Development and Use of Mobile Messaging for Individuals With Musculoskeletal Pain Conditions: Scoping Review

Background Population studies show that musculoskeletal conditions are a leading contributor to the total burden of healthy life lost, second only to cancer and with a similar burden to cardiovascular disease. Prioritizing the delivery of effective treatments is necessary, and with the ubiquity of consumer smart devices, the use of digital health interventions is increasing. Messaging is popular and easy to use and has been studied for a range of health-related uses, including health promotion, encouragement of behavior change, and monitoring of disease progression. It may have a useful role to play in the management and self-management of musculoskeletal conditions. Objective Previous reviews on the use of messaging for people with musculoskeletal conditions have focused on synthesizing evidence of effectiveness from randomized controlled trials. In this review, our objective was to map the musculoskeletal messaging literature more broadly to identify information that may inform the design of future messaging interventions and summarize the current evidence of efficacy, effectiveness, and economics. Methods Following a prepublished protocol developed using the Joanna Briggs Institute Manual for Evidence Synthesis, we conducted a comprehensive scoping review of the literature (2010-2022; sources: PubMed, CINAHL, Embase, and PsycINFO) related to SMS text messaging and app-based messaging for people with musculoskeletal conditions. We described our findings using tables, plots, and a narrative summary. Results We identified a total of 8328 papers for screening, of which 50 (0.6%) were included in this review (3/50, 6% previous reviews and 47/50, 94% papers describing 40 primary studies). Rheumatic diseases accounted for the largest proportion of the included primary studies (19/40, 48%), followed by studies on multiple musculoskeletal conditions or pain sites (10/40, 25%), back pain (9/40, 23%), neck pain (1/40, 3%), and “other” (1/40, 3%). Most studies (33/40, 83%) described interventions intended to promote positive behavior change, typically by encouraging increased physical activity and exercise. The studies evaluated a range of outcomes, including pain, function, quality of life, and medication adherence. Overall, the results either favored messaging interventions or had equivocal outcomes. While the theoretical underpinnings of the interventions were generally well described, only 4% (2/47) of the papers provided comprehensive descriptions of the messaging intervention design and development process. We found no relevant economic evaluations. Conclusions Messaging has been used for the care and self-management of a range of musculoskeletal conditions with generally favorable outcomes reported. However, with few exceptions, design considerations are poorly described in the literature. Further work is needed to understand and disseminate information about messaging content and message delivery characteristics, such as timing and frequency specifically for people with musculoskeletal conditions. Similarly, further work is needed to understand the economic effects of messaging and practical considerations related to implementation and sustainability. International Registered Report Identifier (IRRID) RR2-10.1136/bmjopen-2021-048964


Background
Musculoskeletal conditions, those affecting the bones, muscles, and joints, are recognized as a global public health problem, although the prevalence and burden of healthy life lost are difficult to estimate with certainty because population studies are few [1].Where representative studies have been conducted, they have consistently shown high prevalence of musculoskeletal conditions that increases with age and has a greater burden on female than male individuals [2][3][4][5].In the Health Survey for England 2018, a total of 17% of adults reported having a long-term musculoskeletal condition (19.5% female vs 14.2% male), with prevalence increasing with age (4.7% at the ages of 16-24 years vs 39% at the age of ≥85 years).A total of 80% of people who reported having a long-term musculoskeletal condition also reported chronic pain (pain for >3 months), with 34.8% reporting pain that highly interfered with their life activities [4,5].The Australian National Health Survey 2017 to 2018 reported that 29% of Australians were living with a chronic musculoskeletal condition (age standardized; adults aged ≥45 years: 51%; 55.3% female vs 47.3% male) [3].musculoskeletal conditions were the second leading contributor to total burden of healthy life lost, equal to the burden of cardiovascular disease (13% of total burden in disability-adjusted life years), second only to cancer (18% of total burden) [2].Prioritizing the delivery of effective treatments is necessary to address the substantial burden of musculoskeletal conditions.
With the ubiquity of consumer devices such as smartphones and tablets, technology may have a useful role to play in the management and self-management of musculoskeletal conditions; potentially improve accessibility of health care; and, in some circumstances, ease health system pressures.The use of technology for providing health-related activities is typically described as "digital health" and, more specifically, "mobile health" (mHealth) when referring to the use of mobile devices.While still a relatively new field, mHealth already has a considerable literature base, with examples of its use across most health disciplines and across the continuum of care from health promotion and prevention [6,7] to screening and diagnosis [8,9], therapy [10,11], and self-management [12,13] to cancer survivorship and palliative care [14,15].While mHealth shows promise in improving aspects of health care, evidence to date is mixed, and caution is needed in interpreting the clinical value of mHealth for patients [16].
In this review, we focused on the development and use of mHealth for individuals with musculoskeletal pain conditions and specifically on health-related interactions that use text messaging as the delivery mechanism (SMS text messaging or messages provided via app-based push notifications), either alone or alongside another intervention.As one of the mobile technologies that have been established for longer, text messaging is familiar, easy to use, convenient, low cost, and available to anyone with a mobile device [17].Messaging can be used as a vehicle to promote behavior change and guide self-management through prompts, reinforcement, reminders, activity recording, feedback, and adaptivity to the individual [17,18].The effectiveness of messaging interventions has been assessed for a wide range of health problems, such as medication adherence and lifestyle change in diabetes; encouraging abstinence in smoking cessation; and, more recently, to encourage prevention behaviors during the COVID-19 pandemic [17,[19][20][21].

Data Sources
We searched PubMed, CINAHL (via EBSCOhost), Embase, and PsycINFO (via APA PsycNET) using a strategy that combined controlled-vocabulary and free-text search terms related to messaging and musculoskeletal concepts.Because of resource limitations, we were unable to include gray literature in our searches.

Search Strategy
The search strategy is described in detail in the published protocol [40], and the search queries are provided again in this paper in Multimedia Appendix 1.The search strategy was developed through discussion among the team and an iterative process of pilot searches.The final searches were conducted by SSR.Because of resource limitations, we restricted our searches to articles published in English, and because the area of digital health is a rapidly changing field, we limited our searches to articles published in the previous 10 years.

Study Selection
We exported search results to EndNote (version X9; Clarivate Analytics) and Covidence (Veritas Health Innovation) [43] for duplicate removal and to manage the screening, selection, and record-keeping processes.We conducted study selection in 3 phases.First, using the predefined inclusion and exclusion criteria, 2 independent reviewers (from a pool of 7; SSR, JL, CEE, RE, CR, SR, and NA) screened the titles and abstracts to identify candidate articles for inclusion and to discard irrelevant articles.Second, 2 reviewers from the same pool reviewed the full text of each candidate article.Third, we searched the reference lists of the included papers to identify any further articles.At all stages, conflicts were resolved using a third reviewer from our pool.

Data Extraction
Data were extracted by one reviewer (JL) and independently confirmed by 2 others (NA and CEE).Data were extracted using predefined extraction forms, as described in the protocol [40].

Synthesis and Reporting
We described the results of the study selection process using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram [44], with findings reported in accordance with the PRISMA-ScR checklist [42].For each of our 5 review questions, we structured our findings using tables adapted from the Joanna Briggs Institute manual [41] refined as necessary at synthesis stage [40].We then developed a narrative summary of the evidence for each of our review questions.

Protocol Deviations
There were 4 minor protocol deviations.First, we excluded studies that described the use of mobile messaging to collect data in cases in which those data were not subsequently used to inform care or self-management (eg, studies that simply tested the feasibility of using text messaging to collect data and studies that used text messaging as a data collection method to model recovery trajectories).Second, we included study protocols associated with evaluation studies if they provided useful information about messaging design and development.Third, we classified the level of development of the country in which the study was conducted using the Human Development Index (HDI) [45].Finally, we reran our searches in 2022 and, therefore, included studies from a 12-year period rather than the originally specified 10 years.

Overview
Literature searches were conducted in August 2020 and repeated in May 2022.In this section, we present the combined results of both searches.We identified a total of 8328 papers (published in 2010-2022) for screening, of which 50 (0.6%) were included in this review.A PRISMA flowchart of the article selection process is shown in Figure 1.

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We identified 3 previous systematic reviews, 2 (67%) of which we had already found while developing the protocol for this review [22,23] and 1 (33%) that was new [46].One review focused specifically on the effects of text messaging for managing musculoskeletal pain conditions [22], while the remainder focused more broadly on digital health or mHealth for musculoskeletal conditions but covering some aspects of messaging [23,46].The previous reviews were conducted in Australia, the United Kingdom, and the Netherlands, all countries classed as very highly developed according to their HDI.The characteristics of the reviews are shown in Table 1, and the findings are shown in Table 2.We did not identify any previous reviews related to design aspects of messaging for musculoskeletal pain conditions.
Pain or function assessed via RCTs.Not described Aspects of messaging were described in each of the following: 3 studies on self-management of back pain [24,25,27], 1 digitally delivered multidisciplinary pain program for back pain [28], and 1 conservative digital care program for knee pain [26].

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Messaging (along with phone calls or email reminders) was described in the context of "additional efforts to encourage engagement" or "additional forms of support."

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Review concluded that "additional forms of support" may be linked to positive outcomes (including improvement in pain and function); however, variability in messaging intervention characteristics hinders conclusions regarding effectiveness specific to messaging.
Seppen et al [46], 2020-asynchronous mHealth i interventions for RA Messaging not evaluated directly; rather, patient outcomes relevant to the primary objective were assessed, such as medication compliance [32] and sedentary time [37,48].
Not described Included 3 RCTs assessing the effectiveness of SMS text message reminders for medication adherence [32] and reducing sitting time [37,48].
• Findings included the following: Chen et al [30], 2017 a On the basis of the lead author's affiliation.

Previous Reviews
In the previous reviews [22,23,46] (Tables 1 and 2), the most commonly reported messaging interventions were for people with rheumatoid arthritis (RA) and back pain.For RA, messaging was used to monitor medication and disease activity [31] and improve medication adherence [32,46] and for reminders to reduce daily sitting time [37,46].For people with back pain, messaging was used mostly as a component of self-management, with approaches focused on education and behavior change strategies [24,25], supportive messages provided by a health coach during periods of low engagement with a digital self-management program [27], and motivating messages sent as part of a multidisciplinary pain program [28].
Other studies described uses of messaging for people with knee pain, systemic lupus erythematosus, frozen shoulder, chronic widespread pain, and limb injuries or conditions.For knee pain, one study reported a lifestyle intervention focused on behavior change [22,38], and another reported participation reminders and app-based messaging with a personal coach as part of an exercise, education, or cognitive behavioral therapy (CBT) or weight loss or psychosocial support program [23,26].For frozen shoulder, reminder, encouragement, and education messages were used to promote exercise compliance and improve shoulder function [30].For chronic widespread pain, a CBT intervention used SMS text message diary completion prompts, with those diary entries then informing the treatment used by a therapist [35].For limb injuries and conditions, messaging was used to promote adherence to a home exercise program in one study [36].

Osteoarthritis Studies
Of the 8 studies on osteoarthritis, 2 (25%) focused on behavior change based on personalized goals.In the first study, which proposed personalized goals based on machine learning, participants were sent daily push notifications to remind them of their goals together with an interesting fact or answer to a frequently asked question [59,80].Similarly, the second study used messaging to provide reminders to complete individualized physician-assigned goals and tasks, for which participants also used messaging to provide confirmation, or otherwise, that they had completed their personalized goals [55].
A total of 4 (50%) of studies focused on physical activity and exercise behavior change for people with knee osteoarthritis: of those, 1 (25%) used messages to decrease inactive behavior in people with knee osteoarthritis [53] and another (25%) used targeted personalized motivational reinforcement messages based on previous and current physical activity for people with osteoarthritis and sleep disturbance [57].In the third study, which had an experimental design, the authors also explored patient attitudes and experiences of a self-directed digital health intervention incorporating automated messages to support strengthening exercises [78,79].The fourth study, in which 77% of participants had knee osteoarthritis, described a digital care program that sent participants reminder messages if they did not engage with the program at the required intensity and also allowed participants to communicate with their health coach using messaging [26].
A single study focused on providing information for people with knee osteoarthritis, where messages were used to improve patients' knowledge about their condition and treatment options before consultation with their specialist as part of shared decision-making [52].
A further study focused on knee osteoarthritis prevention, describing a self-management lifestyle intervention for young to middle-aged rural-dwelling women that incorporated messaging to provide key behavior reminders [38].

RA Studies
Of the 5 studies on RA, 2 (40%) used message reminders as part of a motivational counseling intervention to reduce sitting time [37,48,56], and 1 (20%) focused on physical activity behavior change with messaging used for coaching, prompts, reminders, and monitoring of physical activity program adherence [51,75].A further study assessed the effects of text messages on medication adherence [32].One study collected data using text or app-based messaging for symptom or disease monitoring and patient-reported outcome measures [31].
In a study that recruited women with chronic widespread pain (80% met the American College of Rheumatology criteria for fibromyalgia), text messaging was used to prompt diary completion and allow participants to exchange short messages with their therapist.The diary information was used by therapists to inform patient care [35,47].A second guided imagery study also focused on people with fibromyalgia used text messaging to remind participants to practice their imaging exercises together with randomly selected reinforcement messages [50].
A study on patients with osteoporosis and nontraumatic fractures used text messaging to provide patients with treatment advice based on a validated fracture assessment tool and assessed whether the advice provided subsequently changed primary care physician management of their fracture [49].
Finally, one study described the use of social media messaging (WeChat) for people with ankylosing spondylitis, with messaging used for appointment reminders, for communication between physicians and patients, to record follow-up information, and for patients to provide feedback [54].

Multiple Musculoskeletal Conditions or Pain Sites
A total of 10 studies focused on multiple musculoskeletal conditions or pain sites (n=1, 10% each on the neck or back [64], neck, shoulder, or back [66], and chronic knee or low back pain [LBP] [67]).A total of 50% (5/10) of the studies recruited participants with a range of musculoskeletal problems typically seen in the general population [36,60,61,65], and 20% (2/10) of the studies recruited adults with chronic pain but not pain exclusively of musculoskeletal origin [62,63].A further study focused on chronic musculoskeletal pain in veterans [81].
For neck and back pain, one study described the use of an artificial intelligence-enabled app that implemented evidence-based guidelines for self-management, with messaging provided within the app to remind participants to exercise and provide contact with the treating team [64].A second study on workers with neck, shoulder, or back pain also described the use of artificial intelligence, wherein a chatbot provided messages with exercise instructions and suggestions for symptom improvement [66].One study focused on chronic knee XSL • FO RenderX or LBP described a digital care program incorporating sensors and an app that allowed participants to communicate with a personal coach via SMS text messaging and app-based messaging [67].
Another 20% (2/10) of the studies included adults with chronic pain but not exclusively pain of musculoskeletal origin [62,63].The first included patients being treated by a hospital-based pain management service for a range of conditions (LBP; cervical or upper-extremity, lower-extremity, abdominal or pelvic, and head or face pain; and multiple pain sites, with pain of ≥4 on a 0-10 scale).Participants used an app that incorporated reminders to complete daily assessments and also provided 2-way messaging [63].The second study, with similar wide-ranging pain sites, used automated text messaging to prompt skill practice as part of an internet-delivered CBT program for chronic pain [62].
Regarding patients attending hospital physiotherapy services for a range of musculoskeletal problems, 10% (1/10) of the studies examined whether SMS text messaging could increase home exercise compliance [36].In this study, compliance with exercises was encouraged via motivational SMS text messages sent by the physiotherapist.Similarly, the use of messaging to encourage home exercise compliance was described in a study on patients with musculoskeletal problems attending a chiropractic clinic [60].
In the physiotherapy outpatient setting, the use of SMS text message reminders to reduce clinic nonattendance was described in 10% (1/10) of the studies [61].
A total of 20% (2/10) of the studies focused on specific populations.The first, a community-based study, aimed to improve the physical activity of older adults (aged ≥60 years, most of whom had musculoskeletal problems) and used social media messaging (WhatsApp) to inform participants of scheduled walks and promote social interaction between participants [65].The second study focused on a chronic musculoskeletal pain program in veterans and used behavior change messaging for stress management and adoption of healthy sleep practices and to increase engagement and retention in the program [81].
A total of 38% (3/8) of the studies described the use of 1-or 2-way messaging with a health coach, physiotherapist, or sports scientist for support, encouragement, and participation reminders as part of self-management programs [27,70,71].

Neck Pain
Only 3% (1/40) of the studies focused specifically on neck pain.This study described a behavior change intervention for office workers with chronic neck pain incorporating weekly messages about caring for their pain with information about the importance of exercise and to provide encouragement to complete prescribed exercises [74].

Other Conditions
A total of 3% (1/40) of the studies, on patients with frozen shoulder recruited from an orthopedic outpatient clinic, used messaging to provide reminders, encouragement, and education to promote shoulder exercise compliance [30].

Overview
In this section, we report findings related to the design and development of messaging interventions.Because patient preferences, where accommodated, were generally addressed through participatory or co-design, we have reported the results of review questions 2 and 3 together.The findings are presented in three groups: (1) information found in papers specifically focused on the design and development of messaging interventions, (2) information found in mHealth design papers where some aspect of messaging was described alongside other mHealth functions, and (3) incidental design and development information found in papers that reported the results of messaging or mHealth interventions.The design-specific papers are shown in Table 4 and Figure 3 [85], behavior change theories [86], and normalization process theory [87] support system for LBP c (self-BACK) • During the development process, patients and health professionals (eg, physiotherapists and psychologists) were interviewed on their experience managing LBP.Educational content was reviewed by clinicians and researchers.

•
Patient case data (baseline information, physical activity monitoring, and weekly patient-reported health and adherence outcomes) were used to generate motivational notifications to encourage physical activity.Little messaging-specific design information was provided.

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A participatory design [88] was used.The team consisted of researchers, women, physicians, other health care professionals, and app designers.
• Messaging used to communicate the results of a bone density scan (DXA d ) to ry design and development of an mHealth app for women with newly diagnosed osteoporosis

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The iterative participatory app design process was somewhat unclear and described as commencing with 3 workshops (first, to generate ideas; second, to review wireframe designs; and third, to discuss the overall design content), followed by the creation of the design, feedback from users, women and coordinate their follow-up appointment with their general practitioner.development of a prototype, laboratory tests and feedback, adjustment, and final development.Messaging-specific design and development considerations were not described.
Nelligan et al [79], 2019-comprehensive description of the  [19,[89][90][91][92][93][94].The authors sage library to support adherence used a previous scoping review [95] that mapped barriers and facili-cise, with adaptive messages to home exercise for people with knee OA e tators against the Theoretical Domains Framework [96].Furthermore, the COM-B f framework for understanding health behavior [97] and the BCW g [97,98] were used throughout this phase.Previous work triggered by participant responses was used to identify messaging intervention functions appropriate for the SMS text messaging format [99].

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Phase 2: development of SMS text messaging functions and a message library The SMS text messaging functionality was guided by the literature [100].SMS text messages were automated and adaptive.Participants' self-reported exercise adherence triggered a BCT h .

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The content of the messages was codeveloped by 7 academics, 4 physiotherapists, and 1 person with knee OA.The authors based their messaging frequency on previous literature, which, while inconsistent, suggests that 3 messages per week tapered over time was appropriate [92,100].Examples are provided in appendixes accompanying the authors' article [79] and in Table 5.

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Design process (theory, method, and outcomes) Role of messaging Study, year

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Authors referred to the PSD i model [101].

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Structured interviews to identify patient preferences for features in a hypothetical app and their motivations for selecting those features • Limited messaging-specific information provided; however, reminders were rated highest in terms of desired features (medication and also posture).Praise and reward messages were considered less important, and social interaction features were rated the lowest.

• Messaging as a component in an app •
To provide medication or postural reminders Geuens et al [77], 2019-identified feature preferences and motivations for a hypothetical selfmanagement app for chronic arthritis

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Iterative development process involving researchers, health professionals, app designers, and patient representatives over 3-week "sprints" of development; user testing; reiteration; and, finally, pilot-testing • After a review of the literature and consensus meetings, it was determined that motivation enhancement techniques such as reminders could increase the intervention effect.

•
The Fogg Behavior Model [102], persuasive design [103], and daily push notifications to remind users of their goal and provide education on OA

Papers Focused Specifically on Messaging Design and Development
A total of 4% (2/47) of the papers comprehensively described the design and development of SMS text messaging interventions for knee osteoarthritis [79] and back pain [83].

An SMS Text Messaging Intervention to Support Home Exercise Adherence for People With Knee Osteoarthritis
In 2019, Nelligan et al [79] comprehensively described a formal two-phase process to (1) identify behavior change targets and (2) design a library of SMS text messages to support adherence to home exercises for people with knee osteoarthritis.The development was guided by the recommended steps for developing text messaging-based programs for health behavior change published by Abroms et al [100] in 2015.
The first phase of development, comprising 3 stages, focused on target behavior, barriers, facilitators, and behavior change techniques using the Behavior Change Wheel framework [97,98].Stage 1 drew on the literature to define the problem in behavioral terms, explaining the behavioral target and context and the barriers and facilitators for people with knee osteoarthritis in terms of participating in exercise mapped to domains in the Theoretical Domains Framework [96].Barriers and facilitators relevant to the target behaviors were organized using the Capability, Opportunity, and Motivation-Behavior model for behavior change [97].Stage 2 mapped barriers and facilitators to select intervention functions and behavior change techniques appropriate for implementation using SMS text messaging [93].In stage 3, behavior change techniques for each function were identified from the Behavior Change Technique Taxonomy (version 1) [99].
The second phase involved the development of SMS text messaging functionality, specifically, a message library of content and determination of message frequency and level of interaction.Messaging content was derived by taking each barrier-or facilitator-linked behavior change technique identified in the first phase and constructing a relevant SMS text message.Message content was derived with input from 12 participants (1 person with knee osteoarthritis, 7 researchers, and 4 physiotherapists).In total, 3 authors derived the final message bank.A fourth author reviewed the final SMS text message wording to ensure that it was consistent with the Behavior Change Wheel mapping process and the identified behavior change techniques.The final message bank was organized into a 24-week schedule, assessed using literacy tools for readability, and tested by the authors for functionality and errors.
Author-provided examples of the mapping process and resulting SMS text message content for example barriers and facilitators are shown in Table 5.
Table 5. Example barrier and facilitator mapping process, abridged from Nelligan et al [79].
Resulting SMS text message content BCT c [99] Intervention function [99] TDF b domain [96] COM-B a category [97] Barrier mapping "[Name], it can be hard to remember.We suggest making the exercises a habit.Set aside the same time each day to do them.It's much harder to forget when something is a daily routine."

A Messaging Self-Management Intervention for LBP
In 2019, Fritsch et al [83] described the co-design process used to derive a bank of evidence-based lifestyle-focused messages for an LBP self-management text messaging intervention.
The authors used an iterative 2-phase co-design approach based on a framework used to design prevention messages for patients with cardiovascular disease previously published by Redfern et al [106] in 2014.
Phase 1 consisted of two 2-hour workshops intended to develop the concept, initial content, and messages.Workshop participants were researchers, clinicians with specific knowledge related to LBP, and consumer representatives from the support group Musculoskeletal Australia.At the first workshop, participants identified important domains relevant to LBP (exercise, education, mood, use of care, sleep, and medication) through reference to an evidence-based consumer resource (Managing your pain: An A-Z guide; Musculoskeletal Australia).The second workshop was focused on identifying sources of content for messages and duration, frequency, and timing of messages.Identified sources of content were relevant peer-reviewed literature, Australian and international clinical practice guidelines for LBP, and consumer group patient educational resources.Message frequency (4 messages per week) and timing (9 AM, 12:30 PM, 4 PM, and 6 PM) were based on previous work in coronary heart disease [107].The development team considered that an intervention program duration of 12 weeks would be appropriate, with exercise domain messages being sent twice per week (emphasizing the importance of remaining active) and 1 message sent per week for each of the other domains.This phase of the development process was also informed by previous work on factors related to engagement, perceived usefulness, behavior change, and delivery preferences for patients with coronary heart disease [105].
Following the workshops, a team comprising 2 researchers and 2 consumer representatives drafted evidence-based behavior change messages following the same theoretical approach by Redfern et al [106].Messages were focused on education, motivation, or behavior change in the domains of providing information or encouragement; prompting about consequences, intention formation, monitoring self-behavior, and barrier identification; advice about setting graded tasks; and strategies aimed at relapse prevention and the use of prompting and cues.The team drafted an initial set of 82 positively phrased messages (by domain: 40 exercise messages, 10 education messages, 10 mood messages, 8 use of care messages, 7 sleep messages, and 7 medication messages) to take forward to the second phase of development.
In the second phase, the authors used a web-based survey of leaders in the field of LBP management to assess the appropriateness of the message content, gather opinions on the likelihood that the messages would be clinically effective, and make recommendations for message content improvement.The mean score for the messages from the expert review was 8.30/10.Messages with a score of <8/10 (34%) were modified in response to accompanying feedback.Subsequently, consumers scored each text message on utility of content, understanding, and language acceptability.Text messages with a consumer review score of <12/15 (31%) were revised according to feedback (mean score 12.5/15 points).Most frequently, consumer feedback focused on making the content more specific and less technical and including more examples.

Papers Describing the Design and Development of Messaging Within mHealth Apps
A total of 9% (4/47) of the papers described the design and development of more general mHealth interventions, where those interventions contained some use of messaging (alongside other mHealth features) for people with knee or hip osteoarthritis [80] and back pain [82], pain self-management for veterans [81], and women newly diagnosed with osteoporosis [76].In total, 2% (1/47) of the papers focused on feature preferences for an app to support the self-management of chronic arthritis [77].
In each case, the design of the overall intervention was typically well described; however, the design of the content, timing, and frequency of the messaging components was not described in detail (Table 4).Because these papers provided little useful XSL • FO RenderX messaging-specific design and development information, we do not discuss them any further.

Incidental Design and Development Information Contained in Papers Reporting the Results of mHealth Interventions
We found little useful design-related information contained within the papers describing results of interventions.Typically, the papers described the purpose and behavior of the messaging component within their intervention, but the design processes used to determine message content, timing, and frequency were described incidentally or not at all (studies shown in Tables 6  and 7) [30,35,36,38,47,50,60,62,63,65,66,72,74].For example, one paper provided examples of messages intended to provide encouragement, education, or motivation but provided no explanation of how these were derived [30].Similarly, some papers (4/47, 9%) made a passing reference to co-design processes involving patients and clinicians but provided limited detail [37,48,55,56].Some papers (17/47, 36%) described the use of messaging adaptivity (ie, dynamic system-initiated changes to the delivery of messaging to personalize content, frequency, or timing of messages based on automated or manual triggers) or individualization.Triggers for adaptivity included self-reported exercise adherence [79], automated physical activity data derived from wearables [57,68,73], self-reported data [54,66,71], personalized goals [37,48,55,56], and manual adaptivity triggers initiated by study personnel [31,63] and health coaches [26,27,67,70].However, in these papers, no substantial detail was provided on the design considerations or processes related to the development of the intervention's adaptive behavior.3 months (105) Experimental study; for patients with chronic pain using an app to record their progress, does 2-way Jamison et al [63], 2017

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Frequency of use • Patient perceptions (more appealing, easier to use, easier to navigate, and less bothersome) • Pain (BPI i ) supportive messaging, compared with no messaging, increase use or improve measures of pain or mood?

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Activity interference (PDI j ) • Favored controls: participant perceptions of the re-• Mood (HADS k ) sponsiveness of providers to their reports 7 days (213) Experimental study; for patients with knee osteoarthritis, does delivering education via an inter-Timmers et al [52], 2018 Perceived knowledge l active mobile app, compared with standard education, increase patients' knowledge of their illness and treatment options?
6 weeks (38) Experimental study; for patients with knee osteoarthritis, do messages containing information Bartholdy et al [53], 2019 • Time spent physically inactive, standing, and moving (accelerometry) • None and advice about the importance of performing daily activity, compared with no messages, lead to improved levels of activity?6 months (166) Experimental study; for patients with rheumatoid arthritis, does using automated messages for enhanced monitoring, compared with routine care, improve disease activity and remission and quality of life?Kuusalo et al [31], 2020 12 weeks (94) Experimental study; for workers with neck and shoulder stiffness and pain or LBP u , does an AI v -assisted interactive health promotion system that operates through a mobile messaging app, compared with usual workplace exercise routine, lead to an improvement in musculoskeletal symptoms?
Anan et al [66], 2021 a NRS: numeric rating scale.l Customized scale (actual perceived level was measured on a 0-36 scale, or perceived level was measured on a 0-25 scale).
m Customized scale for change in self-reported physical activity (included no change, less time, or 0-3.5 more times compared to baseline).
n Knee Injury and Osteoarthritis Outcome Score.The active control condition was not well described.

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Participants in both arms received 2 reminders each week via SMS text messaging prompting them to practice the guided imagery exercise.

weeks (80)
Molinari et al [50], 2018-assessed the efficacy of using guided imagery to have patients with fibromyalgia picture their best possible selves • Participants found the dynamic recommendations easier to adopt than the static generic recommendations.All participants found the recommendations "helpful."

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Walking duration during the dynamic phase was greater than in the static phase (+4.9 min/d); no significant differences in pain ("Likert" scale; 0-10) and nonwalking exercise (min) were found.

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Qualitative feedback included that participants wanted notifications in the moment and adaptivity in relation to the weather or weekend days in addition to information related to the relationship between pain and activity levels.

Studies Comparing the Use of Messaging With an Alternative
Of the 11 studies that directly compared messaging to an alternative, 9 (82%) had an experimental design and 2 (18%) were observational.In most cases, the comparator or control condition was no messaging or treatment as usual, with outcome measures varying by the intent of the intervention.Of these 11 studies, 3 (27%) [30][31][32] were described in the previous review on the effectiveness of text messaging interventions on the management of musculoskeletal pain [22], and the remainder were not, likely because they did not meet the inclusion criteria or were published later [49,52,53,[60][61][62][63]66].
Overall, the outcomes either favored the messaging condition or were equivocal.
Examples of outcomes favoring messaging interventions included improved knowledge of the illness and the available treatment options and physical activity for knee osteoarthritis [52,53], improved medication adherence and physical functioning for RA [31,32], improved attendance to outpatient physiotherapy [61] and engagement with general practitioner [49], and improved exercise compliance for frozen shoulder [30] and mixed musculoskeletal conditions [60].However, despite participants sometimes reporting messaging as acceptable [62] or appealing [63], and while improved pain intensity was found in participants with neck and shoulder pain and LBP [66], some studies (4/40, 10%) reported equivocal findings for important patient outcomes such as time spent physically active [53], pain [53,63], and quality of life [31,53].
In no studies did the primary outcome favor the control condition.In only one study, a secondary outcome (clinician responsiveness) favored the control condition.In this study, patients with chronic pain recorded their progress using an app, with intervention recipients also having access to messaging with their clinician (controls could report progress but had no messaging).Control participants perceived their clinicians to be more responsive to their progress reports [63].
No studies reported economic outcomes.
The studies are summarized in Table 6.
The results of efficacy and effectiveness were mixed, but because messaging was embedded within a larger mHealth intervention, it was not possible to isolate the messaging-specific effects from the overall intervention effects.
A total of 8% (2/24) of the studies reported economic outcomes-avoided surgery costs associated with a digital education program for chronic knee pain, in which messaging was used for coaching or peer support and program engagement reminders [26], and reduced travel time associated with a self-management mHealth tool for ankylosing spondylitis, in which social media messaging was used for communication between physicians and patients [54].
While it was not possible to isolate messaging-specific effects, these studies are included for completeness and summarized in Table 7.

Principal Findings
To our knowledge, this is the first study to comprehensively map how mobile messaging has been used in the treatment and self-management of musculoskeletal conditions.We mapped the conditions and purposes for which messaging has been used and the approaches used to design and develop messaging interventions and summarized the evidence of efficacy, effectiveness, and economics from both experimental and observational studies.Our intent was to draw together all the available relevant information to help inform the future design of messaging interventions for people with musculoskeletal conditions and identify research gaps.
While previous reviews in this area are few, this work builds on 3 existing syntheses of the effectiveness of messaging interventions for people with musculoskeletal conditions.One review focused specifically on text messaging interventions for musculoskeletal pain [22].The review included studies across a range of musculoskeletal problems and included both studies in which messaging was added to and compared with usual care (findings of positive effects only on exercise and medication adherence) and studies in which messaging was a component of a larger intervention (reporting some small effects on pain intensity, function, care-seeking behavior, exercise and medication adherence, and quality of life).Overall, the quality of the evidence was low.The 2 other reviews focused more generally on digital health for managing musculoskeletal conditions [23] and mHealth interventions for people with RA [46].
The notable absence of studies reporting negative outcomes may suggest publication bias.The lack of economic studies is also concerning; no messaging-specific studies reported economic outcomes.While, of the 40 studies, 2 (5%) digital or mHealth studies with messaging components did report XSL • FO RenderX economic outcomes, including avoided surgery costs and reduced travel time [26,54], the embedded nature of messaging means that it is not possible to attribute the observed savings specifically to the messaging components.While a previous review has shown messaging to be cost-effective in some circumstances, there is no information on the economic effects on musculoskeletal pain conditions; in cases in which messaging interventions are shown to be effective, further studies should be conducted to assess their economic effects [22,108].
We identified studies describing the use of messaging across a range of musculoskeletal conditions, with rheumatic diseases representing almost half (19/40, 48%) of the included studies, of which two-thirds (13/19, 68%) focused on osteoarthritis and RA.Somewhat surprisingly given its high population prevalence, back pain was represented by less than a quarter of primary studies (9/40, 23%).A further quarter of the studies (10/40, 25%) addressed multiple musculoskeletal conditions, but most (30/40, 75%) targeted single musculoskeletal conditions and pain sites despite evidence that musculoskeletal conditions often do not occur in isolation (eg, in Australia, 64% of people with back pain and 74% of people with arthritis have at least one other chronic condition) [3].
More than 80% of the included primary studies (34/40, 85%) focused on the use of prompts and reminder messages to foster positive behavior change at the individual level, most commonly in combination to encourage movement (eg, to increase physical activity, reduce sitting time, and improve compliance with prescribed exercise); compliance with prescribed medication; the practice of coping skills; and the meeting of personal goals.While a small number of studies (10/40, 25%) described the use of unidirectional or 2-way messaging with a health coach or exercise or sports scientist for support and encouragement, more studies (11/40, 28%) described the use of automated and unidirectional messaging, which, while economical on resources, may limit effectiveness in fostering behavior change.
While most studies (34/40, 85%) focused on influencing individual behavior change, there appears to be limited research into the use of messaging to improve treatment or self-management at the broader system level (eg, to improve health care processes, handover communication, and continuity of care between providers).One study on RA used SMS text messaging-based monitoring of medication adherence and disease progression to inform follow-up nurse contact but found no difference in the primary outcome of remission [31].A second study on a digital health platform for ankylosing spondylitis management consisting of a patient and physician portal and 2-way chat via social media reported improvements in the proportion of patients with inactive disease and an avoidance of 29.1% of in-person clinic visits [54].Future studies could focus on addressing the gaps in knowledge on more process-or system-focused interventions.
Overall, we found limited information about messaging design.
One study (1/40, 3%) used development processes previously described by Redfern et al [106], which, while originally focused on cardiovascular event prevention messaging, have since been more widely adopted and adapted in the co-design of text messaging interventions, including for diabetes prevention [109], endometriosis support [110], and support after breast cancer treatment [111].Similarly, one study (1/40, 3%) used guidance for the development and testing of messaging in health behavior change developed by Abroms et al [100].
Only 4% (2/47) of the papers provided comprehensive information about message design and development [79,83] and highlighted the importance of taking a formal approach and having a theoretical underpinning and meaningful consumer involvement.Beyond these 2 papers, design was typically poorly described or not described at all, and many projects appeared to leapfrog from concept to implementation with a limited or absent design phase, perhaps not recognizing the importance of formal design for subsequent adoption.
While some papers (8/47, 17%) did describe elements of participatory design or co-design, some papers (4/47, 9%) provided limited detail or had limited consumer involvement, or in some cases, consumers were involved after the design had already been conceived by researchers and clinicians.In most cases, we found that papers described the theoretical basis underlying their intended behavior change well, but consistent with a previous review [22], we found few detailed descriptions of the process through which the content, timing, and frequency of the messages were derived.This remains an important weakness in the musculoskeletal literature specifically and has been identified more generally by others [100,106].Further work should be conducted to elicit preferences regarding these processes from people across the spectrum of musculoskeletal conditions.
The strengths of this review include our comprehensive search strategy and the inclusion of a wide range of studies and designs, providing a rich map of the literature expanding the insights provided by previous effectiveness-focused reviews.A limitation is that we focused specifically on the use of messaging in patient care and self-management, and it is possible that there are other messaging applications relevant to people with musculoskeletal conditions.However, we made this review as broad as possible within available resources.Because a comprehensive synthesis was time-consuming and we last conducted the searches in 2022, there may be important, more recent studies that we missed in this review.Similarly, resources did not allow us to review the gray literature.

Conclusions
In conclusion, messaging has been used for the care and self-management of a range of musculoskeletal conditions with generally favorable outcomes reported.Nonetheless, there are areas that should be addressed by future research to improve the quality of intervention design, which will hopefully translate into uptake and sustainability.First, preferences related to messaging content, timing, and frequency should be further explored specifically among people with musculoskeletal conditions, eliminating the reliance on information from other disciplines.Second, teams should incorporate digital intervention design expertise, follow formal design processes, and clearly describe design considerations and processes used.Finally, in cases in which messaging interventions are shown to be effective, further studies should be conducted to assess

Figure 1 .
Figure 1.PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart-article selection process.*No registers were searched; **No automation tools were used; MSK: musculoskeletal.
c VH: very high.d Mobile health design paper.
e H: high.f Messaging-specific design paper.g Messaging provided using a social media app.
h M: medium.

Figure 3 .
Figure 3. Overview of 8 papers describing aspects of design and development of messaging.The circled numbers represent the number of papers.MSK: musculoskeletal.

"
Did you prioritize your exercises this week and get them done?Then reward yourself, [name]!Sticking to an exercise program for this long is a real accomplishment that deserves celebrationB: Capability, Opportunity, and Motivation-Behavior. b TDF: Theoretical Domains Framework.c BCT: behavior change technique.
b CBT: cognitive behavioral therapy.c RMDQ: Roland-Morris Disability Questionnaire.d PHQ-9: 9-item Patient Health Questionnaire.e GAD-7: 7-item Generalized Anxiety Disorder Scale.f WBPQ: Wisconsin Brief Pain Questionnaire.g Calculated as days answered "yes" to exercise/total days in the intervention.h VAS: visual analog scale.i BPI: Brief Pain Inventory.j PDI: Pain Disability Inventory.k HADS: Hospital Anxiety and Depression Scale.

Table 1 .
Characteristics of review papers related to messaging for people with musculoskeletal (MSK) pain conditions.

Table 2 .
Findings of review papers related to messaging for people with musculoskeletal (MSK) pain conditions.

Table 3 .
Characteristics of primary studies related to messaging for people with musculoskeletal (MSK) pain conditions.

Table 4 .
Papers focused on messaging design and development and patient preferences.

Table 6 .
Messaging-specific intervention studies-efficacy and effectiveness.
Disease Activity Score-28 for Rheumatoid Arthritis, Health Assessment Questionnaire, erythrocyte sedimentation rate, and C-reactive protein.

Table 7 .
Mobile health (mHealth) studies with an embedded messaging component.