In this research the investigators will develop and test an innovative scalable mobile health and digital cardiovascular monitoring system within a longitudinal deeply characterized cohort with three components: 1) smartphone application (app) designed to promote adherence, integrate digital and mHealth information, and facilitate communication with participants and researchers; 2) smartwatch activity monitoring using the Apple iWatch; and 3) home blood pressure (BP) monitoring using the Withings blood pressure device.

The objective of the messaging trial is to test the effect of messaging strategies on improving participants' long-term use of and engagement with our selected mobile health technologies and on increasing response rate of survey data collection.

The research design includes a cohort eFHS Study and an embedded randomized factorial trial on a subset of the cohort.

For the primary e-cohort, the investigators will build a custom mobile app for use within the Framingham Heart Study (FHS) to digitally collect data, compare it against research clinic-collected data, quantify risk factor burden, and perform CVD risk prediction. The app development will focus on 1) CVD risk factor data that would benefit from more frequent ascertainment than the every four to eight year FHS examination cycles; 2) circumstances where in vivo assessment may be superior to clinic-based assessment; 3) key endpoints of the FHS that are considered FHS landmarks. In addition to the eFHS App, participants will be offered wireless devices (Withings BP) to measure blood pressure and an Apple Watch to measure heart rate and steps per day.

For the messaging trial, the investigators will conduct a randomized factorial trial phase to test the effect of messaging strategies. Participants will be sent a weekly notification through the eFHS app. Participants will be randomly allocated to one of 8 groups defined according to the following: using personalized reminder messaging vs. standard neutral messaging; notification sent on a weekday vs. weekend; notification sent in the morning vs. the evening. The three main comparisons will be simultaneously evaluated according to a 2x2x2 factorial design.

Inclusion Criteria for the eFHS study:

• Participants of the FHS Third Generation, Omni Group 2, and New Offspring Spouse Cohorts attending the in-person examination 3 with access to a smartphone or home internet access and English speaking/reading.

Specifically for the RCT substudy (re: engagement with select mobile health technologies):

• English-speaking individual
• Owns an iPhone with compatible iOS (version 9 or higher);
• Residence in the United States
• Provision of permissions for notifications and data sharing with the Research Center
• Provision of signed and dated informed consent

Exclusion Criteria:

• Participants who do not meet the inclusion criteria

eFHS researchers, statistician, research assistant, and clinic staff are masked to intervention assignment.