The World Health Organization estimated that about 17 million people died from cardiovascular problems worldwide in 2016.1) Cardiovascular diseases have the highest mortality rate in the world and, in Korea, with 119.6 cardiovascular-related deaths per 100,000, these diseases had the second-highest mortality rate after cancer.2) To prevent cardiovascular and cerebrovascular diseases, it is important to prevent their risk factors and help people to maintain healthy lifestyle behaviors through lifestyle management.3) Recent innovations in information and communication technologies and their diverse applications in medicine have created a new phenomenon in which patients voluntarily and independently try to maintain healthy lifestyles.4) In particular, vast amounts of personal health data are accumulating through people's uses of various biometric readers and sensors (that are wearable devices) linked to smartphones.5)6) Customized healthcare services for individuals that use these data are increasing and many platforms are being developed and researched regarding integrating and analyzing the data.7)8) In other words, a diversity of ways for patients to change their behaviors to achieve/maintain good health and prevent diseases are emerging. This development has important implications because diverse health information is being exchanged between patients and their healthcare providers in the process.9)

Ultimately, it would be foolish to ignore the vast amount of data being collected from patients. Currently, big data is the most important issue in medicine. The definition of “big data” is “intelligence assets that feature bulk storage, fast formation speeds, and diversity that mandate specific technologies and analysis methods to convert them into value.”10) In medicine, the term “Real World Data (RWD)” is a more common concept than “big data.”11)12) The United States Food and Drug Administration defines RWD as data used to make decisions about monitoring and reducing safety hazards and side effects or to develop tools for decision-making and practical guidelines for clinical practices.13)

Korea mainly uses 4 types of health-related RWD: 1) claim data provided by the National Health Insurance Corporation and the Health Insurance Review and Assessment Service, 2) electronic medical record data generated at hospitals, 3) genomic data, and 4) patientgenerated health data (PGHD) based on lifelogs. PGHD are compiled and measured by individuals using tools and devices at home, such as blood pressure monitors, blood sugar testers, pedometers, and so on.14)15) PGHD might be the most important new phenomenon in healthcare considering the changes occurring in medicine in the current fourth industrial revolution, which are reflected in digital healthcare and the emergence of telemedicine and telehealth. Data generation and measurement are essential to achieving customized healthcare using PGHD, and organic harmony among services to correctly apply analyzed data through data integration is needed to successfully manage patients.

PGHD can be collected by smartphones linked to wearable devices. PGHD collected this way are generated outside the hospital/clinical setting and must be verified a variety of different sample or populations of people. Some studies have used new methods to measure the diverse PGHD and confirm their practicality. Most clinical studies on digital healthcare via smartphone applications is related to PGHD.16)17) Table 1 lists 9 studies about data generation and monitoring via PGHD for diagnosing, preventing, and managing cardiovascular and cerebrovascular disease.18-26)

Using smartphones and wearable devices to influence cardiovascular and cerebrovascular health developed from the study of the feasibility of their efficacy in the clinical environment.27)28) Several studies have found positive influences of data obtained this way for cardiovascular and cerebrovascular health in improved everyday behaviors and self-care regarding the disease.16)17) The approach was found to be an effective way to lower healthcare costs because consistent patient care, even remotely applied, was possible.29) PGHD have received more attention than other types of patient data because they are accumulated outside hospitals, where patients spend most of their time. Just counting the number of steps walked outside the hospital setting, which is the simplest PGHD, was verified as clinically useful.30) Wearable devices that measure health status, such as electrocardiographs, heartrate monitors, thermometers, partial electromyography, and perspiration pH are under development.31-35) Studies on the uses of these devices suggest clinical practicality of PGHD for preventing cardiovascular and cerebrovascular disease and for cardiac rehabilitation.

However, although some devices, such as smart watches and smart shirts, demonstrated potential for generating and measuring data, most wearable devices are not easy to use and they are inconvenient, and, thus, their clinical effectiveness is difficult to verify. In Korea's current legal and clinical contexts, it is too early to implement patient services that include feedback based on PGHD collected by healthcare providers.

Platforms are needed to merge data for analytical purposes, and studies on a variety of platforms have been conducted regarding aspects of health other than cardiovascular and cerebrovascular diseases. The integrated platform named Beiwe includes a research portal, mobile application, database, data modeling, and analytical tools to identify symptoms and signs of disease at home and to instantly quantify the data.36) Platforms must be as simple as possible and easy to intuitively operate. In Korea, a design study was conducted on the Heartbeat integrated mobile platform, which supports patients' physical exercise, management of hypertension or diabetes medications, management of blood pressure/blood sugar, and smoking cessation, all aimed at preventing cardiovascular and cerebrovascular diseases.37) Additional studies are needed to verify the applicability and efficacy of these platforms for preventing and managing cardiovascular and cerebrovascular diseases.

An important characteristic of PGHD is that it consistently measures patients' present conditions, meaning that this approach monitors patients in real time. It would be even better to add direct monitoring and feedback from healthcare professionals to this function, but, with the current technology, that is an unrealistic goal. However, as diverse high-quality data accumulate and methodological analytical methods continue to improve, data-focused feedback is likely to become a patient service.

This paper describes the recent research trends in data generation, integration, and application for preventing and treating cardiovascular and cerebrovascular diseases using PGHD. Traditional healthcare services are expected to continue for the short term in Korea because of technological limitations in healthcare professionals' abilities to provide active feedback. However, ultimately, the most important factor to interpreting PGHD is whether the data yield medically valid and practical results. Mobile technologies, such as smartphone apps, are being emphasized as viable tools for preventing cardiovascular and cerebrovascular diseases, but we have verified their potentials and effects only in controlled environments. To obtain useful results for feasible clinical applications, we need to move beyond data collection. Medical concept applications are essential to developing PGHD into practical knowledge. Healthcare professionals must maintain their interest and focus on this matter.