services, and limited financial resources (Kantor et al., 2017). In this context, it is important to help individuals with PTSS evaluate their need for intervention and find one that corresponds to their needs. It is also important to offer them means to foster their own mental health outside of traditional services. Mobile applications (apps) for the self-assessment and self-management of PTSS may help achieve these objectives.

Mobile Applications for PTSS

The widespread adoption of mobile devices is a promising opportunity for the large-scale distribution of digital tools that can circumvent certain obstacles to care. Well-designed apps for mental health can inform individuals of the presence or absence of a mental health problem and guide those with a serious condition toward appropriate services, thus reducing obstacles related to low mental health literacy and unfamiliarity with services (Van Ameringen et al., 2017). For people who use services, mental health apps can serve as a therapeutic adjunct (e.g., Reger et al., 2015). They can also be used to help maintain the benefits of a treatment after it has ended and support individuals who are concerned with residual symptoms or relapse (Shakespeare-Finch et al., 2020). Technological advances permit the development of digital tools that replicate a multitude of evidence-based interventions. This can prove useful when the availability of mental health professionals and the financial resources are limited. For those who do not use services and those who are waiting for a treatment, self-management apps can constitute a standalone intervention (e.g., McLean et al., 2022; Riisager et al., 2021). This way of delivering services can also reduce the stigma associated with mental health (Röhr et al., 2021).

A variety of apps for the self-assessment and self-management of mental health issues have been developed and made accessible to the general population. Sander et al. (2020) conducted a systematic search of mobile apps for PTSD on the App Store and Google Play. Most components of the 69 apps identified by these authors were based on the principles of CBT. Their content included established psychological treatment methods for PTSD such as processing trauma-related emotions and beliefs, relaxation exercises, and psychoeducation (Sander et al., 2020). PTSD Coach is a popular app developed by the United States Department of Veterans Affairs to help people manage PTSS. It has four intervention components based on CBT principles: self-management of symptoms, self-assessment of symptoms, psychoeducation about PTSD, and access to support.

Despite the potential benefits of mental health apps, research does not support the effectiveness of these interventions in reducing PTSS. Randomized controlled trials have tested whether mobile apps used as standalone interventions reduced PTSS more than a passive control group (Hensler et al., 2022; Kuhn et al., 2017; McLean et al., 2022; Miner et al., 2016; Pacella-LaBarbara et al., 2020; van der Meer et al., 2020). These studies reported significant reductions in PTSS among participants in the treatment groups and in the control groups. Only one study found a significantly greater improvement in the treatment group compared with the control group (Hensler et al., 2022).

User Engagement With Apps for Mental Health, PTSD, and PTSS

Relatively few people with mental health problems adopt self-assessment and self-management apps, and those who do make little use of them (Torous et al., 2018). This also seems to apply to certain apps for PTSS, such as PTSD Coach (Owen et al., 2015), which could partly explain their limited efficacy. The health behavior technology engagement framework by Cole-Lewis et al. (2019) posits that engagement with digital tools for mental health (i.e., user interactions with a digital tool and its intervention components) promotes targeted health behaviors, which subsequently leads to the desired positive health outcomes. The benefits sought by those choosing apps for PTSS may not be limited to symptom reduction. Mental health also encompasses emotional well-being, behavioral adjustment, and a capacity to establish constructive relationships and cope with the ordinary demands and stresses of life (American Psychological Association, n.d.). If apps for PTSS do not address these needs, users may not perceive the benefits they expect or have an adverse experience with the intervention, and thus abandon the app. Empirical evidence supports the positive effect of engagement with digital mental health interventions on treatment outcomes. A meta-analysis of 25 randomized controlled trials revealed a small but significant effect of the amount of content accessed or completed and changes in the severity of the targeted mental health problems (Gan et al., 2021).

Previous reviews focused on the factors linked to engagement in studies testing digital interventions for mental health. Based on the quantitative and qualitative results from 41 studies focusing on apps for health and well-being, Szinay et al. (2020) found that factors such as the perceived utility of the app, feedback regarding the user’s performance, and well-designed reminders positively affect user engagement with those apps. In a review on the barriers and facilitators of user engagement with digital mental health interventions (e.g., web-based, smartphone-based), Borghouts et al. (2021) identified barriers such as technical issues and a lack of personalization, and facilitators such as the promotion of social connectedness by the digital intervention and improved skills (e.g., managing negative emotions). These authors also reported that the severity of mental health issues could increase interest in the intervention, but symptoms related to depression, mood, and fatigue could reduce engagement (Borghouts et al., 2021). The search strategy in these reviews did not include terms related to traumas, and few studies of apps for PTSS were analyzed. Thus, the results may not apply to such apps.

Strategies have been proposed for increasing user engagement, including gamification and user-centered design (UCD). Gamification has been defined as “the use of game design elements in non-game contexts” (Deterding et al., 2011). In a study of the use of gamification in 50 apps and other technology-based interventions for mental health, Cheng et al. (2019) identified 18 types of gamification elements. These included providing feedback on the progress in a task, attributing points or rewards when a task is completed, making users compete with each other, and allowing them to connect with each other in various ways. As its name indicates, UCD puts the users’ experiences at the center of the design. In this perspective, the continuous collaboration between mental health experts, professional designers, and end users allows to develop solutions that fit the needs and preferences of the target population. These two strategies could increase engagement with apps for PTSS. More knowledge is needed to determine which gamification elements are appropriate for apps that support people affected by a traumatic event and to identify the aspects of the users’ experiences that could be improved in future apps for PTSS.

Objective

Fostering engagement with apps for PTSD and PTSS warrants a better knowledge of the needs and preferences of trauma-exposed individuals, the challenges they face when using mobile apps, and their recommendations for improving the apps that are offered to them. Qualitative methods, such as individual interviews and focus groups, are ideal for studying these subjective experiences (Creswell & Creswell, 2017). Therefore, the objective of this research is to synthesize qualitative findings from studies examining the subjective experiences of individuals who use mobile apps for PTSS.

Method

A systematic review was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA; Moher et al., 2009). The electronic databases APA PsycInfo and Pubmed were selected because of the relevance of the periodicals they index and their limited overlap. Two syntaxes were developed (see Supplemental File 1). These syntaxes, composed of natural language terms and index terms specific to each database, reflected the themes under study: (a) mobile apps and (b) PTSD or PTSS. The search queries were performed on November 16, 2022.

Study Selection

Inclusion criteria were as follows: (a) published in English or French, (b) recruited adult participants, and (c) focused on one or more mobile apps designed for the self-assessment or the self-management of the distress or symptoms related to a traumatic event. Apps were considered to have been designed for self-management or self-assessment when they were completely self-guided or when nominal levels of support (e.g., technical) or greater levels of support (e.g., opportunity to communicate with a clinician) were offered. In contrast, apps that were used exclusively in the context of an ongoing psychotherapy were not considered eligible. Studies using apps exclusively to collect data (i.e., the app was not the focus of the study) were excluded. Another exclusion criterion was the absence of qualitative or mixed data, which was verified when assessing the full-text articles. User-testing studies (i.e., studies that evaluate the usability of an app by making potential users interact with its interface) were eligible. The following types of documents were excluded: reviews, protocols, and dissertations. All titles and abstracts were read by the first author and an undergraduate student in psychology who applied a screening grid based on the inclusion and exclusion criteria. Disagreements between the raters were resolved through consensus.

The search queries generated 849 citations in APA PsycInfo and Pubmed, of which 712 remained after eliminating the duplicates. Interrater reliability based on the screening of the titles and abstracts was 98%; k = 0.81 (Hallgren, 2012), and 38 articles were retained for full reading by the first author. At this stage, 22 articles were rejected mainly due to the absence of qualitative results. The remaining 16 articles were included in the synthesis (see Figure 1).

Data Extraction

A coding scheme was applied to the articles included for review to extract the following information: country, mobile app(s) under study, intervention duration, characteristics of the participants (population, sample size, age, gender, and PTSS severity), and methods used for the collection of the qualitative results pertaining to the participants’ subjective experiences with the app(s). The information extracted in the last category was subjected to a thematic synthesis.

Thematic Synthesis

A thematic synthesis was performed following the approach described by Thomas and Harden (2008). The thematic synthesis was initiated with an inductive, open-coding process, and the unit of analysis was the qualitative findings related to the users’ experiences with the apps reported in the “Results” section of each article. The qualitative results were read “line-by-line” and coded by the first author using Nvivo 12. Similar codes were grouped, defined, and hierarchically organized. Verbatim excerpts were not coded since they had already been analyzed by the authors of the primary studies. The resulting coding tree was then reviewed by the second author, and adjustments were made. Then, the coding scheme and excerpts (n = 120) were handed separately to the third author who assigned a code to each excerpt. The percentage of agreement between the first author and the third author was 78%. All discrepancies were resolved by consensus. At this stage, minor changes were made to the coding scheme.

Results

Study Characteristics

As shown in Table 1, the included studies were published between 2014 and 2022. They were conducted in the United States (N = 12), in European countries (N = 3), and in Australia (N = 1). Participants were mostly drawn from military populations (N = 9) or were community members exposed to a traumatic event (N = 5). Qualitative data collection methods included individual interviews (N = 10), focus groups (N = 2), and questionnaires with open-ended questions (N = 5). The age range across studies was 23–79. The percentage of males in the samples ranged from 14% to 87%. When the severity of PTSS was reported, it was measured using the PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (Weathers et al., 2013), and the mean scores ranged from 27.4 to 63.7.

Mobile Apps Under Study

Fourteen apps were identified (for a description of each app, see Supplemental File 2). PTSD Coach was the most studied mobile app (Blonigen et al., 2022; Kuhn et al., 2014; Miner et al., 2016; Shakespeare-Finch et al., 2020), including its Swedish and Australian versions (Cernvall et al., 2018; Shakespeare-Finch et al., 2020). Several other mobile apps for PTSD were examined. PTSD Help focuses on emotion regulation and psychoeducation (Riisager et al., 2021). An unnamed mobile app aims to promote resilience using principles based on acceptance and commitment therapy (Reyes, 2022; Reyes, Muthukumar, et al., 2020; Reyes, Serafica, & Sojobi, 2020). The Study to Promote Innovation in Rural Integrated Telepsychiatry (SPIRIT) app provides psychoeducation and allows patients to self-monitor, track and report symptoms to a clinician, create a safety plan for managing distress, and enter the contact numbers of supportive people (Bauer et al., 2018). Mindset, an app for the self-assessment and self-management of stress, offers emotion assessment, emotion reorientating based on CBT, a breath-timing exercise, prerecorded therapies, and a forum on which users can post positive content publicly or privately (Latour et al., 2020). One study used Mobilum, a game-based app that involves mental rotation as a visual–spatial task aimed at reducing intrusive thoughts (H. Kessler et al., 2019).

Four studies reported on mobile apps that mainly allow individuals exposed to a traumatic event to self-assess their symptoms. Because these apps were used as self-monitoring tools and not only as data collection tools, the studies were retained. Cogito Companion and T2 Mood Tracker help military personnel and veterans to self-assess their symptoms (Betthauser et al., 2020; Bush et al., 2014). The unnamed app described in Price et al.’s (2016) study was developed in order to allow patients who are hospitalized as a result of a traumatic event to monitor their symptoms and exchange information with a clinician. Another study focused on Metricwire, a technology that was originally developed for ecological momentary assessment (Price et al., 2017).

In another study (Blonigen et al., 2022), the participants were encouraged to use any of the five following Veterans Affairs apps that address common transdiagnostic mental health symptoms: PTSD Coach, Mindfulness Coach, Mood Coach, Insomnia Coach, and Anger and Irritability Management Skills (AIMS).

Main Themes From the Thematic Synthesis

Overall, five main themes were identified in the data: barriers, facilitators, perceived benefits, adverse effects, and participants’ recommendations. Each theme has one or more subthemes (see Figure 2, for a summary, and Table 2, for the definitions and illustrative excerpts).

Barriers

The first main theme refers to factors that reduced engagement with the app. As indicated in Table 2, 10 types of barriers were identified. The most frequently reported barriers were related to the lack of perceived benefits, technical issues, and design issues. A lack of perceived benefits was identified in eight studies, where participants mentioned that the app or some of its components were perceived as unhelpful or repetitive for reasons other than the design. Technical issues related to software or connectivity were reported in six studies. Most of these concerned “bugs” and challenges with wireless Internet and Bluetooth connections (e.g., Betthauser et al., 2020; Latour et al., 2020). Design issues were reported in five studies where participants thought that certain design choices made the app more challenging to use, such as the localization of certain app components (Riisager et al., 2021), the insufficient color contrast (H. Kessler et al., 2019), or a font size that was too small (Shakespeare-Finch et al., 2020).

Also noteworthy is the fact that elevated symptoms acted as a barrier in different contexts. Some participants mentioned forgetting their app when they experienced a peak in anxiety or a panic attack (Reyes, Serafica, & Sojobi, 2020; Riisager et al., 2021). PTSS such as intrusive memories also hindered regular engagement with the app (Reyes, 2022).

Facilitators

The second main theme referred to the factors that increase engagement with the app. Of the 12 subthemes, “Preferred features” was the most frequent. The features, functions, or design aspects that were appreciated included the feedback that was provided after an exercise was completed in Mobilum (H. Kessler et al., 2019) and the “calming and engaging” design of the app evaluated by Price et al. (2016). In another study conducted with veterans, some participants mentioned that they liked the veterans-centric nature of PTSD Coach (Blonigen et al., 2022). Features that promoted relaxation were also appreciated (Cernvall et al., 2018; Latour et al., 2020; Roy et al., 2015; Shakespeare-Finch et al., 2020). The second most frequent subtheme, “Ease of use,” was present in studies where participants mentioned appreciating the simple structure or design of the app, such as when it was described as “user-friendly” (Blonigen et al., 2022; Shakespeare-Finch et al., 2020).

Adverse Effects

Negative experiences were reported in two studies in which using an app exacerbated or triggered stress, distress, or PTSS. For example, some participants reported that the self-assessment component of PTSD Coach and the lack of support from a professional while using PTSD Help evoked distress (Riisager et al., 2021; Shakespeare-Finch et al., 2020).

Perceived Benefits

Seven types of positive experiences resulting from the use of the apps were reported. The most frequent was “Improved well-being and symptoms,” which was present in eight studies. It was mentioned that using the apps helped manage PTSS, sleep problems, and stress (Kuhn et al., 2014; Miner et al., 2016; Reyes, 2022; Reyes, Serafica, & Sojobi, 2020; Shakespeare-Finch et al., 2020), reach a state of relaxation, calm, or concentration (Cernvall et al., 2018; Reyes, 2022; Reyes, Serafica, & Sojobi, 2020; Riisager et al., 2021), and distract from intrusive or negative thoughts (Kanstrup et al., 2021; H. Kessler et al., 2019). Apps were perceived as beneficial for individuals who are in treatment in four studies (Bush et al., 2014; Cernvall et al., 2018; Price et al., 2016; Shakespeare-Finch et al., 2020). In three studies, using the app improved the participants’ knowledge about PTSD and their ability to explain PTSD to their family or friends (Kuhn et al., 2014; Riisager et al., 2021; Shakespeare-Finch et al., 2020). It is worth noting that the participants did not mention whether these seven types of benefits were linked to their engagement with the apps.

Participants’ Recommendations

Participants suggested ways to modify the apps in order to improve user experience. These recommendations were grouped into 11 subthemes: to provide feedback, to give the possibility to customize the app, to add notifications, to provide more information about the app, to increase social interactions, to improve the visual aspects, to add intervention components such as a crisis plan, to provide more information on PTSD and treatments for PTSD, to modify the length and the frequency of self-assessments, to promote the app, and to minimize the stigma associated with the use of the app. Regarding customization, some participants were interested in moving components within the app (Shakespeare-Finch et al., 2020), receiving assessments tailored to their specific symptoms or traumatic experience (Price et al., 2016, 2017), and changing visual aspects of the app according to their own preferences (Cernvall et al., 2018; Price et al., 2016). Some participants also mentioned that additional notifications could be useful to remind the users to engage with specific app components (Betthauser et al., 2020; Riisager et al., 2021) and with other interventions, such as medication (Price et al., 2016). Receiving a form of feedback was requested in five studies, three of which focused on apps for self-assessment (Bauer et al., 2018; Price et al., 2016, 2017). The need to increase interactions between the app users was expressed in two studies conducted with military personnel (Blonigen et al., 2022; Shakespeare-Finch et al., 2020).

Differences and Similarities Between Military and Civilian Populations

Of the 120 excerpts, 72 were retrieved from military samples and 48 from community samples. A lack of familiarity with technology, stigma, and privacy concerns were reported as barriers only by military members. Social support was perceived as a facilitator by military members, but the benefit of feeling supported was only reported by civilians. Certain barriers (e.g., lack of perceived benefits, design flaws, and technology issues), facilitators (e.g., the mobile format, preferred features, and ease of use), and adverse effects seemed to apply to both populations.

Discussion

The aim of this systematic review was to synthesize the qualitative findings from studies examining the subjective experiences of individuals who use mobile apps for PTSS. The qualitative results of the 16 included studies were divided into five main themes: barriers, facilitators, adverse effects, perceived benefits, and participants’ recommendations. Most of the barriers and facilitators were also identified in previous literature reviews on information and communication technologies related to mental health (Borghouts et al., 2021; Szinay et al., 2020). This review also highlights factors to consider in the development of apps for the self-assessment and self-management of PTSS, such as intrusive thoughts and the potential contribution of social support. It also highlights the potential utility of certain gamification elements and UCD for future apps targeting PTSS.

Distress and Posttraumatic Stress Symptoms

The severity of PTSS may act as a barrier to engagement. Some participants did not think that they would benefit from certain apps because their symptoms were not severe enough. Severe symptoms, especially intrusive thoughts, could also interfere with engagement. The review by Borghouts et al. (2021) revealed that more severe mental health symptoms were associated with a greater interest in digital interventions for mental health, but that symptoms related to depression could decrease engagement. The results of the present review add to those of Borghouts et al. (2021) by highlighting the fact that symptoms specific to PTSD may also constitute barriers to engagement. Some participants forgot about the apps when they experienced anxiety peaks or questioned the usefulness of the apps for coping with crises. This is in line with the results of a Delphi study that identified the uselessness of apps in emergency situations as one of the most relevant explanations for the low engagement with mental health apps (Torous et al., 2018).

These findings highlight the importance of considering the needs and preferences of individuals affected by a traumatic event when designing an app for this population. These apps should facilitate the deployment of strategies that users find helpful during anxiety peaks. Mobile apps could contain a crisis action plan with customizable elements. For example, users could enter the contact information of resources and people, like in the SPIRIT app (Bauer et al., 2018). How people affected by a traumatic event interact with technology should also be considered. Since some people forget the apps when experiencing an anxiety peak, developers could include components that reconnect the distressed user to their app. Natural language processing could help address this issue. Natural language processing can facilitate the detection of people in distress using textual or audio information (Shatte et al., 2019). Apps that include this type of technology could identify distressed app owners by analyzing written or voice communications made using the smartphone and send those individuals automated messages to remind them to engage with the app or have a person reach out to offer them support (Betthauser et al., 2020; Zhang et al., 2022).

Social Support and Socialization

Social support is a protective factor for PTSD that should be considered when developing apps for trauma-exposed individuals. In the present review, the interpersonal dimension of the interventions was the focus of certain subthemes. For some participants in the study by Reyes, Serafica, and Sojobi (2020), the fact that other network members were using the app was a facilitator. Regarding the benefits, some said that the intervention helped them explain PTSD to their loved ones (Kuhn et al., 2014) or reported sharing the app with another person who had been exposed to a trauma (Shakespeare-Finch et al., 2020). A subtheme among the recommendations was to increase interactions between users (Shakespeare-Finch et al., 2020). These results correspond to elements that Borghouts et al. (2021) identified as facilitators to the use of digital interventions for mental health, such as social connectedness (i.e., “the extent to which the intervention connects or isolates the user with or from others”), and social influence (i.e., “factors from the users’ social environment, such as perceptions held by their peers, family, and health care provider, that influence their intention to use an intervention”).

Peer support has been used as a strategy to foster engagement with apps for PTSS. In one study included in this review, Blonigen et al. (2022) trained veterans with mental health problems to support other veterans in their use of mental health apps. The support that was offered during four telephone sessions consisted of providing instructions and information about the apps, offering technical support, and encouraging the use of the apps (Blonigen et al., 2022). In a study that was not included in this review due to the absence of qualitative data, veterans used the Renew app which aims at treating PTSD with exposure and other intervention components (McLean et al., 2022). Participants could also invite friends or family members to download another version of the app that provided instructions on how to support the participant in treatment. In this study, the number of support persons added was positively correlated with the following indicators of engagement with the app: the total time spent in the app, the time spent on exposure activities, and the number of treatment activities completed (McLean et al., 2022). These findings, combined with those reported in the present review, show that support from loved ones and peers may facilitate the use of apps for PTSS.

Gamification

Some of the gamification elements identified by Cheng et al. (2019) reflect subthemes identified in the present review. For example, gamification elements of socialization include “social cooperation” (i.e., users working together to achieve a goal) and “social networking” (i.e., users being able to make connections with each other in various ways; Cheng et al., 2019). Social networking can take the form of a community where users have the possibility to create a public or anonymous profile and communicate with each other. As an example, the Sober Grid app allows people affected by a substance use disorder to post personal content related to remission and to meet others who are striving for sobriety (Tofighi et al., 2019). Other aspects of socialization may be less desirable in the context of mental health apps, such as those that encourage comparison and competition among users (Cheng et al., 2019; Deady et al., 2017). Such elements could reflect negatively on individuals who compare unfavorably, which could in turn reduce engagement and efficacy.

Other elements of gamification correspond to subthemes reported in this review and seem appropriate for apps targeting PTSS. These include progress feedback (i.e., providing users with indications of their progress in a task and in the overall content of the product) and the customization of certain aspects of the user experience (Cheng et al., 2019). In some of the selected studies, feedback and customization acted as facilitators to user engagement or were suggested as ways to improve the apps. Such elements could be incorporated into future apps for people with PTSS. Thus, apps for PTSS could be more attractive and engaging by providing feedback on the evolution of symptoms and skill acquisition, and by enabling users to alter color themes, to change the display of some app components (e.g., the menus), to incorporate visual or audio content they find soothing or helpful, and to create rating scales that allow them to track the issues that are the most important to them.

Adopting UCD to Increase Engagement

Important barriers to the use of apps for PTSS include the limited perceived benefits, design issues, and a lack of familiarity with technology. This indicates a gap between the intervention needs and preferences of individuals with PTSS, and the apps that are made available to them. Employing a UCD approach that puts forward the user’s point of view could lead to the development of apps that are more engaging.

The development of a digital tool using a UCD approach should follow steps that allow to identify, research, and understand the initial problem; limit and define a clear problem to be solved; develop a solution; and test, evaluate, and ready the concept for production and launch (Design Council, 2019). Early in the process, UCD can help understand the interests of specific groups. The early stages allow to identify the features of an app that are likely to be perceived as useful by prospective users (Vial et al., 2022). For example, Deady et al. (2017) surveyed firefighters, a population at risk for PTSD, about their interest in mental health apps and the features they should have. Participants considered that it was important or very important that the apps feature contents that are specific to the work context of firefighters, address both stress and wellness, and ensure confidentially. In contrast, the majority considered that the ability to compare themselves to other users was irrelevant or slightly irrelevant. Studies on the needs and preferences of specific populations are relevant because apps for PTSS do not appeal to all groups equally. For example, PTSD Coach has been evaluated with several types of users, and satisfaction with the intervention varies across populations. While nearly 90% of U.S. veterans and motor vehicle accident victims reported being at least moderately satisfied with the app (Kuhn et al., 2014; Pacella-LaBarbara et al., 2020), only 59% of Dutch health care workers indicated this level of satisfaction (van der Meer et al., 2020). In the subsequent stages of the UCD process, users participate in the creation of the prototype, then interact with it when it is produced and provide feedback (Design Council, 2019). These steps help in developing digital tools that are intuitive and easy to use, which in turn could promote engagement.

SPIRIT, an app included in the present review, was designed with a UCD approach. Bauer et al. (2017, 2018) documented the process that led to this product. In partnership with organizations involved in rural health in the United States, they organized focus groups of representative patients and care managers to identify needs, create a prototype, conduct usability testing, and adjust the app based on the participants’ recommendations. This collaboration between developers and users allowed the development of an app that meets the specific needs of the target population.

Limitations

This review has three main limitations. First, only two databases were consulted to identify bibliographic citations. Thus, relevant articles indexed in other databases may have been omitted. Second, military members were represented in most of the included studies. Their experience is not necessarily the same as that of people from the general population. Veterans have access to specific services and they are mostly men, whereas PTSD affects mostly women and civilians (American Psychiatric Association, 2022; Van Ameringen et al., 2008). However, it is worth noting that veterans and the general population endorse similar barriers and facilitators in relation to the use of traditional interventions for PTSD (Kantor et al., 2017). It is possible that this similarity between veterans and the general population also applies to digital interventions such as apps for PTSS. Third, the scope of this review is limited to apps that were developed for the self-assessment or self-management of PTSS. However, certain apps that were not developed for this purpose have been used as digital interventions for PTSS, like the popular game-based app Tetris (Kanstrup et al., 2021).

Future Directions

More than half of the potentially eligible studies were screened out when assessing the full-text articles because of a lack of qualitative data. Collecting data on the users’ subjective experiences in future research on apps for PTSS could help better understand the users’ needs and preferences in relation to this type of intervention. This, in turn, could lead to the development of apps that foster user engagement.

Gamification is a promising avenue for developing or adapting apps for PTSS. The primary motive cited for using gamification in the development of digital mental health tools is to increase engagement and effectiveness (Cheng et al., 2019). However, empirical data showing the impact of gamification elements on these outcomes are still lacking for mental health apps (Johnson et al., 2016). In this context, gamified apps should be studied to test the specific effects of gamification elements and to describe the users’ experiences. Dismantling studies (Papa & Follette, 2015) augmented with qualitative methods could generate relevant knowledge on this topic.

The experiences reported by participants in several studies highlight the need to better understand the specific challenges that people face when using digital interventions for PTSS. From a UCD perspective, it seems important to determine whether people affected by PTSS consider apps to be an appropriate solution for defusing a crisis state. If that is the case, it would be interesting to design, in collaboration with users, intervention components that are helpful in this specific context.

This synthesis shows that using apps for PTSS is associated with a variety of perceived benefits, such as a decrease in symptoms as well as improved sleep and well-being. Yet, quantitative data do not support the effectiveness of apps in reducing PTSS (Goreis et al., 2020), which may be related to low user engagement (Cole-Lewis et al., 2019). It is possible that these apps benefit certain subgroups of people more than others. Empirical studies on the effectiveness of apps for PTSS have not tested this hypothesis; instead, they only compared group means. Evaluating this type of intervention using a realistic approach seems relevant. Realistic evaluation seeks to identify the contexts and mechanisms that enable the success of an intervention. The underlying research questions are derived from the following question: “What works, for whom, in what respects, to what extent, in what contexts, and how?” (Pawson et al., 1997). Adopting this approach would make it possible to identify subgroups that benefit more from the apps and to determine the level of engagement required to obtain positive and clinically significant outcomes.

Conclusion

Individuals exposed to traumatic events reported barriers, facilitators, benefits, and adverse effects related to the use of mobile apps for PTSS. They also made suggestions aimed at improving the users’ experience with these apps. Further research is needed to determine if the adoption of a UCD approach, the inclusion of gamification elements, and the promotion of social support can increase user engagement with apps for PTSS, as well as their effectiveness.

Supplemental Materials

https://doi.org/10.1037/tmb0000121.supp

Copyright © The Author(s) 2023

Received March 27, 2023
Revision received August 2, 2023
Accepted September 1, 2023