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Effectiveness of “Internet+” Based Cardiac Rehabilitation on Prognosis of Patients with Coronary Heart Disease: A Meta-Analysis

Objective Meta-analysis was used to systematically evaluate the impact of Internet-based cardiac rehabilitation on the health of patients with coronary heart disease. Methods Randomized controlled trial study (RCTs) of the effects of Internet-based cardiac rehabilitation on cardiovascular risk factors, motor function and psychological status in patients with coronary heart disease has been systematically studied. Results A total of 13 articles were included. Meta-analysis showed that internet-based cardiac rehabilitation training could effectively reduce the total cholesterol level [MD = -0.15, 95% CI (-0.28, -0.02), P = 0.02] and triglyceride level [MD = -0.19, 95% CI (-0.32, -0.06), P = 0.01], increase the maximal oxygen uptake (VO2 max) [MD = 0.9995, CI (0.161.83) P = 0.02] and physical activity level [SMD = 0.51, 95% CI (0.07, 0.9), P = 0.02], and improve the self-efficacy [SMD = 0.50, 95% CI (0.17, 0.83), P = 0.01] and improved quality of life [SMD = 1.34, 95% CI (0.12, 2.56), P = 0.03] of patients. However, there was no significant improvement in blood pressure and body mass index, depression and anxiety. Conclusion Internet-based cardiac rehabilitation can significantly reduce cholesterol and triglyceride levels and improve theVO2 max, physical activity, self-efficacy and quality of life, but is not effective on the level of blood pressure, BMI, anxiety and depression. Due to the limitations of methodological quality and sample size of included studies, more studies with high-quality and large sample are needed to further evaluate its effectiveness.


Introduction
With the improvement of people's living standard and the change of diet structure, the incidence of coronary heart disease (CHD) increased year by year. The number of cardiovascular patients in China has exceeded 330 million, among which coronary heart disease has exceeded 11 million and is increasing by 20% every year [1]. At present, surgery and drug therapy cannot completely eliminate the risk factors of coronary heart disease, and patients still need to recover cardiopulmonary function through rehabilitation training [2,3]. Cardiac rehabilitation is a comprehensive intervention method, including guiding patients to take medicine regularly and exercise training and guiding their diet and health education, which is an important means to reduce the incidence and sudden death rate of patients with coronary heart disease and improve the quality of life of patients [4,5]. Although the model of cardiac rehabilitation has been established, due to the limitations of time and environment, the development of cardiac rehabilitation is not ideal, and patients' participation and exercise duration are low [4,6]. Internet + refers to the provision of medical information and services through communication technology, which has been widely used in many fields such as disease prevention, chronic disease self-management and health promotion [7]. Although there has a been meta-analysis of the effects of Internet+ based cardiac rehabilitation on CHD patients' health, this analysis did not include studies of China [8]. Therefore, this study aims to evaluate the impact of Internet + based cardiac rehabilitation on the health of patients with coronary heart disease through a systematic search of Chinese and English literatures and provide medical evidence for its promotion and application. (1) Study type: Randomized controlled trial (RCT); (2) Intervention population: Adults diagnosed with coronary heart disease (atherosclerosis, angina, myocardial infarction) or coronary revascularization; (3) Intervention methods: Routine nursing was carried out in the control group, and "Internet+" based cardiac rehabilitation or "Internet+" based cardiac rehabilitation based on control group was carried out in the experimental group. (4) Outcomes: Cardiovascular risk factors (blood pressure, body mass index (BMI), cholesterol), motor function indicators (V O2 Max, physical activity), and mental health indicators (quality of life, anxiety, depression, self-efficacy) 2.2.2. Literature Exclusion Criteria. (1) The articles with data that were not related to this study or cannot be converted to the required data; (2) Repeatedly published papers; (3) Lowquality literature; (4) Case report, Reviews, abstracts, conference papers; (5) Unable to get full text; (6) Incomplete data or data error; (7) Literature other than Chinese and English 2.3. Literature Screening and Data Extraction. Two researchers independently evaluated the included articles. The data of the included literature shall be extracted and resolved through negotiation when there is divergence. The data extracted included first author, characteristics of study subjects, sample size, intervention measures and outcome indicators. Finally, the formal data table (Table 1) was formed after discussion between the two people.

Literature Quality
Evaluation. The quality of the articles was assessed by two trained researchers using the bias assessment tool of Cochrane Handbook for Systematic Review of Interventions 5.1.0. The evaluated contents included random sequence generation, allocation concealment, blind method, description of lost follow-up, selective reporting of study results, and other sources of bias.
2.5. Statistical Analysis. Meta-analysis was performed on the data by Revman 5.3 software. Mean difference (MD) or standardized mean difference (SMD) were used as the effect indicator. Heterogeneity between studies was determined by Q test. When I 2 >50% and P ≤0.1, subgroup analysis or sensitivity analysis was used to determine the source of heterogeneity or only descriptive analysis was performed. If heterogeneity could not be eliminated, random effect model was used to combine effect size. When I 2 <50% and P >0.1, it can be regarded as no heterogeneity and fixed effect model was used for analysis.

Retrieved Results.
A total of 1,168 related articles were retrieved. Among them, 133 were in Chinese and 1,035 were in English. By Noteexpress software processing, 897 duplicate articles were deleted. After reading the titles and abstracts of the articles, 235 articles that did not meet the standards were included. After searching for the full text and reading the whole article, a total of 13 articles were finally included. Literature screening process is shown in Figure 1.The basic characteristics and quality evaluation of the included studies are shown in Table 1.
Seven articles [9,12,[17][18][19][20] reported the effect of "Internet +" based cardiac rehabilitation on triglyceride, with a total of 925 subjects included. The heterogeneity was small (P = 0.86, I 2 = 0%). The results of fixed-effect model showed that the decrease degree of triglyceride in the experimental group was significantly different from that in the control group [MD = -0.19, 95% CI (-0.32, -0.06), P = 0.005] (Figure 6). (Table 2). Four literatures [9,13,16,17] reported the effect of cardiac rehabilitation based on "Internet +" on maximal oxygen uptake in patients with coronary heart disease. The heterogeneity was small (P = 0.27, I 2 = 23%). The results of fixed-effect model showed that the improvement degree of maximal oxygen uptake in the experimental group was significantly different from that in the control group [MD = 0.99, 95% CI (0.16, 1.83) P =0.02].
Four literatures [11,14,17,19] reported the impact of "Internet +" based cardiac rehabilitation on quality of life of patients. The heterogeneity was large, so the random effect model was adopted. MacNew Scale [11,14], Dartmouth Quality of Life [17] and Chinese Cardiovascular Patients Quality of Life Assessment Questionnaire [19] were used to assess the quality of life in the four literatures. Due to the different scales of evaluation, the standardized mean was adopted, and the results showed statistically significant differences between the two groups [SMD = 1.34, 95% CI (0.12, 2.56), P = 0.03].
Three studies [11,14,18] reported the impact of "Internet +" based cardiac rehabilitation on self-efficacy of patients. General self-efficacy scale [11,14] self-designed questionnaire [18] were used for evaluation. The heterogeneity was small, so the fixed effect model was adopted. The results showed that there was significant difference between the two groups [SMD = 0.50, 95% CI (0.17, 0.83), P = 0.01].
Six articles [10-12, 14, 16, 19] reported the effects of Internet + based cardiac rehabilitation focus on depression. Hospital Anxiety and Depression Scale (HAD) [10,11,14,16], Patient Health Questionnaire-9 (PHQ-9) [12], Generalized Anxiety Disorder-7 scale (GAD-7) [12] and Somatization Symptom Self-Rating Scale [19] were used for evaluation. he results showed no statistically significant difference between the two groups. 258 Low-quality articles excluded.  Computational and Mathematical Methods in Medicine 3.3. Publication Bias and Sensitivity Analysis. Funnel diagram was plotted for the influence of Internet+ cardiac rehabilitation on diastolic blood pressure of patients with coronary heart disease, and the results showed that the two groups were symmetrical with no obvious publication bias, as shown in Figure 7. The fixed-effect model and random effect model were used to analyze each model, and the results of effect size were similar, indicating that the metaanalysis had stable and reliable quantitative combined results.

Effect Evaluation of Internet+ Based Cardiac
Rehabilitation. Maximal oxygen uptake and physical activity are important indexes to evaluate exercise tolerance of coronary heart disease. Many evidence-based medical evidences show that low level of exercise function is closely related to the risk of cardiovascular disease and all-cause mortality [22][23][24]. Prospective studies [25] also found that triglyceride levels were significantly positively correlated with the risk of  Figure 3: Influence of Internet+ based cardiac rehabilitation on diastolic blood pressure of patients with coronary heart disease. 5 Computational and Mathematical Methods in Medicine coronary heart disease. However, the lack of supervision of home cardiac rehabilitation often leads to insufficient exercise of patients, and the intervention effect cannot be guaranteed [5]. This study found that cardiac rehabilitation based on Internet + can increase activity tolerance and reduce total cholesterol and triglyceride levels of patients, and the results are similar to Su [8] and Rawstorn et al. [26] In the study of Rawstorn et al. [26], physical exercise level of patients undergoing home cardiac rehabilitation based on electronic technology was superior to patients receiving routine home rehabilitation or routine nursing, but there was no significant difference in aerobic exercise capacity between the two groups of patients in their study [26]. In the study, there was no significant difference in aerobic exercise capacity between the two groups, and the study combined two indicators of maximal oxygen uptake and metabolic equivalent, which showed large heterogeneity and may have some bias. In the present study, the reasons for the heterogeneity of physical activity may be related with the different subjects and measurement time, but the random effect model showed that the physical activity of the experimental group was improved compared with that of the control group. Cardiac rehabilitation training based on Internet + mode is more accessible, and continuous remote nursing monitoring is conducive to timely understanding of patients' lifestyle and providing professional support, enhancing exercise effects and promoting patients' recovery.
In addition, this study found that cardiac rehabilitation based on Internet + could enhance patients' self-efficacy and improve their quality of life. Su et al. [8] also reported in their meta-analysis that cardiac rehabilitation training can improve patients' quality of life. Some intervention studies [11,12,15] adopted the comprehensive cardiac rehabilitation model to emphasize the addition of lifestyle management on the basis of exercise and enhanced the support for cardiac rehabilitation of patients by combining team support and real-time supervision of online courses. At the same time, combined with theories such as planned behavior theory or cognitive behavior theory [4,11], positive feedback is provided to patients in the form of behavioral feedback and empowerment. These measures were likely to improve patients' sense of self-efficacy. The beneficial process or result of intervention further improved their quality of life. Therefore, it is expected to further strengthen the intervention effect to develop a comprehensive cardiac rehabilitation program based on exercise.
This study found that Internet + cardiac rehabilitation did not significantly improve patients' blood pressure, BMI, anxiety and depression and other indicators, which may be related to the different forms, frequency, duration and intensity of exercise. Besides, BMI, systolic blood pressure and other indicators have large individual differences, which are not sufficient for significant changes in a short term. More studies are needed in the future to evaluate the  Figure 6: Influence of Internet-based cardiac rehabilitation on triglyceride in patients with coronary heart disease. 6 Computational and Mathematical Methods in Medicine

Methodological Quality Evaluation of Included Studies.
Of the 13 included studies, 3 were of grade A quality, 10 were of grade B quality, and 10 described scientific randomization methods, indicating that the results were credible. In the included literature, only 6 studies implemented concealed grouping. Since the intervention process of Internet + cardiac rehabilitation requires the cooperation of patients and the guidance of experimenters, it is difficult to blind the interveners. Therefore, implementation bias was inevitable. However, blind method was applied to outcome measurement in some studies, and most outcome indicators were objective measurement indicators, thus avoiding measurement bias to a certain extent. All included literatures explained the situation of loss of follow-up and withdrawal, with good data integrity.

Limitations.
Heterogeneity existed in the study sample and methodology, such as different forms, frequency and duration of intervention of cardiac rehabilitation. Individual patient differences and limited feasibility of blind implementation were also part of the factors leading to heterogeneity. This paper focuses on the effect of Internet + cardiac rehabilitation on patients with coronary heart disease. Although there was high heterogeneity among some results of the study, it also revealed the necessity of this study from the side. In this study, only Chinese and English literatures were included, and literatures in other languages were not searched, which may lead language bias.

Summary
Compared with conventional rehabilitation, Internet + cardiac rehabilitation can effectively improve exercise tolerance, reduce blood lipid levels and improve the quality of life of patients with coronary heart disease, but the effect on blood pressure, BMI and other cardiovascular factors is not clear. Due to the limitations of the number and quality of the included studies, more high-quality studies are needed to validate it.

Data Availability
The labeled dataset used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest
The author declares no competing interests.

Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.