This study demonstrated that unsupervised HBPR in outpatient clinics can improve clinical outcomes in patients with COPD, thereby suggesting that PR can be recommended even when regular hospital visits are difficult. After 8 weeks of unsupervised HBPR, patients in the compliant group showed favorable outcomes; the CAT score, BODE index, and FEV1 were improved significantly. To our knowledge, this is the first study to suggest the benefits of unsupervised HBPR in compliant patients.
The CAT and mMRC scores were improved significantly compared with those at baseline in the compliant group. Considering that a score of ≥ 2 in CAT was regarded as a significant change, the change of − 4.61 in the present study indicated clinically meaningful improvement. The BODE index, one of the secondary outcomes in this study, is a well-known prognostic index for patients with COPD.[25, 28] The compliant group showed a marginal significant improvement in the BODE index (from 4.04 to 3.04; P = 0.07), which suggests that this type of unsupervised HBPR improves prognosis, although further study with more patients is necessary.
PR is considered as one of the highly effective treatment interventions for patients with COPD, with reports stating that PR alleviates dyspnea and fatigue and improves physical and emotional functions. In particular, improved physical function is directly associated with improved prognosis in patients with COPD. However, in real-world practice, PR is underperformed among these patients.[30, 31] The standard PR protocol requires multiple visits, high medical costs, and specialists from various fields. In addition, adherence to prescribed PR remains relatively low. Therefore, a large proportion of patients with COPD do not sufficiently benefit from an adequate prescription for PR. To overcome this issue, HBPR may be applied, which is considered as an alternative for standard PR. Nevertheless, the majority of studies on HBPR have included specialist supervision for PR,[16–20] which may be another hurdle as it increases medical costs and the requirement of resources. In those studies, specialists periodically visited patients and reeducated them about inhaler use and training methods, supervised the exercise sessions, and encouraged the patients using HBPR. Low socioeconomic status and transport-related inconveniences have been reported to be other reasons for the low adherence to PR.[32–34] From this perspective, the present study was meaningful as it demonstrated that unsupervised HBPR with one session can still have beneficial effects in patients with COPD. This study will be the basis for a better treatment strategy for patients with COPD who have difficulty in frequent hospital visits.
Horton et al. compared the effects of unsupervised HBPR with those of center-based PR. They found that HBPR failed to show noninferiority in most of the outcomes because several participants in the HBPR group did not complete the PR programs. Therefore, we hypothesized that compliance is the key factor in the success of HBPR. In the present study, the compliant patients were compared with the noncompliant patients. The results clearly demonstrated that the benefit of PR was noted only in the compliant group and that even one-time intervention could benefit the patients if they followed the training provided to them. Therefore, compliance, motivation, and appropriate education may be more important than where or how frequently these patients receive PR. Furthermore, the majority of participants preferred HBPR.[21, 35] In this context, the critical measure is educating patients about performing PR outside of hospital.
There are several limitations in this study. First, few outcomes showed no significant differences between the two groups and between pre- and post-HBPR in the compliant group, although all outcomes demonstrated trends of improvement. This could be due to the inclusion of a relatively small number of patients in this study, which might have been insufficient to show significance. Therefore, studies with larger sample sizes will be needed to confirm this aspect. Second, the efficacy of education on unsupervised HBPR at 8-week intervals was compared with noncompliance. We did not compare the education at 8-week intervals with standard PR. In addition, we observed the participants for only 8 weeks. Therefore, further study would be required to validate the noninferiority and the long-term effects of patient education at 8-week intervals for unsupervised HBPR.
Despite these limitations, this study has indicated the importance of clinicians’ efforts to promote PR in patients with COPD. These efforts can lead to improved symptoms and quality of life in compliant patients. Education about unsupervised HBPR can be performed even when there is a lack of medical resources. Although a randomized controlled study with a large number of patients would be ideal, the present study demonstrates unsupervised HBPR as a possibility when it is not easy to prescribe standard PR for patients with COPD. Because only approximately 60% of patients adhered to unsupervised HBPR, further study on the strategy to increase compliance is necessary to benefit more patients with COPD.