This systematic review provides a chronological overview of how mhealth research has evolved with changes in mobile technologies. The review involved a PubMed search complemented by manual searching of all issues of the Journal of Medical Internet Research and Telemedicine Journal and eHealth, from inception to January 2015. Articles reporting the evaluation of mhealth interventions in any patient group for any health-related outcomes were analysed without restrictions on the study design. A total of 3476 publications were obtained from the PubMed search and manual searching of eHealth journals. Analysis was based on an abstract review of 515 (14.8%) original research articles, which fulfilled preset inclusion criteria. Three distinct time periods were identified on the basis of mobile devices used in mhealth research. Personal digital assistants (PDAs) dominated mhealth research in the years before 2007 (17 of 33 articles, 51.5%). Basic and feature phones were the main methods of mhealth intervention from 2007 to 2012 (95 of 193 articles, 49.2%). After 2012, smart devices (smartphones, tablet PCs and iPod touches) were highly used in mhealth research (173 of 289 articles, 59.9%). Despite a growing focus on infectious diseases and maternal and child health in the most recent years, non-communicable conditions continued to overshadow the trend of mhealth research. Overall, mHealth research has evolved over the past decade in terms of the mobile devices employed, health conditions addressed and its purpose. While chronic medical conditions have clearly been the focus of mhealth research, a shift in trends is expected as the application of mhealth interventions spreads to other under-studied areas. Future research should continue to leverage on the advancements and ubiquitous nature of mobile devices to make healthcare accessible to all.
- mHealth research
- mobile devices
- mobile technologies
- smart devices
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A little more than a decade ago, the term ‘mobile health’ (mhealth) was coined to describe the application of mobile devices (MDs) and related technologies in healthcare provision.1 Although this term has been in use since 2003, few experts in the field agree on its scope and definition.1 ,2 According to the WHO Global Observatory for eHealth, mhealth is “medical and public health practice supported by MDs, such as mobile phones, patient monitoring devices, personal digital assistants (PDAs), and other wireless devices.”2 In addition to the MDs mentioned in this definition, smartphones, portable media players and tablet personal computers (tablet PCs) have important applications in mhealth.3 Examples of the functionalities of these devices that are used in healthcare include, but are not limited to: short message services (SMS), paging, automated sensing, mobile applications (apps), media capabilities and videoconferencing.3 ,4 For purposes of this review, the term ‘mhealth’ is used to mean clinical and public health activities involving MDs.
As the major component of mhealth, MDs have evolved a lot since the 1973 introduction of the first mobile phone, the DynaTac.5 The first time introductions of the PDA and smartphone (the IBM Simon Personal Communicator) in 1992, iPhone in 2007 and iPad in 2010 are some of the important milestones in this regard.6–8 In recent years, MDs are progressively becoming ubiquitous and have significant contributions in day-to-day life.9 As far as the use of MDs in healthcare is concerned, the ubiquity of mobile phones and the recent advancements in wireless and smartphone technologies are making mhealth even more appealing.10 Reports from the first quarter of 2014 show that there were about 100 000 mhealth apps listed in the two major app stores (Apple and Android).11 Moreover, the annual revenue of the health-related mobile apps market is projected to reach more than US$26 billion by 2017 from its value of 2.4 billion in 2013.11
In an effort to tap into the potential of mhealth, there has been an increase in the amount of research in recent years.12 As a result of this increase, there were numerous attempts to systematically review and document the benefits of mhealth, focusing mainly on specific devices and/or health conditions.3 ,12 ,13 However, little is known about whether mhealth research evolved with changes in MD innovations. This review thus aims to answer the following questions. Did mhealth research evolve with innovations in mobile technologies? If so, how has it evolved in terms of the trends in the type of technology, medical interventions and health conditions addressed?
A PubMed search was conducted in November 2014 using keywords identified on the basis of a preliminary review of the literature. The PubMed search was re-run in January 2015 in order to include all the articles published in 2014. The keywords used were a combination of terms representing MDs and terms representing the application of technology in healthcare (see online supplementary appendix 1). Moreover, all issues of the Journal of Medical Internet Research and Telemedicine Journal and eHealth, prior to January 2015, were manually searched.
Article selection and review process
On the basis of the title review, journal articles written in English and with relevant content to mhealth were compiled for further analysis. After removal of duplicates, an abstract review was conducted to identify articles for further analysis based on the following inclusion criteria: MD intervention should be the main intervention in the study, articles should report the evaluation of mhealth interventions in patient care or public health and the study should be published before 1 January 2015. Literature reviews and articles reporting reviews of mobile apps with no testing on individuals, health professionals and patient perception studies, description of prototype MD systems and the use of MDs in the training of health professionals were excluded.
Classification of the purposes and functionalities of MDs
Generally, MDs were classified into mobile phones, smart devices, PDAs and other devices. While mobile phones referred to basic and feature phones (mobile phones with internet and media functionalities but without the advanced features of a smartphone), smart devices comprised smartphones, tablet PCs, iPod touch or any combination of these devices. Pagers, devices with wireless communication capabilities, wearable devices and a combination of multiple MDs were classified under the category of ‘other devices’. The categorisation of MDs was based on the classifications given by authors of the articles included in the review. Since the term mobile phone is a generic term referring to basic and smartphones, the full texts of articles that identified the MD used as a ‘mobile phone’ were reviewed to identify the brand used. If the authors reported specific brands (eg, iPhone), the device was categorised into an appropriate class (ie, smartphones).
The MD functionalities were classified into six types: app, SMS, automated sensing, media, voice call and videoconferencing, and other functionalities. While SMS, voice calls and video conferencing were straightforward for classification, operational definitions were used for the rest of the classes. Any software designed to be installed on MDs (whether it was on smartphones, feature phones or PDAs) was classified as apps. Automated sensing systems included the use of different electronic devices that connected (either wired or wirelessly) to MDs that processed the data. The use of accelerometers and gyroscopes embedded in MDs was also included in this category. The media category included the use of MDs to record, view, analyse and/or transfer medical images and videos. The category ‘other functionalities’ was used to classify the combined use of multiple functionalities and relatively uncommon MD functionalities, such as missed calls (buzzing) and alarm systems.14 ,15
The purposes of mhealth interventions were categorised into five major classes: health promotion and disease prevention, diagnosis, treatment, monitoring and support for health services (see online supplementary appendix 2). Moreover, health conditions addressed by mhealth interventions were broadly categorised into: non-specific conditions, non-communicable conditions (including risk factors and protective health behaviour); infectious diseases and other conditions (see online supplementary appendix 3).
Selection and characteristics of studies
The PubMed search retrieved 3277 articles, out of which 1491 had potentially relevant content to the objective of this review. In addition, 199 mhealth-related articles were identified by the manual search, making the total number of articles considered for review to be 1690. After exclusion of duplicates and articles that did not fulfil the inclusion criteria, the abstracts of a total of 515 studies (30.5%) were analysed (see online supplementary appendix 1).
On the basis of the types of MDs predominantly used in mhealth research over the years, distinct trends were observed in different time periods (figure 1). The time before 2007 was characterised by a higher number of articles reporting the use of PDAs. From 2007 to 2012, mhealth research was largely concentrated on the healthcare uses of mobile phones. In recent years (2013 and 2014), the direction of mhealth research geared more towards the use of smart devices such as smartphones, tablet PCs, iPod touch or any combination of these devices. While MD functionalities used in mhealth followed the trends in the devices (figure 1), there was a clear trend of targeting non-communicable conditions (figure 2). On the contrary, no clear trend was seen in the purpose of mhealth interventions (figure 2). In the sections that follow, specific features of each time period are described in terms of the MD functionalities used, the health conditions addressed and the purpose of mhealth interventions.
Years before 2007
A total of 33 (6.8%) articles were from the years before 2007 with the earliest article published in 1993.16 Seventeen (51.5%) articles reported the use of PDAs for healthcare followed by those using mobile phones (10 articles, 30.3%) and other devices (5 articles, 15.2%). PDA apps were used in 12 (36.4%) of the articles followed by automated sensing systems (8 articles, 24.2%). However, SMS was used in only 3 (9.1%) of the articles published in this period (table 1). The top 2 purposes of mhealth interventions were as support for health services (17 articles, 51.5%) and monitoring (11 articles, 33.3%) (table 2). Reported in 13 (39.4%) articles, non-communicable conditions had a big share of the conditions addressed by mhealth interventions (table 3). Among the non-communicable conditions, diabetes mellitus was the most reported (4 articles, 30.8%, online supplementary appendix 4).
Apart from the predominant use of PDA apps for the main purposes of support for health services17–19 and for monitoring different aspects of health,20 ,21 there were some emerging trends of using special features of MDs. Notable in this regard were the early use of camera phone and smartphones in mhealth. An article published in 2004 reported the use of a 0.11 megapixel camera phone for assessment of injuries of the fingers in the emergency room.22 The first and only smartphone-based mhealth study identified in this review used a Nokia 7650 Symbian smartphone connected via Bluetooth to a child's glucometer and programmed to automatically send the measurement results to the parents by means of SMS.23 The only wearable device identified in this period was used for fall detection in elderly participants. It was a small radio pager-sized device to be worn on the waist or chest area and was reported to trigger a radio signal to a community alarm system on detection of the fall.15
Years from 2007 to 2012
A substantial increase in the amount of mhealth research occurred during this time period, with a total of 193 (37.5%) articles published in the 6 years. Almost half of the articles (95/193 articles, 49.2%) reported the use of mobile phones. While the use of PDAs did not keep up with the pace of the other MDs, the use of smart devices in mhealth research was starting to proliferate with 57 (29.5%) articles reporting their use (table 1). Despite the use of smartphones, in a majority of the articles (46, 80.7%) that reported employing smart devices, first-time uses of tablet PCs24 and iPod touch25 were reported in this period. Moreover, unique devices were also identified. One notable article in this regard reported the use of a mobile phone containing an inbuilt device to measure capillary blood glucose for self-monitoring of diabetic control.26 Another article reported evaluation of a PDA-type glucometer (Accu-Check Inform System, Roche) with wireless capabilities to transfer test data to a server.27
Overall, apps were the most commonly applied mhealth interventions in this period (52 articles, 26.9%), followed by SMS-based (42 articles, 21.8%) and media-based (34 articles, 17.6%) interventions (table 1). Apart from these trends, the uses of smart device-based videoconferencing28 ,29 and media-based interventions using camera phones mounted on a microscope eyepiece to facilitate the diagnosis of different conditions in settings with a lack of trained staff30 ,31 were notable introductions in this period.
Regarding the purpose of interventions, most were used for patient monitoring (58 articles, 30.1%), followed by support for health services (50 articles, 25.9%) and diagnosis (33 articles, 17.1%)-related interventions (table 2). A majority of the articles (106, 54.9%) targeted non-communicable conditions (see online supplementary appendix 4). It was also in this period that researchers started to employ mhealth interventions for reproductive, maternal and child health (see online supplementary appendix 4).
Years after 2012
This time period included articles published in 2013 and 2014. A total of 289 articles were retrieved from the 2 years out of which 173 (59.9%) were based on smart devices (table 1). There were also three articles that reported the use of alphanumeric pagers as a means of communication and alerting systems for professionals.32–34 Apps were the most widely used mhealth interventions (140 articles, 48.4%), followed by SMS (57 articles, 19.7%) (table 1). Notable smartphone and mobile phone functionalities used in this time include: WhatsApp (the instant messaging app) as a means of communication between sugeons;35 smartphone-based test reader platforms for the diagnosis of leprosy in blood samples;36 and the use of a missed call/buzzing functionality, as a means of an appointment reminder for newly diagnosed HIV patients.14
A comparable number of articles reported that mhealth interventions were employed for support for health services (73 articles, 25.3%), monitoring (67 articles, 23.2%) and diagnosis (63, 21.8%)-related purposes (table 2). A majority of the articles reported the use of mhealth interventions on non-communicable conditions (167 articles, 57.8% followed by conditions categorised under the ‘other conditions’ category (48 articles, 16.6%; table 3). In this time period, the use of mhealth interventions was starting to spread to understudied conditions such as: H1N1 epidemic,37 rabies,38 as well as polio.39
This review showed that evaluation of MDs for healthcare applications evolved with the predominant mobile technology at each time period. mHealth research was mainly dependent on PDAs in the years before 2007. This was in agreement with the fact that PDAs had a widespread popularity, especially with the young medical professionals in developed nations of the early 2000s.40 It was then apparent that mHealth research started leveraging on the ever-increasing ownership of mobile phones in the general population after the mid-2000s (from 2007 to 2012).41 In the most recent years, mhealth research started to focus more on smart devices, in congruence with the high level of smartphone penetration globally.9 Despite the paucity of articles reporting their evaluation, pagers were still being used in recent mhealth research. This was not surprising since pagers are still used in certain healthcare settings due to their reliability.42
Apps were the ever increasingly used MD functionalities in mhealth research throughout the three periods described in this review. The ease of installing apps in all kinds of MDs, ranging from feature phones to high-end smartphones, could have caused this increase in app research.43 However, an increasing amount of research in recent times reported the use of SMS-based and media-based interventions with the increase in the number of mobile phone-based and smartphone-based interventions. The limited use of SMS in the early 2000s for mhealth research could partly be explained by the fact that SMS were generally not that popular at the time.44
PDAs were generally restricted to ownership by professionals in contrast to the current high penetration rate of smartphones in the general public.45 This might be part of the reason for the inclination of mhealth interventions, before 2007, towards support for health services. None of the articles reviewed from this period were targeting health promotion and disease prevention activities. However, there is an increased amount of research focusing on health promotion, disease prevention and diagnosis in recent years. In this regard, the widespread penetration of MDs in the general public and their increased image resolutions and screen sizes partly explain the current trends.46
Generally, non-communicable conditions and their risk factors were the focus of mhealth research throughout the time periods in our review. As with other aspects of healthcare, there was lesser focus on neglected diseases of poverty.47 This could be explained by the fact that most of the articles (328, 63.7%) came from North America and Europe (see online supplementary appendix 5). However, an increasing emphasis was seen on reproductive, maternal and child health, HIV/AIDS and other infectious diseases in recent years. The rise in project funding, in an effort to meet the Millennium Development Goals (MDG5), partly explains the increase in attention to these conditions.48 In contrast, a reduction was seen in the number of articles targeting chronic conditions, such as diabetes. Similarly, cancer and chronic respiratory conditions were studied in a relatively lesser number of mhealth articles compared to the magnitude of their contribution to global morbidity and mortality (see online supplementary appendix 4).49
Future advancements in mobile technologies are expected to provide more flexibility in the use of MDs for healthcare by way of functionalities embedded in the devices or connectivity to external devices.46 Potential improvements in smartphone operating systems and cloud computing systems in the next few years are projected to fuel a wider range of mhealth research and its applications.50 Moreover, the increasing penetration of mobile networks in previously unreachable areas and the availability of smartphones in many parts of the developing world can certainly be considered a great opportunity in this regard.
The main limitations of this review were the fact that only one database was searched and only articles published in English were evaluated. Since mhealth is a multidisciplinary domain cutting across healthcare/medical and technological sciences, research articles targeting mhealth interventions could be published in a wide variety of journals, ranging from general medicine and public health journals to more specialised journals focusing on information and communication technologies in healthcare. Inclusion of other journal databases and articles published in other languages could possibly result in more articles that could affect the trends reported in this review. Furthermore, since mhealth is a rapidly changing domain, research trends in this area could potentially change as the proportion of healthcare professionals and patients who are digital natives increases. As such, we advocate that future reviews on mhealth research target more journal databases, and such reviews should be conducted on a regular basis, so that any differences in mhealth research trends could be identified. Nonetheless, our review has managed to identify a large number of articles in mhealth research and thus the current research trends in the mhealth domain. We believe that our review will add to the paucity of literature describing research trends in mhealth.
This review has shown that mhealth research has evolved with advances in MDs from predominantly PDA-based interventions to those dependent on basic and feature phones and, recently, to smart devices. However, basic MD functionalities such as SMS remain important in mhealth research. The mhealth domain has also evolved from its early inclination to support system for health services (eg, clinical decision support systems, drug information sources and systems to augment documentation of patient medical records) to more diversified purposes, including preventative care, health promotion, diagnosis, treatment and monitoring. While chronic medical conditions have always been the focus of mhealth research, an increase in attention to non-communicable conditions has been observed recently. Since the variety of MDs and their functionalities continue to proliferate, future mhealth research should continue to change so that healthcare can ultimately be accessible to all.
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- Data supplement 1 - Online supplement
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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