Medical image information is divided into two groups: images that conform to the Digital Imaging and Communications in Medicine (DICOM) standards and medical images such as pathological slides, endoscopic images, and retinographic images.”

Until recently, digital healthcare was employed as a major method for monitoring patients and for the integration, analysis, and prediction of information. However, digital healthcare has recently been extended to areas of treatment based on powerful mobile devices with analytical capabilities.

Pear Therapeutics, a start-up in the United States, is taking the lead in digital therapeutics. The application “reSET,” developed by the company, was licensed by the FDA in September 2017 making it the first digital therapeutic application [14]. The reSET application is typically used for 90 days with a doctor’s prescription to treat various addictions and dependencies. The reSET-O application, licensed in 2018, is specialized for drug addiction and provides programmed treatment for 84 days. The reSET application assists users with cognitive behavioral therapy: the patients can train themselves to identify triggers linked to addictive substance use by self-monitoring their impulses or changes in thinking. The effect of reSET software on users was proved through randomized controlled trials (RCT) in combination with conventional off-line treatments. Advancing rapidly, Pear Therapeutics developed Somryst, an application for chronic insomnia licensed by the FDA. In July 2020, when corona-virus disease 2019 (COVID-19) was rampant, the company initiated a large-scale clinical study with real patients [15]. As a market leader, Pear Therapeutics is extending its business areas to schizophrenia, epilepsy, and post-traumatic stress disorder [16].

Omada Health provides a software program to prevent and manage diabetes, a widespread problem in the United States, focusing on preventing prediabetic patients from progressing to diabetes and helping them lose weight. The software drew much attention because it was applied in the Diabetes Prevention Program (DPP) promoted by the US Government [17]. Users of the online DPP provided by Omada Health showed a higher program completion rate and more weight loss than users of another DPP based on face-to-face consultation [18]. A 3-year longitudinal study showed that the group of subjects who had successfully completed the program maintained their reduced weight and low glycated hemoglobin levels in the long term [19].

Dexcom is a company that produces a continuous glucose monitoring system (CGMS), which is designed to measure and transmit real-time sugar levels through a device attached to the abdomen, not by blood sampling with a needle or lancet [20]. Remote patient monitoring through such a device facilitates intensive monitoring at home, similar to that in hospitals. However, intensive remote monitoring requires suitable sensors, a mobile system for collecting and transmitting data, an advanced Electronic Health Record (EHR) system for integrating the received data into the existing system, and a service provision system to provide appropriate monitoring and intervention [21].

Teladoc is the oldest and largest telemedicine company in the United States [22]. The average time that patients wait to be connected with a doctor after requesting a consultation is less than 10 minutes [23], and the degree of satisfaction of patients is over 90% [24]. Studies on remote patient monitoring are increasing worldwide, and the devices used for services, diseases, and patient groups subject to these services are also increasing rapidly. Several studies have highlighted the advantages of remote monitoring; however, extensive changes are necessary in the monitoring methods for full-scale implementation of services [25].

The classic wearable device measures physical activity levels. The first commercial wearable activity monitor was known as Fitbit. Subsequently, the activity tracking function was mounted on most wearable devices, such as the Apple Watch and Galaxy Watch, as a basic function. Wearable electrocardiogram (ECG) devices are represented by mobile measurement devices produced by Alivcor. This device measures the ECG when the user holds it with both hands, Additionally, it can analyze the ECG through a smartphone connected via Bluetooth and provide medical recommendations based on data analysis. The initial ECG measurement model received a license from the FDA as early as 2014 for the diagnosis of atrial fibrillation [26]. The Apple Watch received a medical device license from the FDA in 2018 for the ECG measurement function using the stem of the watch [27].

In addition to these examples, a wide variety of sensor services are being released into the mainstream healthcare sector to measure and manage body temperature, sleep, heart rate variability, blood sugar level, oxygen saturation, blood flow, electrical skin stimulation, and anatomical positions. Although, at present, the demand for wearable devices seems low, such devices are expected to play a vital role in healthcare services through detailed service design and technological development.

Genetic information is distinct from other types of digital healthcare information, holding the largest volume of data per case, and the highest potential for growth among digital healthcare services. Whole-genome testing, conducted in laboratories for patients with rare diseases, is raising a massive wave in healthcare services. Although the utilization of genome information is not entirely included in digital healthcare, a DTC service that enables patients to see varied results from genome analysis is considered an area of digital healthcare.

Since its establishment in 2006, 23andMe has provided DTC-type services. Starting in 2013, DTC services with regard to disease incidence risk or sensitivity to drugs were discontinued. In 2017, the FDA licensed the DTC service for the risk analysis of 10 diseases, including Parkinson’s and Alzheimer’s disease. In 2018, the FDA licensed the services for BRCA1 and BRCA2 genes, which are related to the onset of breast cancer [28].

Another establishment, Pathway Genomics provides both hospital-based services and DTC services. These services provided by Pathway Genomics, distinct from 23andMe, are focused on diet and exercise, helping customers customize their health management through genome analysis. Pathway Genomics focuses on health rather than disease.

Digital health safety includes issues related to improvements or threats to patient safety associated with the use of digital healthcare services, including digital healthcare errors, adverse events, and privacy.

Digital health quality includes the quality of healthcare services associated with the use of digital healthcare services. This category includes the technical aspects of digital healthcare, as well as the improvement of the medical process to improve quality.

Digital health efficacy refers to the improvement of health status indicators related to digital healthcare services, aimed at the measurement of clinical items for monitoring the effectiveness of digital healthcare, including guidelines for clinicians based on the results.

Digital health end-user experience deals with the experiences of end-users using digital healthcare technology or services. Digital healthcare end-users include patients, consumers, digital healthcare service developers, and policymakers.

This category describes various items that require investment to achieve the best results from digital healthcare, focusing on the relationship between resource inputs, such as labor, capital, and equipment, and the final health state evaluation. This category describes various methods to increase the efficiency of digital healthcare services, reduce unnecessary expenses, and improve productivity.

This category relates to the use of digital healthcare services for purposes that are beneficial to health management in local communities. The goal is to improve health management for particular disease groups or local communities with large populations. The benefits in this category may be evaluated in terms of various measures, such as increased life expectancy and improved emergency systems.

This category is related to healthcare equity, which means that everyone should have a fair opportunity, without unfair or remediable differences, in the distribution of healthcare services; All individuals must be at an equal advantage to access digital healthcare services.

Implementing digital healthcare services is not an easy feat for primary care physicians. A digital health coordinating center (DHCC) is needed as a local hub to support digital healthcare services provided by primary care physicians [30–32].

When a physician prescribes digital healthcare or digital therapeutics at a clinic, the DHCC can educate the patient about the correct way of using digital healthcare services as well as taking relevant precautions. Users are known to visit the DHCC only at the first use or at the first session, visiting the primary clinics at other times. The patient data extracted and saved through the digital healthcare services are transmitted to not only patients but also the DHCC, where medical staff (or coordinators) can monitor the measured data and provide feedback to patients or transmit summaries regarding conditions of individual patients to their primary care physicians. This allows primary care physicians to concentrate on examining patients in their clinics, and use the summaries of various measured data obtained from the hospitals and transmitted by the DHCC. This facility can reduce the burden on primary care physicians in terms of time, cost, and labor, and strengthen the expertise of DHCC.

Currently, since digital healthcare services are provided free of cost, the burden on medical staff and consumers is increasing. In medical centers, the initial training for digital healthcare users requires a considerable amount of time [33]. Nevertheless, owing to insufficient incentives, digital healthcare has not been activated. It is necessary to provide medical staff with incentives for digital healthcare to uplift the main areas of medical services. In addition, it is necessary to reorganize the laws on information protection and responsibility.