Abstract
Digital phenotyping consists of moment-by-moment quantification of behavioral data from individual people, typically collected passively from smartphones and other sensors. Within the evolving context of precision health, digital phenotyping can advance the use of mHealth-based self-management tools and interventions by enabling more accurate prediction for prevention and treatment, facilitating supportive strategies, and informing the development of features to motivate self-management behaviors within real-world conditions. This represents an advancement in self-management science: with digital phenotyping, nurse scientists have opportunities to tailor interventions with increased precision. In this paper, we discuss the emergence of digital phenotyping, the historical background of ecological momentary assessment, and the current state of the science of digital phenotyping, with implications for research design, computational requirements, and ethical considerations in self-management science, as well as limitations.
Introduction
The role of mobile health (mHealth) interventions in self-management research is expanding exponentially. These interventions, which deliver self-management support via the internet, short messaging services, and mobile applications, show promise for improving self-management outcomes (Hamine, Gerth-Guyette, Faulx, Green, & Ginsburg, 2015; Tinschert, Jakob, Barata, Kramer, & Kowatsch, 2017; Whitehead & Seaton, 2016). Examples of the major benefits of mHealth interventions include tracking and monitoring of symptoms for better symptom control (Whitehead & Seaton 2016), on-going education and support for disease management (Heinrich, Schaper, & de Vries (2015), and access to timely communication with healthcare providers (Lancaster et al., 2018; Vorungati, Grunfeld, Makuwaza, & Bender, 2017). However, the rapid development and deployment of mHealth technology has so far resulted in a one-size-fits-all approach. Current mHealth interventions are generally developed for the average person, with insufficient emphasis on differences among individuals or on the impacts of mHealth interventions on health outcomes (Noah et al., 2018). This lack of precision tailoring can reduce a patient’s engagement and even engender a reactive mistrust of intervention technology (López, Green, Tan-McGrory, King, & Betancourt, 2011; O’Leary, Vizer, Eschler, Ralston, & Pratt 2015). Nevertheless, if such problems with engagement can be resolved, mHealth still holds great promise for supporting patients’ self-management.
In this article, we present the concept of digital phenotyping, a technique that can help realize the promise of mHealth interventions for self-management. We provide current definitions of digital phenotyping and suggest potential applications of this technique for self-management in the precision health era. We include a discussion of digital phenotyping’s emergence, the influence of ecological momentary assessment (EMA), and the current state of the science of digital phenotyping, with implications for research design, computational requirements, and ethical considerations in self-management science—as well as limitations.
Current mobile technology, with the increasing availability of affordable smartphones and wearable devices including sensors, has resulted in the profuse collection of physiological or behavioral data. Instead of periodic cross-sectional assessments of self-reports that are prone to recall bias and under-reporting, this technology allows measurement in situ of an individual’s physiological parameters such as heart rate or calories expended or of an individual’s behavioral patterns such as daily activity or sleep. This moment-by-moment quantification of one’s passively collected physiological and behavioral data is termed digital phenotyping (Torrous, Kiang, Lorme, & Onnela, 2016; Onnela 2016). The tailoring of mHealth interventions through personalization can be facilitated by digital phenotyping and can help predict health outcomes and stratify risk for individual patients (Onnela, 2016).
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, 2018) has defined a behavioral or psychological phenotype as “a pattern of behavior or psychological characteristics that are measurable/quantifiable and distinct (explains individual variation).” Onnela and Rauch (2016) have argued that the digital phenotype (Jain, Powers, Hawkins, & Brownstein, 2015), a static digital construct that can define the attributes of an individual’s behavior (e.g., the digital profile of an insomniac could include night-time posts on the social media platform Twitter), is distinct from digital phenotyping, which is a dynamic construct that alludes to passive, ongoing, multidimensional digital measurement of the individual’s behaviors (e.g., clicks on the phone, time of texts, sleep tracking, etc.). Both constructs, however, are useful for the self-management of chronic conditions. Another term that describes digital patterns in behavior and physiology is digital biomarkers, defined as the “objective, quantifiable, physiological, and behavioral data that are collected and measured by means of digital devices, such as embedded environmental sensors or wearables” (Piau, Wild, Mattek, & Kaye 2019, p. 1). Our definition of digital phenotyping is inspired by the NIDDK’s definition; here we are proposing digital phenotyping of patterns of health behaviors and personal characteristics that are measurable, quantifiable, and distinct; digital phenotyping can thus explain individual variation in self-management.
Precision health—targeted, predictive, personalized healthcare—has the potential to improve the efficiency and efficacy of chronic disease management interventions. The digital data for health behaviors and parameters, such as, for example, times in the day when physical activity interventions are most amenable for certain sets of individual characteristics, can inform precision mHealth interventions (Kitsiou, Paré, Jaana, & Gerber, 2017). In developing such interventions, one must gain an understanding of patterns in a subpopulation’s adoption of, engagement with, and response to mHealth interventions. Moreover, to optimize an individual’s self-management responses to precision mHealth interventions, one must also determine the optimal intervention dose in terms of frequency and intensity for the individual. Digital phenotyping can enable more accurate prediction for treatment and prevention, facilitate supportive strategies for adherence and maintenance of change, and inform the development of mHealth intervention features in order to “effectively and efficiently identify who will maximally benefit” (Hickey et al., 2019, p. 463). Together, multidimensional data gathered passively through digital phenotyping, such as patterns in daily activity, calories expended, heart rate, body temperature, sleep, sweat, and mood, can quantify an individual’s physical behaviors, which is often a focus in self-management interventions. Interventions promoting self-management can then be concentrated on those who will benefit, sparing expense and potential unintended adverse consequences for those who will not. As knowledge in the field accumulates, more personalized tailoring methods can be applied on the basis of different digital phenotypes. Efforts are already underway to provide recommendations for developing and evaluating digital behavioral interventions based on varying responses to required durations and dimensions of engagement, pace of interventions, efficiency, effectiveness, and cost (Michie, Yardley, West, Patrick, & Greaves 2017; Voils et al., 2014).
Emergence of Digital Phenotyping
Historically, digital phenotyping derives from methods associated with ecological momentary assessment (EMA), the repeated measurement of an individual’s behaviors and experiences in real time within the context of the individual’s natural environment (Shiffman, Stone, & Hufford, 2008). EMA’s benefits include minimizing recall bias, maximizing ecological validity, and enabling the study of factors or processes that influence behavior in the real world (Shiffman et al., 2008). Early tools for EMA ranged from written diaries and telephone interviews to electronic diaries and physiological sensors (Bertz, Epstein, & Preston, 2018), all of which required active participant input. Since EMA was originally used by behavioral scientists to study mental health issues (e.g., addictive behaviors such as smoking, drinking alcohol, or overeating, as well as mood affects), it is not surprising that digital phenotyping was first applied by behavioral scientists in research on mental health.
The current emergence of digital phenotyping is tied to the proliferation of wearable sensors and mHealth applications (apps). Revenue for the sale of wearable devices for the year of 2019 is estimated at more than $3 billion in the U.S., with nearly 40 million users (Statista, 2019). Over 318,000 health apps are available from the top app stores worldwide, with more than 200 being added each day (IQVIA, 2017). Nearly half (48%) of healthcare consumers are using mHealth apps, up from just 16% in 2014 (Francis, 2018). Current innovations in wireless connectivity have enabled mobile phones to seamlessly capture real-time behavior data from behavior-tracking physical devices and sensors by routing the data to mobile phones (Zanella, Bui, Castellani, Vangelista, & Zorzi, 2014). However, mHealth and sensor tools can suffer from limitations in quality, usability, accuracy, or sustained interest (Liew, Zhang, See, & Ong, 2019; Rosenberger, Buman, Haskell, McConnell, & Carstensen, 2016), which suggests that one should proceed cautiously in the application of digital phenotyping in mHealth. For example, the popular augmented reality mHealth game Pokemon Go was purported to promote fun physical activity, but it suffered a rapid drop-off in gameplay rate within a single season. Nevertheless, the increased use of smartphones and wearable sensor devices offers opportunities to track individuals’ self-management routines and behaviors, which can inform the tailoring of self-management interventions through digital phenotyping.
Digital Phenotyping for Precision Tailoring
Nursing science has made significant contributions to self-management science, especially by focusing on populations that suffer from health disparities (Grey, Knafl, & McCorkle, 2006; Grady, 2017; Riegel & Dickson, 2008). Nurse scientists have advanced ways to tailor self-management interventions to address the unique features of target populations. For example, nurse scientists have tailored self-management intervention protocols for cultural sensitivity (Brown, Garcia, Orlander, & Hanis, 2017; H. Kim, Song, Han, Kim, & Kim, 2013; M. T. Kim et al., 2015) and have adapted them for levels of literacy (Rosal et al., 2011), cognitive ability (Stuifbergen et al., 2012), and physical function (Bragina et al., 2017). Influenced by the premises of precision health initiatives, nurse scientists now have a new opportunity to expand the methodology of tailoring (Hickey et al., 2019) through the use of digital phenotyping.
Unfortunately, however, generalizations based on demographic characteristics such as age, ethnicity, or income level have led to stereotypical assumptions about certain subpopulations’ ability to engage with mobile technology-assisted self-management interventions. Such stereotypical assumptions can worsen disparities in access to quality care (O’Leary et al., 2015). Yet the assumption that low English proficiency and older age are barriers to the use of mobile technology interventions has been invalidated by recent studies (Huh et al., 2018; Radhakrishnan et al., 2016). In addition to demographic variables, individual characteristics helpful for personalizing or tailoring mHealth interventions can include physical and cognitive functioning (Bateman et al., 2017; Koo & Vizer, 2019); affective states of fatigue, anxiety, and depression (Moberg, Niles, & Beermann, 2019); sleep (Moon et al., 2017); health literacy (Rosal et al., 2011); digital literacy/eHealth literacy (Kreps, 2017); and attitudes toward the adoption of mHealth technology (Cajita, Hodgson, Lam, Yoo, & Han, 2018). All of these characteristics can inform our understanding of individuals’ responses to mobile technology interventions for the self-management of chronic conditions. Digital phenotyping may help explain why individuals provided with the same self-management technology intervention and clinical diagnosis may respond to the intervention in different ways and have dissimilar outcomes for health and quality of life (QOL). As the design of mHealth tools and interventions becomes adapted and more personalized to meet the unique needs of individuals, “the ‘self’ in self-management will become a focal point for tailored interventions” (O’Leary et al., 2015, p. 992).
Digital Data Collection for Phenotyping
There is no shortage of digital data that can be obtained through both passive and active data collection for the purpose of digital phenotyping. Passive forms of measurement record individuals’ behaviors at a granular level, removing the response burden typically involved in active self-monitoring (Skinner et al., 2017). Smartphones and connected sensors can passively monitor self-management behavior patterns related to physical activity, sleep, medication adherence, eating, smoking, or mobility, through changes in steps, calories, heart rate, hand movements, medication absorption, position of lids of pill boxes, or body temperature. The research platform Beiwe, for example, includes a smartphone app designed specifically for digital phenotyping. This app passively collects metadata minute-by-minute, using GPS, WiFi, accelerometry, text and telephone logs, and times for screen on and off (Onnela & Rauch, 2016). The latest versions of smartwatches can measure activity, sleep, and EKG, with caveats for validity of intense physical activity (Khushhal et al., 2017) or sleep (Lee, Byuon, Keill, Dinkel & Seo, 2018), as well as a lack of regulatory approvals for use of most smartwatches as medical devices (Larson, 2018). To provide actionable insights about addiction or lifestyle behaviors for preventive management, other smartphone apps can collect data related to hand movements associated with smoking or eating (Chun, Bhattacharya, & Thomaz, 2018; Senyurek, Imtiaz, Belsare, Tiffany, & Sazonov, 2019; Skinner, Stone, Doughty, & Munafò, 2019).
Continuous monitoring and improved tracking of an individual’s symptoms, activities, sleep, behaviors, and treatment adherence can allow precise determination of triggers in disease exacerbations and a reliable assessment of a self-management intervention’s effectiveness. Such data can define a digital phenotype for self-management to better understand intrapersonal factors that influence an individual’s self-management behaviors, the effectiveness of specific features in the individual’s self-management intervention, and resulting health outcomes. Despite challenges, mHealth interventions thus hold great potential to facilitate self-management interventions on a large scale, even though the interventions focus precisely on specific individuals.
State of the Science of Digital Phenotyping
In September 2019, our search of the PubMed and CINAHL databases using the terms “digital phenotype” or “digital phenotyping” yielded a total of 82 journal articles, 12 of which reported original studies on the application of digital phenotyping for chronic diseases. All 12 studies employed smartphone apps, with the most commonly collected data being from self-report surveys (10 studies), followed by activity and movement (8); screen time, phone call and text logs (7); geo-location (6); and sleep (3). Across the 12 studies, 9 variables were examined in relation to mental health functioning (e.g., stress levels or depressive symptoms). Although none of the 12 studies included nurses as authors, research centers led by nurse scientists have begun the training and mentoring of nurse researchers to design studies that utilize digital data for informing insights on self-management behaviors (Hickey et al., 2019).
Digital phenotyping has primarily been applied to classify or stratify individuals by levels of daily stress, depressive symptoms, or suicidal thoughts (Kleiman et al., 2018; Saeb, Lattie, Schueller, Kording, & Mohr, 2016; Sarda, Munuswamy, Sarda, & Subramanian, 2019; Wahle, Kowatsch, Fleisch, Rufer, & Weidt, 2016). Algorithms based on dense digital data were used to predict onset of mental health crises such as relapses in schizophrenia or increased severity of mood disturbances (Barnett, Torous, Staples, Sandoval, et al., 2018; Choet al., 2019; Zulueta et al., 2018). These algorithms were also used to explore the validity of objective digital data collected from mobile or wearable devices in comparison with self-reported mental health symptoms or status (Rohani, Faurholt-Jepsen, Kessing, & Bardram, 2018; Sano et al., 2018) and to obtain insights for providing timely support for mental illness crises (Wahle et al., 2016). Three of the 12 studies reported on the application of digital phenotyping for physiological diseases. These applications included stratifying treatment compliance levels of children with asthma (Jaimini et al., 2018), quantifying the progression of amyotrophic lateral sclerosis (Berry et al., 2019), and quantifying mobility and QOL in people with spine diseases (Cote, Barnett, Onnela, & Smith, 2019). In other studies, the term digital phenotyping was not specifically used, but the concept has been applied in forecasting glucose levels on the basis of typical self-monitoring practices in individuals with diabetes (Albers et al., 2017).
Digital Phenotyping Considerations for Evaluating and Promoting Self-Management Behaviors
Research Study Designs
Evidence from digital phenotyping studies includes numerous repeated measures over time on individuals’ health behaviors obtained with digital tools (Vieira, McDonald, Araújo-Soares, Sniehotta, & Henderson, 2017). This requires research designs that test hypotheses and interventions at the individual level and that accommodate individualized sequences and strategies involved in adaptive intervention delivery (e.g., to reduce frequencies of alerts, switch incentives, increase the intensity of messages; Murphy, Lynch, Oslin, McKay, & TenHave, 2007). Study designs for just-in-time adaptive interventions (JITAIs) require a “sequence of decision rules that specify whether, how, when (timing), and based on which measures, to alter the dosage (duration, frequency or amount), type, or delivery of treatment(s) at decision stages in the course of care” (Almirall, Nahum-Shani, Sherwood, & Murphy, 2014, p. 262).
Conventional parallel-group randomized controlled trials (RCTs) can assess what is best on average for a given population, but they are limited with respect to the individual participant. Study designs such as n-of-1 trials or micro-randomized trials (MRTs) assess what is best for individual patients. Such designs are thus particularly well suited to precision health and to the emerging field of digital phenotyping (Lillie et al., 2011; Mirza, Punja, Vohra, & Guyatt, 2017). For JITAI trials, which adjust to the individual’s evolving status, n-of-1 trials and MRT designs (Klasnja et al., 2015; Klasnja et al., 2019) provide the rigor and processes necessary to elicit evidence for tailoring interventions at the individual level. Moreover, such designs incorporate key elements of RCTs that reduce bias, such as randomization (of intervention sequence) and blinding (of patients, care providers, outcome assessors, and data analysts). Interventions in which adaptations are delivered in a momentary way, usually by relying on data from smartphones or other mobile devices with sensors, are embedded within an MRT or n-of-1 trial design for testing and evaluation. Momentary interventions allow testing of the tailoring variables and the intervention components in the same trial, and they allow clinicians to develop the best decision rules based on research rather than a priori decisions (Murphy et al., 2007). Whereas RCTs evaluate interventions that have already been developed, individuals in MRTs are randomized hundreds or thousands of times over the course of the study, so that the trial can construct multicomponent interventions by assessing the effects of intervention components and their variance over time, as well as each individual’s context (Klasnja et al., 2015). In n-of-1 trials, on the other hand, interventions and the order of interventions are randomized multiple times within a person (Methodology Center, n.d.-a). In response to concerns about the generalizability of insights from n-of-1 trials, aggregated analysis of several n-of-1 trials is also a possibility (Vieira et al., 2017).
Such study designs, however, do have the downside of increased cost and complex logistics in assigning individuals to several interventions at multiple timepoints. Multiphase optimization strategy (MOST) is a research design framework in which many interventions are tested in phases before the most optimized interventions are carried out in an RCT (Collins, Murphy, & Stretcher, 2007; Methodology Center, n.d.-b). Such research design frameworks are most suited for evaluating multicomponent behavioral interventions, and can provide a balance between cost, complexity, and rigor. The sequential multiple-assignment randomized trial (SMART) is a special tool of MOST, in which a dynamic treatment regimen can be efficiently optimized by “identifying the best set of decision points, decision rules, treatment options, and tailoring variables” (Collins, Nahum-Shani, & Almirall, 2014, p.429). Although a full comparison of the different adaptive study designs is beyond the scope of this article, the JITAI resource page at The Pennsylvania State University and its cited articles provide good resources for designing such studies (Methodology Center, n.d.-a). Future digital phenotyping studies can provide further evidence on the feasibility and value of different study designs for evaluating longitudinal interventions with long follow-up periods and many repeated measures that can be adapted to the individual’s real-world conditions.
Analysis and Computation
Mobile and sensor-based tools have the potential to provide longitudinal, high-frequency, rich data from individuals’ everyday self-management behaviors—substantial quantities of data. Up to 1,000,000 data points per day have been obtained in studies that collect raw sensor data from smartphone-based tracking of individuals’ activities or behaviors (Barnett, Torous, Staples, Keshavan, & Onnela, 2018). Converting this vast amount of information into actionable insights for self-management behaviors necessitates the extraction of meaningful behavioral features from digital data as well as appropriate statistical analysis of associations of behaviors with relevant health outcomes (Barnett, Torous, Staples, Keshavan, & Onnela, 2018). Since digital phenotyping generates big data, machine learning algorithms and related statistical methods can be useful for inferences. Barnett, Torous, Staples, Keshavan, and Onnela (2018) have demonstrated the application of three statistical methods—mixed models, multiple comparisons of correlated tests, and dimension reduction for correlated behavioral covariates—for drawing valid conclusions in digital phenotyping studies. Table 1 presents a comparison of the three statistical methods with respect to use case scenarios, decisions about preferred options, and considerations for usage.
Table 1:
Approaches for Statistical Analysis of Digital Phenotyping Data
| Analysis Method | Use Case Scenario | Preferred Approach When: | Considerations during analysis |
|---|---|---|---|
| 1. Mixed models 1.1. Generalized estimating equations (GEE) 1.2. Generalized linear mixed models (GLMM) |
Correlations between daily behaviors and symptoms | 1.1. Model misspecification is high or outcome distribution is unknown. 1.2.Model misspecification is not severe and large numbers of observations are obtained for each subject; has higher accuracy. |
a. Random effect structures and computational considerations based on sample size b. Missing data: Data imputation prior to analysis of complete data, or multiple imputation approaches (Barnett & Onnela, 2016) |
| 2. Correction for multiple statistical tests to avoid the possibility of abundant false positive results 2.1. Family-wise error rate (FWER) 2.2. False discovery rate (FDR) |
Correlations between each self-reported outcome and a behavioral marker, requiring the need for many simultaneous statistical tests | 2.1. More conservative approach is needed, but may lead to high rate of false-negatives 2.2. More lenient approach is suited. May be more suited to the exploratory nature of current digital phenotyping studies |
Many outcomes and behavioral features can be highly correlated, so there is a need for correction of the assumption of independence of tests, to optimally reduce the rate of false negatives. |
| 3. Dimensionality reduction, to reduce the number of redundant predictors 3.1. Principal component analysis (PCA) or factor analysis 3.2. Least squares PCA |
Correlation blocks obtained by clustering of digital phenotyping predictors around a specific behavior type | 3.1. There are no missing values in the data 3.2. Data include some missing values. |
Block correlation structures can allay the potential of poor interpretability of transformed predictor variables. |
Implications of Digital Phenotyping for Self-Management Science
Smartphones and wearable devices capture both an individual’s behavior and environment (e.g., sleep, light, temperature). Therefore, digital phenotyping data can facilitate an understanding of how individuals perform behaviors (e.g., pace of activity or napping) in real time and in response to specific features of mHealth interventions (e.g., timing of alerts or notifications) under real-world conditions (Marsch, 2018). Digital phenotyping can also enable an understanding of the reactive effects of self-monitoring actions on behavior. Digital phenotyping data can inform guidelines for optimal dosage and for frequency and intensity of self-management behaviors that are realistic and relevant to an individual’s level of motivation, intrapersonal factors, and environment (Marsch, 2018). These behavior guidelines can inform the design of effective JITAIs that provide the right amount of self-management support to individuals precisely when it is most effective, in order to gradually advance the individual’s behaviors in a desired direction (Marsch, 2018; Nahum-Shani, Hekler, & Spruijt-Metz, 2015; Skinner et al., 2017). Such precise prescriptions for behaviors that individuals can actually attain are in line with precision health initiatives and can contribute to improved health outcomes.
Digital phenotyping also provides a novel approach to identify and predict as well as incentivize an individual’s self-management behaviors (Jain et al., 2015). For example, data from digital phenotyping can be used to address personal or environmental attributes that predict an individual’s need for human facilitators or technology brokers, such as community health workers or family members for mHealth-based self-management interventions. Digital phenotyping could also capture aspects of social support such as reactions to competition, intellectual stimulation, peer support, family support, and accountability to clinicians, or promote the perception of being accountable to a digital monitoring device that can motivate the specific individual. Digital phenotyping can inform structures and timing of incentives within a mobile digital device based on individuals’ interactions with the digital device (e.g., via voice, texts, alert frequency and timing, reminders; Torous, Onnela, & Keshavan, 2017). Finally, digital phenotyping can inform feedback messages from the device that support an individual’s engagement in self-management behaviors as well as in mHealth-based self-management interventions.
Insights from digital phenotyping studies can also inform the adaptation of mHealth technology interventions based on individuals’ responses to interventions in the presence of varying levels of physical or cognitive functioning (e.g., presence of physical disability or gait variances; varying levels of cognitive impairment). Subcultural influences (e.g., suburban vs. rural, caregivers, military) on responses to messages or preferences for incentives are still unclear. Digital phenotyping has the potential to provide insights on when individuals may be most receptive to messages providing information or support through mHealth self-management interventions (Marsch, 2018). Digital phenotyping research can develop algorithms that match specific intervention elements with individuals’ attributes and engagement in self-management behaviors, enabling the delivery of precise interventions to motivate behavior changes.
Ethical Implications
Traditionally, the term digital divide alludes to lower access to technology among those who face disparities due to lower socio-economic status, older age, or rural residency with little high-speed internet (Anderson & Perrin, 2019). This divide can be a significant barrier to scaling up digital self-management interventions and realizing digital phenotyping’s promise. However, the current global increase of mobile phone ownership offers low-cost possibilities for introducing digital self-management and thus empowering individuals (Huh et al., 2018). Seventy-seven percent of Americans now own smartphones, up from just 35% in 2011 (Pew Research Center, 2018). In the groups with a yearly income of less than $30,000, smartphone ownership drops to 67%, but it is over 80% in groups with incomes above that level (Pew Research Center, 2018). Although disparities in smartphone ownership remain, sweeping generalizations about lack of access to technology or lack of motivation among end users as core barriers to digital intervention adoption in underserved populations are no longer accurate (Bennet et al., 2014). Digital phenotyping studies can provide valuable insights on how to personalize mHealth interventions to support the self-management needs of diverse socio-economic groups and cultures (Huh et al., 2018).
The promise of digital phenotyping to achieve the aims of precision health initiatives for self-management can be realized only if individuals are willing to wear and engage with sensors or other devices that mHealth technology-assisted self-management interventions require (Skinner et al., 2017). Therefore, research on digital phenotyping can benefit greatly from user-centered design (Norman & Draper, 1986) and from usability studies that address the contexts, needs, and preferences of each user. Moreover, to reduce inequities traditionally associated with mHealth interventions, usability considerations are especially pertinent for tailoring digital phenotyping interventions for individuals with lower literacy or those who are differently abled (Veinot, Mitchell, & Ancker, 2018). Finally, the advancement of self-management science through digital phenotyping must not exclude the consideration of the human touch (K. B. Kim et al., 2016; Radhakrishnan, Jacelon, & Roche, 2012). Individuals with chronic diseases in nursing studies using technology interventions such as telehealth have articulated their acceptance for digital interventions as long as it does not completely replace human touch. The value-added benefit of digital phenotyping should be to accentuate the human touch, as opposed to diminishing it, by freeing up clinicians to spend more quality time with their patients. Insights provided by digital phenotyping might be most beneficial by helping to sort out contextual clues that support self-management, ultimately enhancing human touch.
Major ethical implications of digital phenotyping especially relevant today are implicated in issues of data ownership, security, and privacy. With the use of data acquisition tools in digital phenotyping studies come formidable challenges to protecting the privacy and security of individuals and their information. Geolocation data obtained through GPS and integrated with behavior data can have negative consequences if the data fall into wrong hands (e.g., of stalkers or criminals). Other unintended consequences might consist of decisions on health insurance and employment eligibility based on digital health behavior data, which might be sold to third parties by digital device companies. To demonstrate the value of digital phenotyping for self-management interventions, one must be able to ensure trust. It is imperative to provide individuals with ownership of their digital data, the right to grant access to view their data and any related application of their data, and the right to consent regarding which data they might share with researchers and clinicians as well as their family caregivers.
Several policy initiatives have been proposed and endorsed to protect individuals’ rights over their personal digital health data. The European Union has passed the General Data Protection Regulation (European Commission, 2018), which allows consumers to demand erasure of their personal information or prohibit companies from selling their digital data to third parties. Along the same lines, U.S. Senators Klobuchar and Murkowski have introduced the Protecting Personal Health Data Act (2019; see also Ackerman, Kraus, Ponder, & Tonsager, 2019), which proposes greater consumer control over how personal health data are utilized, as well as the right to delete and amend health data and to access a copy of one’s personal health data free of cost, in an accessible format. In addition, among other measures, the bill proposes a National Task Force on Health Data Protection to explore encryption standards, transfer protocols, and de-identification techniques. As of 2020, the California Consumer Privacy Act (Privacy, 2018) will require all internet of things devices that are made or sold in California (e.g., activity trackers, refrigerators, thermostats) to be equipped with unique passwords or to require users to set their own unique passwords. Forcing password measures on internet of things devices could prevent cybersecurity attacks that might be carried out by hijacking such devices and infecting laptop/desktop computers in the home (Information Privacy, 2019). In 2018, a similar bill at the federal level called the Internet of Things Cybersecurity Improvement Act was proposed by Senators Warner and Gardner, but it has yet to gain traction (Hawkins, 2018; Warner, 2017). The Food and Drug Administration’s software precertification program is an example of a regulatory mechanism to ensure that commercialization of digital health products is “high-quality, safe and effective while providing appropriate patient safeguards” such as protecting individuals’ rights over their digital data and their data’s applications (U.S. Food and Drug Administration, 2019, p. 1). It is imperative for researchers and clinicians to be aware of these policy initiatives to protect digital health data and ensure necessary data protections in their research and practice in order to realize the value of digital phenotyping ethically.
Limitations and Future Directions
Although advances in technology have vastly improved the capability of smartphones and sensors to collect behavioral data, there are still limitations to mHealth technologies’ ability to passively collect accurate information for certain critical behaviors, such as diet. For the foreseeable future, a need remains for digital phenotyping to be combined with traditional types of data collection. A meaningful area for research would be the development of methods to combine diverse sources and types of data including genomics or other omics data in such a way as to provide an interpretable picture of an individual’s self-management behaviors.
In self-management science, one must also acknowledge the merit of actively collecting data such as an individual’s self-reflection on his/her behavior in juxtaposition with digital phenotyping. Self-reflection on one’s own behavior is emerging as a major component of behavioral change, aided today by mHealth-based self-monitoring activities. The intensity of such active data collection should be commensurate with an individual’s optimal response burden.
Conclusion
Digital phenotyping holds the potential to enable researchers to realize the promise of mHealth-based self-management interventions within precision health initiatives. Digital phenotyping is a novel approach to identify and predict as well as incentivize individuals’ self-management behaviors within the context of their social, cognitive, and physical functioning under real-world conditions. However, the advancement of digital phenotyping in self-management must comply with ethical considerations as well as the demands of computation and research design. The data from digital phenotyping will also provide answers to missing gaps regarding intermediary ingredients in mHealth-based interventions that must be addressed to enable the interventions’ success in motivating self-management behaviors in individuals within real-world conditions.
Acknowledgment
Editorial support with manuscript development was provided by the Cain Center for Nursing Research and the Center for Transdisciplinary Collaborative Research in Self-Management Science (P30, NR015335) at The University of Texas at Austin School of Nursing.
Funding Sources
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Contributor Information
Kavita Radhakrishnan, Assistant Professor, School of Nursing, The University of Texas – Austin, 1710 Red River Street, Austin, TX 78701-1499, UNITED STATES.
Miyong T. Kim, La Quinta Centennial Endowed Professor, School of Nursing, The University of Texas – Austin, 1710 Red River Street, Austin, TX 78701-1499, UNITED STATES.
Marissa Burgermaster, Assistant Professor, Department of Population Health, Department of Nutritional Sciences, The University of Texas – Austin, 103 W 24TH ST, Austin, TX 78712, UNITED STATES.
Richard Allen Brown, Research Professor, School of Nursing, The University of Texas – Austin, 1710 Red River Street, Austin, TX 78701-1499, UNITED STATES.
Bo Xie, Professor, School of Nursing, School of Information, The University of Texas – Austin, 1710 Red River Street, Austin, TX 78701-1499, UNITED STATES.
Molly S Bray, Julian C. Barton Endowed Professor, School of Nutrition, Professor, Department of Pediatrics, The University of Texas – Austin, 103 W 24TH St, Austin, TX 78712, UNITED STATES.
Catherine A. Fournier, Robert Woods Johnson Fellow, Research Assistant, School of Nursing, The University of Texas – Austin, 1710 Red River Street, Austin, TX 78701-1499, UNITED STATES.
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