Current measures of health and disease are often insensitive, episodic, and subjective. Further, these measures generally are not designed to provide meaningful feedback to individuals. The impact of high-resolution activity data collected from mobile phones is only beginning to be explored. Here we present data from mPower, a clinical observational study about Parkinson disease conducted purely through an iPhone app interface. The study interrogated aspects of this movement disorder through surveys and frequent sensor-based recordings from participants with and without Parkinson disease. Benefitting from large enrollment and repeated measurements on many individuals, these data may help establish baseline variability of real-world activity measurement collected via mobile phones, and ultimately may lead to quantification of the ebbs-and-flows of Parkinson symptoms. App source code for these data collection modules are available through an open source license for use in studies of other conditions. We hope that releasing data contributed by engaged research participants will seed a new community of analysts working collaboratively on understanding mobile health data to advance human health.

Digital technologies such as smartphones are transforming the way scientists conduct biomedical research. Several remotely conducted studies have recruited thousands of participants over a span of a few months allowing researchers to collect real-world data at scale and at a fraction of the cost of traditional research. Unfortunately, remote studies have been hampered by substantial participant attrition, calling into question the representativeness of the collected data including generalizability of outcomes. We report the findings regarding recruitment and retention from eight remote digital health studies conducted between 2014–2019 that provided individual-level study-app usage data from more than 100,000 participants completing nearly 3.5 million remote health evaluations over cumulative participation of 850,000 days. Median participant retention across eight studies varied widely from 2–26 days (median across all studies = 5.5 days). Survival analysis revealed several factors significantly associated with increase in participant retention time, including (i) referral by a clinician to the study (increase of 40 days in median retention time); (ii) compensation for participation (increase of 22 days, 1 study); (iii) having the clinical condition of interest in the study (increase of 7 days compared with controls); and (iv) older age (increase of 4 days). Additionally, four distinct patterns of daily app usage behavior were identified by unsupervised clustering, which were also associated with participant demographics. Most studies were not able to recruit a sample that was representative of the race/ethnicity or geographical diversity of the US. Together these findings can help inform recruitment and retention strategies to enable equitable participation of populations in future digital health research.

Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Most people with mental health disorders fail to receive timely access to adequate care. Digital technology has the potential to drive a sea change in the psychosocial treatment of mental health problems, especially in minority populations that have known barriers to accessing and utilizing traditional treatment approaches. Objective: The objective of the present study was to compare recruitment, engagement, and treatment outcomes between a sample of depressed Spanish-speaking Hispanic/Latino individuals compared to a cohort of depressed English speakers using 3 different self-guided mobile apps (iPST (based on evidence-based therapeutic principles from problem-solving therapy [PST]); Project: Evolution™ (EVO; a cognitive training app based on cognitive neuroscience principles); and Health Tips (health information app that served as an information control)). Methods: Participants were recruited for this randomized controlled trial using social media platforms, internet-based advertisements, and traditional fliers in select locations in each state across the United States. Assessment and self-guided treatment was conducted on each participant's smartphone or tablet. We enrolled 646 English-speaking and 437 Spanish-speaking adults (≥18 years old) with mild to moderate depression as determined by a 9-item Patient Health Questionnaire (PHQ-9) score ≥5 or an endorsement of impaired functioning. Outcomes were depressive symptom severity (measured using PHQ-9) and functional impairment (assessed with Sheehan Disability Scale). Engagement in the study was assessed based on the number of times participants completed active surveys. Results: We screened 4,502 participants and enrolled 1,083 participants from throughout the US over 6 months. The majority of the participants were recruited via posts on craigslist.org, with significant participant acquisition costs present when recruiting Spanish speakers ($31/ participant) compared to English speakers ($1.46/participant). Long-term engagement surfaced as a key issue with Spanish speaking participants, as these individuals dropped out two weeks earlier than their English counterparts. Furthermore, while no significant difference between Spanish- and English speakers were observed for treatment remission, Spanish-speakers consistently reported higher depression symptoms compared to their English speaking counterparts. Conclusions: Our findings suggest that fully remote mobile-based studies can attract a diverse participant pool including people from lower socioeconomic backgrounds (in this case Hispanic/Latinos). However, keeping participants engaged in this type of ‘low-touch’ research study remains challenging. Further research including user-centered approaches are needed to understand the culturally adequate incentive levels, notification strategies and effective mobile content formatting to enhance the recruitment and retention of minority populations. Clinical Trial: Clinicaltrials.gov Identifier: NCT01808976