Predrag Klasnja's research while affiliated with University of Michigan and other places

Publications (114)

Article
Background: Physical inactivity is associated with numerous health risks, including cancer, cardiovascular disease, type 2 diabetes, increased health care expenditure, and preventable, premature deaths. The majority of Americans fall short of clinical guideline goals (ie, 8000-10,000 steps per day). Behavior prediction algorithms could enable effi...
Preprint
BACKGROUND Mental health difficulties among university students have been rising rapidly over the last decade, and the demand for university mental health services commonly far exceeds available resources. Digital interventions are seen as one potential solution to these challenges. However, as in other mental health contexts, digital programmes of...
Chapter
Mobile health (mHealth) interventions can improve health outcomes by intervening in the moment of need or in the right life circumstance. mHealth interventions are now technologically feasible because current off-the-shelf mobile phones can acquire and process data in real time to deliver relevant interventions in the moment. Learning which interve...
Chapter
This chapter offers a conceptual framework that ties together two domains of design decisions for digital therapeutics—those related to intervention design (i.e., which components or treatments to include) and those related to study design (i.e., how to test whether components or treatments work as intended). This framework is intended to help rese...
Preprint
Full-text available
In this technical note, we introduce an improved variant of nearest neighbors for counterfactual inference in panel data settings where multiple units are assigned multiple treatments over multiple time points, each sampled with constant probabilities. We call this estimator a doubly robust nearest neighbor estimator and provide a high probability...
Article
Full-text available
The ILHBN is funded by the National Institutes of Health to collaboratively study the interactive dynamics of behavior, health, and the environment using Intensive Longitudinal Data (ILD) to (a) understand and intervene on behavior and health and (b) develop new analytic methods to innovate behavioral theories and interventions. The heterogenous st...
Preprint
BACKGROUND Physical inactivity is associated with numerous health risks, including cancer, cardiovascular disease, type 2 diabetes, increased healthcare expenditure, and preventable, premature deaths. The majority of Americans fall short of clinical guideline goals (i.e., 8,000-10,000 steps per day). Behavior prediction algorithms could enable effi...
Article
Full-text available
Background There is a fundamental gap in understanding the causal mechanisms by which strategies for implementing evidence-based practices address local barriers to effective, appropriate service delivery. Until this gap is addressed, scientific knowledge and practical guidance about which implementation strategies to use in which contexts will rem...
Preprint
Full-text available
Digital Therapeutics (DTx) are increasingly seen as a promising way to provide safe, effective, accessible, sustainable, scalable, and equitable approaches to advance individual and population health. Developing DTx is inherently complex in that DTx may include multiple interacting components, such as tools to support activities like medication adh...
Conference Paper
Many individuals fail to engage in sufficient physical activity (PA), despite its well-known health benefits. This paper examines Model Predictive Control (MPC) as a means to deliver optimized, personalized behavioral interventions to improve PA, as reflected by the number of steps walked per day. Using a health behavior fluid analogy model represe...
Conference Paper
Insufficient physical activity (PA) is commonplace in society, in spite of its significant impact on personal health and well-being. Improved interventions are clearly needed. One of the challenges faced in behavioral interventions is a lack of understanding of multi-timescale dynamics. In this paper we rely on a dynamical model of Social Cognitive...
Conference Paper
This paper presents the use of discrete Simultaneous Perturbation Stochastic Approximation (DSPSA) to optimize dynamical models meaningful for personalized interventions in behavioral medicine, with emphasis on physical activity. DSPSA is used to determine an optimal set of model features and parameter values which would otherwise be chosen either...
Article
Background: Baseline physical activity in patients when they initiate cardiac rehabilitation is poorly understood. We used mobile health (mHealth) technology to understand baseline physical activity of patients initiating cardiac rehabilitation within a clinical trial to potentially inform personalized care. Methods: The Virtual AppLication-Support...
Article
Full-text available
Background: The US Preventive Services Task Force recommends blood pressure (BP) measurements using 24-h ambulatory monitoring (ABPM) or home BP monitoring before making a new hypertension diagnosis. Objective: Compare clinic-, home-, and kiosk-based BP measurement to ABPM for diagnosing hypertension. Design, setting, and participants: Diagnos...
Article
Full-text available
Background: Recent advances in mobile and wearable technologies have led to new forms of interventions, called “Just-in-Time Adaptive Interventions” (JITAI). JITAIs interact with the individual at the most appropriate time and provide the most appropriate support depending on the continuously acquired Intensive Longitudinal Data (ILD) on participan...
Article
Background In-person, exercise-based cardiac rehabilitation improves physical activity and reduces morbidity and mortality for patients with cardiovascular disease. However, activity levels may not be optimized and decline over time after patients graduate from cardiac rehabilitation. Scalable interventions through mobile health (mHealth) technolog...
Article
Just-in-time adaptive interventions (JITAIs) are time-varying adaptive interventions that use frequent opportunities for the intervention to be adapted-weekly, daily, or even many times a day. The microrandomized trial (MRT) has emerged for use in informing the construction of JITAIs. MRTs can be used to address research questions about whether and...
Article
Background Behavioral obesity treatment (BOT) is a gold standard approach to weight loss and reduces the risk of cardiovascular disease. However, frequent lapses from the recommended diet stymie weight loss and prevent individuals from actualizing the health benefits of BOT. There is a need for innovative treatment solutions to improve adherence to...
Article
Objective: Mobile technologies allow for accessible and cost-effective health monitoring and intervention delivery. Despite these advantages, mobile health (mHealth) engagement is often insufficient. While monetary incentives may increase engagement, they can backfire, dampening intrinsic motivations and undermining intervention scalability. Theor...
Preprint
BACKGROUND Behavioral obesity treatment (BOT) is a gold standard approach to weight loss and reduces the risk of cardiovascular disease. However, frequent lapses from the recommended diet stymie weight loss and prevent individuals from actualizing the health benefits of BOT. There is a need for innovative treatment solutions to improve adherence to...
Article
Background: To identify critical periods for just-in-time adaptive interventions (JITAIs), we measured time-varying correlates of drinking (e.g. stress, mood) daily to predict near-term alcohol use. Methods: Emerging adults (aged 17–24; n = 51) who reported past-month alcohol use used SARA, an app use designed to assess substance use, for 30 days....
Article
Full-text available
In mobile health (mHealth) smart devices deliver behavioral treatments repeatedly over time to a user with the goal of helping the user adopt and maintain healthy behaviors. Reinforcement learning appears ideal for learning how to optimally make these sequential treatment decisions. However, significant challenges must be overcome before reinforcem...
Article
1. Introduction We would like to thank the editor for making this a discussion paper. We are honoured that these three groups of researchers agreed to be discussants. Reading their discussions has been an enjoyable and thought-provoking journey for us. We organize our rejoinder by topic, as some topics have been discussed by multiple discussants....
Preprint
Full-text available
Just-in-time adaptive interventions (JITAIs) are time-varying adaptive interventions that use frequent opportunities for the intervention to be adapted--weekly, daily, or even many times a day. The micro-randomized trial (MRT) has emerged for use in informing the construction of JITAIs. MRTs can be used to address research questions about whether a...
Chapter
The field of mobile health (mHealth) focuses on the uses of mobile technologies to support the delivery of healthcare services and management of health in everyday life. mHealth tools range from clinical applications for remote patient monitoring and shared decision making to tools intended to help individuals better manage chronic conditions or ma...
Article
Full-text available
Despite the positive health effect of physical activity, one third of the world’s population is estimated to be insufficiently active. Prior research has mainly investigated physical activity on an aggregate level over short periods of time, e.g., during 3 to 7 days at baseline and a few months later, post-intervention. To develop effective interve...
Article
Background: Emotion regulation is a key transdiagnostic risk factor for a range of psychopathologies, making it a prime target for both prevention and treatment interventions in childhood. Existing interventions predominantly rely on workshops or in-person therapy-based approaches, limiting the ability to promote emotion regulation competence for...
Preprint
Full-text available
BACKGROUND Emotion regulation is a key transdiagnostic risk factor for a range of psychopathologies, making it a prime target for both prevention and treatment interventions in childhood. Existing interventions predominantly rely on workshop or in-person therapy-based approaches, limiting the ability to promote emotion regulation competence for chi...
Article
Full-text available
Background: Evidence-based interventions (EBIs) could reduce cervical cancer deaths by 90%, colorectal cancer deaths by 70%, and lung cancer deaths by 95% if widely and effectively implemented in the USA. Yet, EBI implementation, when it occurs, is often suboptimal. This manuscript outlines the protocol for Optimizing Implementation in Cancer Cont...
Article
Full-text available
Background Substance use among adolescents and emerging adults continues to be an important public health problem associated with morbidity and mortality. Mobile health (mHealth) provides a promising approach to deliver just-in-time adaptive interventions (JITAIs) to prevent escalation of use and substance use–related consequences. Objective This...
Article
Smartphone and wearable device use is rising broadly and can be leveraged for chronic disease management. Just-In-Time Adaptive Interventions (JITAIs) promise to deliver personalized, dynamic interventions directly to patients through use of push notifications from mobile devices. While JITAIs are a powerful tool for shaping health behavior, their...
Preprint
Full-text available
Despite the positive health effect of physical activity, one third of the world’s population is estimated to be insufficiently active. Prior research has mainly investigated physical activity on an aggregate level over short period of time, e.g., during 3 to 7 days at baseline and few-month later, post intervention. To develop effective interventio...
Article
Full-text available
Mobile health (m-Health) resources are emerging as a significant tool to overcome mental health support access barriers due to their ability to rapidly reach and provide support to individuals in need of mental health support. m-Health provides an approach to adapt and initiate mental health support at precise moments, when they are most likely to...
Article
Full-text available
Objective: Despite evidence that goal setting is valuable for physical activity promotion, recent studies highlighted a potential oversimplification in the application of this behavior change technique. While more difficult performance goals might trigger higher physical activity levels, higher performance goals might concurrently be more difficul...
Preprint
BACKGROUND Substance use among adolescents and emerging adults continues to be an important public health problem associated with morbidity and mortality. Mobile health (mHealth) provides a promising approach to deliver just-in-time adaptive interventions (JITAIs) to prevent escalation of use and substance use–related consequences. OBJECTIVE This...
Article
Advances in wearables and digital technology now make it possible to deliver behavioral mobile health interventions to individuals in their everyday life. The micro-randomized trial is increasingly used to provide data to inform the construction of these interventions. In a micro-randomized trial, each individual is repeatedly randomized among mult...
Article
Due to the recent advancements in wearables and sensing technology, health scientists are increasingly developing mobile health (mHealth) interventions. In mHealth interventions, mobile devices are used to deliver treatment to individuals as they go about their daily lives. These treatments are generally designed to impact a near time, proximal out...
Article
Mobile health is a rapidly developing field in which behavioral treatments are delivered to individuals via wearables or smartphones to facilitate health-related behavior change. Micro-randomized trials (MRT) are an experimental design for developing mobile health interventions. In an MRT the treatments are randomized numerous times for each indivi...
Preprint
In mobile health (mHealth) smart devices deliver behavioral treatments repeatedly over time to a user with the goal of helping the user adopt and maintain healthy behaviors. Reinforcement learning appears ideal for learning how to optimally make these sequential treatment decisions. However, significant challenges must be overcome before reinforcem...
Article
Full-text available
Clinical trials are a fundamental tool used to evaluate the efficacy and safety of new drugs and medical devices and other health system interventions. The traditional clinical trials system acts as a quality funnel for the development and implementation of new drugs, devices and health system interventions. The concept of a “digital clinical trial...
Preprint
BACKGROUND The majority of cigarette smokers want to quit someday but are not ready to commit to long-term abstinence. However, available smoking cessation treatments are not well-suited to meet the needs of these ambivalent smokers. Low-cost, high-reach mobile health (mHealth) interventions may be a cost-efficient means of offering assistance to a...
Article
Full-text available
Background: The majority of cigarette smokers want to quit someday but are not ready to commit to long-term abstinence. However, available smoking cessation treatments are not well-suited to meet the needs of these ambivalent smokers. Low-cost, high-reach mobile health (mHealth) interventions may be a cost-efficient means of offering assistance to...
Article
Bariatric surgery is the most effective treatment for severe obesity (body mass index >40), helping individuals lose, on average, 25%–29% of their body weight over the first year. However, many patients begin to plateau and regain weight within 12–24 months, and 20% of patients begin to regain weight within 6 months postsurgery. As physical activit...
Preprint
Just-in-time adaptive interventions (JITAIs) are time-varying adaptive interventions that use frequent opportunities for the intervention to be adapted such as weekly, daily, or even many times a day. This high intensity of adaptation is facilitated by the ability of digital technology to continuously collect information about an individual's curre...
Preprint
Although there is much excitement surrounding the use of mobile and wearable technology for the purposes of delivering interventions as people go through their day-to-day lives, data analysis methods for constructing and optimizing digital interventions lag behind. Here, we elucidate data analysis methods for primary and secondary analyses of micro...
Article
Full-text available
Background There is considerable scientific interest in finding new and innovative ways to capture rapid fluctuations in functioning within individuals with bipolar disorder (BD), a severe, recurrent mental disorder associated with frequent shifts in symptoms and functioning. The use of smartphones can provide valid and real-world tools for use in...
Preprint
BACKGROUND There is considerable scientific interest in finding new and innovative ways to capture rapid fluctuations in functioning within individuals with bipolar disorder (BD), severe, recurrent mental disorder associated with frequent shifts in symptoms and functioning. The use of smartphones can provide valid and “real-world” tools for use in...
Preprint
Objective: Despite evidences that goal setting is valuable for physical activity promotion, recent research pointed out a risk of oversimplification in the application of this behavior change technique. While more difficult goals might trigger higher physical activity levels, higher goals might concurrently be more difficult to achieve, which could...
Preprint
Full-text available
Mobile health (mHealth) applications are a powerful medium for providing behavioral interventions, and systematic reviews suggest that theory-based interventions are more effective. However, how exactly theoretical concepts should be translated into features of technological interventions is often not clear. There is a gulf between the abstract nat...
Article
With the recent proliferation of mobile health technologies, health scientists are increasingly interested in developing just-in-time adaptive interventions (JITAIs), typically delivered via notifications on mobile devices and designed to help users prevent negative health outcomes and to promote the adoption and maintenance of healthy behaviors. A...
Preprint
In mobile health (mHealth), reinforcement learning algorithms that adapt to one's context without learning personalized policies might fail to distinguish between the needs of individuals. Yet the high amount of noise due to the in situ delivery of mHealth interventions can cripple the ability of an algorithm to learn when given access to only a si...
Preprint
With the recent advancements in wearables and sensing technology, health scientists are increasingly developing mobile health (mHealth) interventions. In mHealth interventions, mobile devices are used to deliver treatment to individuals as they go about their daily lives, generally designed to impact a near time, proximal outcome such as stress or...
Article
Full-text available
Besides passive sensing, ecological momentary assessments (EMAs) are one of the primary methods to collect in-the-moment data in ubiquitous computing and mobile health. While EMAs have the advantage of low recall bias, a disadvantage is that they frequently interrupt the user and thus long-term adherence is generally poor. In this paper, we propose...
Chapter
Mobile health (mHealth) interventions can improve health outcomes by intervening in the moment of need or in the right life circumstance. mHealth interventions are now technologically feasible because current off-the-shelf mobile phones can acquire and process data in real time to deliver relevant interventions in the moment. Learning which interve...
Article
Full-text available
It is likely that you or someone you know is affected by a chronic health condition. For example, a staggering six in 10 adults in the USA are currently suffering from a chronic disease (National Center for Chronic Disease Prevention and Health Promotion, 2019). Unfortunately, chronic conditions are not treatable overnight, but they can often be im...
Preprint
With the recent evolution of mobile health technologies, health scientists are increasingly interested in developing just-in-time adaptive interventions (JITAIs), typically delivered via notification on mobile device and designed to help the user prevent negative health outcomes and promote the adoption and maintenance of healthy behaviors. A JITAI...
Article
Full-text available
Background: There is great interest in and excitement about the concept of personalized or precision medicine and, in particular, advancing this vision via various 'big data' efforts. While these methods are necessary, they are insufficient to achieve the full personalized medicine promise. A rigorous, complementary 'small data' paradigm that can...
Preprint
Advances in wearables and digital technology now make it possible to deliver behavioral mobile health interventions to individuals in their everyday life. The micro-randomized trial (MRT) is increasingly used to provide data to inform the construction of these interventions. This work is motivated by multiple MRTs that have been conducted or are cu...
Preprint
Full-text available
Mobile health (mHealth) interventions can enable new ways to improve health outcomes by intervening in the moment of need or in the right life circumstance. With recent advances in mobile computing and sensing techniques, mHealth interventions are now technologically feasible; current off-the-shelf mobile phones can acquire and process data in real...
Conference Paper
Self-tracking can help people understand their medical condition and the factors that influence their symptoms. However, it is unclear how tracking technologies should be tailored to help people cope with the progression of a degenerative disease. To understand how smartphone apps and other tracking technologies can support people in coping with an...
Article
Background: The US Preventive Services Task Force recommends out-of-office blood pressure (BPs) before making a new diagnosis of hypertension, using 24-h ambulatory (ABPM) or home BP monitoring (HBPM), however this is not common in routine clinical practice. Blood Pressure Checks and Diagnosing Hypertension (BP-CHECK) is a randomized controlled di...
Preprint
Mobile health is a rapidly developing field in which behavioral treatments are delivered to individuals via wearables or smartphones to facilitate health-related behavior change. Micro-randomized trials (MRT) are an experimental design for developing mobile health interventions. In an MRT the treatments are randomized numerous times for each indivi...
Article
There is a growing scientific interest in the use and development of just-in-time adaptive interventions in mobile health. These mobile interventions typically involve treatments, such as reminders, activity suggestions and motivational messages, delivered via notifications on a smartphone or a wearable to help users make healthy decisions in the m...
Preprint
Full-text available
There is a growing interest in leveraging the prevalence of mobile technology to improve health by delivering momentary, contextualized interventions to individuals' smartphones. A just-in-time adaptive intervention (JITAI) adjusts to an individual's changing state and/or context to provide the right treatment, at the right time, in the right place...
Preprint
In many mobile health interventions, treatments should only be delivered in a particular context, for example when a user is currently stressed, walking or sedentary. Even in an optimal context, concerns about user burden can restrict which treatments are sent. To diffuse the treatment delivery over times when a user is in a desired context, it is...
Article
Background HeartSteps is an mHealth intervention that encourages regular walking via activity suggestions tailored to the individuals’ current context. Purpose We conducted a micro-randomized trial (MRT) to evaluate the efficacy of HeartSteps’ activity suggestions to optimize the intervention. Methods We conducted a 6-week MRT with 44 adults. Con...
Article
Much of the recent research in mobile health (mHealth) has focused on the development of apps and wearables for promoting healthy behavior changes, such as losing weight, increasing physical activity, or adhering to a medication regimen. These interactive systems help users make changes in their behavior by, for instance, tracking healthrelated act...
Article
Background: Adaptive behavioral interventions are individualized interventions that vary support based on a person's evolving needs. Digital technologies enable these adaptive interventions to function at scale. Adaptive interventions show great promise for producing better results compared with static interventions related to health outcomes. Our...
Article
Full-text available
Background The science of implementation has offered little toward understanding how different implementation strategies work. To improve outcomes of implementation efforts, the field needs precise, testable theories that describe the causal pathways through which implementation strategies function. In this perspective piece, we describe a four-ste...
Article
Mobile Health (mHealth) interventions are a promising tool in providing digitally mediated integrative care. They can extend care outside of the clinic by providing reminders to take medications, assisting in managing symptoms, and supporting healthy behaviors including physical activity, healthy eating and stress management. mHealth interventions...
Article
Creating actionable plans has been shown to be helpful in promoting physical activity. However, little rèsearch has been done on how best to support the creation and execution of plans. In this paper, we interviewed 16 participants to study the role that context plays in the formulation and execution of plans for physical activity. Our findings hig...
Article
Background: Control systems engineering methods, particularly, system identification (system ID), offer an idiographic (i.e., person-specific) approach to develop dynamic models of physical activity (PA) that can be used to personalize interventions in a systematic, scalable way. The purpose of this work is to: 1) apply system ID to develop indivi...
Article
Full-text available
Background: Substance use is an alarming public health issue associated with significant morbidity and mortality. Adolescents and emerging adults are at particularly high risk because substance use typically initiates and peaks during this developmental period. Mobile health apps are a promising data collection and intervention delivery tool for s...
Article
Mobile Health (mHealth) interventions are behavioral interventions that are accessible to individuals in their daily lives via a mobile device. Most mHealth interventions consist of multiple intervention components. Some of the components are “pull” components, which require individuals to access the component on their mobile device at moments when...
Article
Contextual bandits have become popular as they offer a middle ground between very simple approaches based on multi-armed bandits and very complex approaches using the full power of reinforcement learning. They have demonstrated success in web applications and have a rich body of associated theoretical guarantees. Linear models are well understood t...
Conference Paper
Physical activity yields affective benefits like mood improvement and a sense of accomplishment or a general sense of feeling good. However, existing interventions to promote physical activity typically do not make tracking or visualization of affective benefits a prominent part of the interface. We conducted a survey asking people about physical a...
Conference Paper
Full-text available
Despite the recent progress in sensor technologies, many relevant health data can be only captured with manual input (e.g., food intake, stress appraisal, subjective emotion, substance use). A common problem of manual logging is that users often disengage within a short time because of high burden. In this work, we propose SARA, a novel app to enga...
Chapter
Micro-randomized trials (MRTs) offer promise for informing the development of effective mobile just-in-time adaptive interventions (JITAIs) intended to support individuals’ health behavior change, but both their novelty and the novelty of JITAIs introduces new problems in implementation. An understanding of the practical challenges unique to rollin...