In this study, we compared the effectiveness of real-time remote CR with that of hospital-based CR for improving physical function, subjective satisfaction, and objective performance (i.e., activity limitations and participation restrictions). The physical functioning of remote CR patients significantly improved compared with that of hospital-based CR patients.
Data obtained from several studies of home-based CR suggest that it yields results comparable to those of hospital-based programs [6, 23].
Research on remote-based CR has focused on non-supervised types [6, 23], and there are few studies on real-time monitoring types [9]. Furthermore, there is no established system to detect adverse events (e.g., arrhythmias, chest symptoms). There are also challenges in terms of cost-effectiveness and other factors. According to Ralph et al., real-time remote CR is an effective and cost-effective treatment modality [12]. Remote CR, including the unmonitored type, showed no significant difference in total mortality and exercise capacity [10]. However, these previous studies were reported before the COVID-19 pandemic. Therefore, the physical functions as well as subjective satisfaction and objective performance reported in these studies could be different.
COVID-19 risk, close contact, and infection anxiety were all associated with the use of public transportation [24]. Therefore, these quality-of-life domains may be adversely affected during the COVID-19 pandemic, during which this study was performed.
COVID-19 is caused by the severe acute respiratory syndrome coronavirus 2, which is easily transmitted through the eyes, tongue, and nasal passages [25].
Patients with cardiovascular disease are at risk of severe disease if they contract COVID-19 [26, 27]. There was a high degree of constraint in terms of outdoor activity among older adults during this period because of the fear of infection. Even in our cohort, five patients (25%) in the hospital-based CR group were excluded because they refrained from going out owing to concerns about infection.
Two participants in the remote CR group were excluded as one of them required treatment for atrial fibrillation and another patient experienced digestive disease. Therefore, we ascribed from these results that remote CR could eliminate the concerns regarding infectious diseases. No adverse events were observed during the study. In remote CR, real-time management of ECG and blood pressure measurements during exercise are pertinent challenges [28]. The remote ECG management device used in this study can collectively manage ECG and oxygen saturation using the Borg scale in real time. Therefore, it is useful for the early detection of physical abnormalities in patients with CVD.
Many studies have been conducted to evaluate the improvements in physical function due to CR. Restrictions on outings due to the COVID-19 pandemic in Japan have increased the risk of frailty and resulted in weight gain in convalescent CR patients [29]. This study showed a significant improvement in the remote CR group. This may be attributed to the continuation of stable exercise therapy in the home environment even during the COVID-19 pandemic. Educational guidance in this study includes not only dietary guidance but also exercise guidance in the home environment. We believe that these in-home exercise instructions can be performed in a manner similar to remote CR, resulting in greater improvement.
Improving quality of life is important for CR, and during the COVID-19 pandemic, health literacy and health-related quality of life have declined [30].
WHODAS2.0-J is currently the only measure based on the International Classification of Functioning, Disability and Health biopsychosocial model [22]. While WHODAS2.0-J asks what a person “does” in a particular domain, WHOQOL-BREF asks what the person “feels” in that domain. However, there are no reports of remote-based CR using WHODAS2.0-J and WHOQOL-BREF.
Therefore, we used the WHOQOL-BREF and WHODAS2.0-J questionnaires for a comprehensive assessment of quality of life. The ΔWHOQOL-BREF scores did not differ between the remote and hospital-based CR groups. Moreover, ΔWHODAS2.0-J scores also did not significantly differ between the groups.
Real-time remote CR revealed significantly improved participation based on WHODAS2.0-J scores. The patients were asked how their situation and the people around them made it difficult for them to participant in social activities; it also included questions about the impact of health condition on quality of life.
With regards to participation, remote CR was more effective than hospital-based CR. Further, we can conclude that remote CR is equivalent to hospital-based CR in terms of performance in the other domains, including cognition, mobility, self-care, social interaction, and life activities.
In addition, objective performance was significantly improved with remote CR. Remote CR is an effective treatment modality to improve the quality of life. We examined the patients in terms of their social interaction levels using the WHODAS2.0-J assessment, which was concluded to be a significant contributor to Δpeak VO2 in remote CR.
The patients in the remote CR group contributed significantly to getting along with other people. In addition, mobility (WHODAS2.0-J assessment) was a major contributor to Δpeak VO2 in hospital-based CR. In remote CR, it is important to assess not only physical function but also objective performance and subjective satisfaction.
Study limitations
Since the study was conducted during the COVID-19 pandemic, the number of participants was very limited. Patients eligible for hospital-based CR and those who lived alone or had severe CVD were excluded. This study was designed as a quasi-randomized controlled trial for safety reasons. Since no adverse events were observed in this study, there is a need to conduct this study as a randomized controlled trial. Furthermore, it was a single-center study; a multi-center collaborative study should be considered in the future. In addition, the Quasi-randomization-controlled trial setting limits the potential generalization of the findings. In the future, the efficacy of remote CR in severely ill patients and patients living alone will require more comprehensive research. Further risk stratification according to illness severity will also be required in future studies.