Purpose: Mobile health or mHealth research has been growing exponentially in recent years. However, the research on mHealth has been ad-hoc and selective without a clear definition of the mHealth domain. Without a roadmap for research we may not realize the full potential of mHealth. In this paper, we present an ontological framework to define the mHealth domain and illuminate a roadmap.
Methods:We present an ontology of mHealth. The ontology is developed by systematically deconstructing the domain into its primary dimensions and elements. We map the extent research on mHealth in 2014 onto the ontology and highlight the bright, light, and blind/blank spots which represent the emphasis of mHealth research.
Findings: The emphases of mHealth research in 2014 are very uneven. There are a few bright spots and many light spots. The research predominantly focuses on individuals’ use of mobile devices and applications to capture or obtain health-related data mostly to improve quality of care through mobile intervention.
Conclusions: We argue that the emphases can be balanced in the roadmap for mHealth research. The ontological mapping plays an integral role in developing and maintaining the roadmap which can be updated periodically to continuously assess and guide mHealth research.
Mobility is central to the notion of participatory healthcare. It provides freedom from temporal and spatial constraints to both providers and recipients of healthcare, and thus facilitates their participation in healthcare. Not surprisingly, the domain of mobile health, or mHealth as it is commonly denoted, has garnered much attention in recent years as its application has come to permeate the healthcare industry. The concept of mobility has evolved from the physical transportation of healthcare staff and equipment to simply transporting information using modern technologies ; a novel paradigm that begins in telemedicine and telehealth , giving rise to the concept of eHealth with mHealth as its subset . The smartphones and associated technologies represent the next stage of the evolution in ‘transporting information to transform healthcare’ , and consequently mobility of and participation in healthcare.
There has been an explosion of research on mHealth in the last few years. There are altogether 808 mHealth articles with abstracts indexed in PubMed between 2013 and January 2015 when the data was collected, of which 364 (45%) are from 2014. Similarly, the number of mHealth articles indexed in Scopus has seen an exponential increase since 2010 . The numbers are likely to grow unabated.
Research on mHealth has been selective, largely focusing on the mobile applications or apps, based on several reviews of the domain. “Most studies narrowly focused on text messaging systems for patient behavior change, and few studies examined the health systems strengthening aspects of mHealth.”  This statement aptly reflects the narrow focus of the mainstream mHealth research. The domain of mHealth however transcends mobile applications or text messaging. It stands at the crossroads of information and communication technologies (ICT) and patientand outcome-oriented healthcare. Regardless, the landscape of mHealth research is scattered with narrowly-focused research niches. Most studies emphasize behavior change, intervention, or self-monitoring for adherence to treatment or medication [6–12] while others focus on adoption or specific characteristics of mobile applications [13–20]. A few others examine the use of mobile technologies in prevention, diagnosis, treatment, patient care, and education in general [21–24].
Amidst this rapid explosion of interest, the definition of the mHealth domain remains unclear. Researchers have focused selectively on different parts of the whole, neglecting the ‘big picture’. This selectivity results in fragmentation of the research agenda; the sum of the parts simply falls short of making the whole. There is a need to articulate and make the combinatorial complexity of mHealth visible to facilitate effective research on mHealth systems . “The current confusion in the nomenclature and classification hinder telemedicine research . . . it frustrates our efforts to reach a reasonable understanding of what we already know and what we need to know. Equally important, it impedes progress toward development and implementation of a research agenda geared toward reaching answers to questions regarding the true benefits and costs of telemedicine.” [26,p. 492]With these concerns in mind, we use an ontology to frame and represent the complexity of mHealth. The ontology can be used both prospectively to construct a roadmap to guide research and retrospectively to map and assess present research in the domain. The ontology and the mapping can be updated periodically to refresh the roadmap.
We will first review some key definitions of mHealth and then logically deconstruct the concept using an ontology. We will then describe how the ontology can be used to define the domain of mHealth, and how it can be extended, reduced, refined, and coarsened to adapt to the evolving technology and environment for healthcare. Last, we will delineate how the ontology can be used to map the state-of-the-research and the state-of-the-practice in mHealth, discover the gaps in research and between research and practice, and formulate a strategy to bridge those gaps and generate synergy—all with the goal of making the whole greater than the sum of its parts.
1.1. Definitions of mHealth
The term mHealth and its variant m-Health date back nearly twenty years, a period that has seen their definition shift within both the landscape of health technologies and the discipline to which they were applied. The definitions suggest the dimensions and elements of the mHealth domain but do not comprehensively denote the domain. We will present and discuss these definitions, and in the next section draw upon them to construct an ontology of mHealth.
Istepanian, Jovanov and Zhang  define mHealth [they spell it m-Health] as “mobile computing, medical sensor, and communications technologies for healthcare.” As the title of their article suggests, they envision it leading to “. . .seamless mobility and global wireless health-care connectivity.” In a more recent article they suggest the “. . .evolution of m-health towards targeted personalized medical systems with adaptable functionalities and compatibility with the future 4G networks.” [28,italics in the original] Their definition focuses on the hardware and networks driving the transition, and the potential impact on healthcare in general due to enhanced connectivity. It is a technology-based definition.
Akter, D’Ambra and Ray  define “mHealth. . . as the use of mobile communications such as PDAs and mobile phones for health services and information. Researchers have recently extended the definition of mHealth by focusing on any wireless technologies (e.g., Bluetooth, GSM, GPRS/3G, Wi-Fi, WiMAX) to transmit various health-related data content and services through mobile devices, including mobile phones, smartphones, PDAs, laptops and Tablet PCs.” Further, they suggest that the ubiquity of mobile phones “is a central element in the promise of the mobile platform for healthcare.”  Like the previous, this definition is singularly technology-based.