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Smartphone-based study of CV health feasible
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Conducting a CV health study exclusively through a smartphone-based app appears to be feasible, according to findings published in JAMA Cardiology.
The researchers launched the MyHeart Counts app, available to anyone in the United States, in March 2015 to conduct the MyHeart Counts Cardiovascular Health Study.
For the study, participants recorded their physical activity, filled out health questionnaires and performed a 6-minute walk test.
For the current paper, Michael V. McConnell, MD, MSEE, from the division of cardiovascular medicine at Stanford University and Verily Life Sciences LLC, and colleagues analyzed whether obtaining consent and collecting data entirely on a smartphone and using machine learning to cluster participants were feasible, and they examined associations between activity patterns, life satisfaction and self-reported disease.
Between March and October 2015, consent was obtained from 48,968 participants from all 50 states and the District of Columbia (median age, 36 years; interquartile range, 27-50; 82% men).
Participation data
Among all participants who consented, 81.7% uploaded data, 41.5% completed 4 of the 7 days of motion data collection and 9.3% completed all 7 days. In addition, 81.7% completed at least some part of the questionnaires and 10.2% completed the 6-minute walk test, which was made available at the end of 7 days.
The Heart Age Questionnaire also was made available after 7 days for those aged 40 to 79 years (43.1% of participants); 2.7% of consenting participants filled out all the fields needed for computation of heart age and 10-year risk score, the researchers wrote.
The app detected physical activity for 14.5% (standard deviation, 8%) of participants’ total recorded time, according to the researchers.
Significant predictors of life satisfaction were fruit consumption, sugary drink intake, recorded activity and self-reported vigorous activity, the researchers wrote.
Significant predictors of self-reported disease were family history, whole grain consumption and job activity, they wrote.
Life satisfaction was highest in the West and lowest in the Northeast; those in the West had an average of 1 hour more of physical activity per week than those in the Northeast.
Clusters of activity levels correlated with self-reported CV health status, and those in the least active cluster had elevated risk for chest pain, type 2 diabetes, heart disease and joint pain, according to the researchers.
Participants’ perception of activity bore little resemblance to sensor-estimated activity, and their perception of risk bore little resemblance to calculated CV risk, they wrote.
“Improvements in participant diversity and engagement will maximize yield from consented participants,” McConnell and colleagues wrote. “Large-scale, real-world assessment of physical activity, fitness and sleep using mobile devices may be a useful addition to future population health studies.”
Uncharted territory
In an invited commentary, Bonnie Spring, PhD, and colleagues wrote that a limitation is that physical inactivity is assumed when smartphone motion is not detected, but this “rests on the assumption that people carry their devices most of the time, a presumption that is untrue for many.”
However, Spring, from the division of behavioral medicine of the department of preventive medicine at Northwestern University Feinberg School of Medicine, and colleagues wrote that increasing use of accelerometers may help overcome that limitation.
“When accessed comprehensively, the dense continuous data transmitted by smartphones and wearable sensors create capabilities for health promotion intervention that have never previously existed,” she wrote. – by Erik Swain
Disclosure: The division of cardiovascular medicine at Stanford University received software development support from Apple. McConnell reports being employed by Verily Life Sciences. Please see the full study for a list of the other researchers’ relevant financial disclosures.
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