Effectiveness of health education in the self-care and adherence of patients with heart failure: a meta-analysis

Objective: to evaluate in the literature the effectiveness of the health education interventions in self-care and adherence to treatment of patients with Chronic Heart Failure. Method: a systematic review with meta-analysis. Studies were selected that compared health education interventions with the usual care to assess the outcomes of adherence and self-care. The quality of the methodological evidence was assessed by the Grading of Recommendations, Assessment, Development and Evaluation system. Results: the educational interventions were more effective in relation to the usual care in the outcome of adherence (fixed effect=0-3841; p-value <0.001). There was no statistical difference in the outcome of self-care (fixed effect=0.0063; p-value=0.898). Conclusion: the educational interventions improved the outcome of adherence, though not self-care in the patient with Heart Failure.


Introduction
Heart Failure (HF) is a complex clinical syndrome, in which dyspnea, fatigue and fluid retention can limit tolerance to exercise and functional capacity (1) . Despite advances in pharmacological and non-pharmacological follow-up, HF affects thousands of people worldwide and is associated with frequent use of the health services (2) .
A number of studies point out that the prevalence of HF can affect nearly 1%-2% of the world population, with 6% to 10% of the individuals being over 65 years old (3)(4) . In Brazil, between June 2018 and June 2019, HF totaled 212,208 thousand cases of hospitalizations and 24,035 thousand deaths. These numbers point to HF as the leading cause of hospitalization for diseases of the circulatory system and the second leading cause of mortality in Brazil (5) .
Lack of adherence to the therapeutic regimen, especially with regard to lifestyle changes, is one of the factors that contribute for decompensation episodes and readmission due to HF (1,(6)(7) . However, one of the main reasons for lack of adherence is the low capacity of the individuals to exercise their self-care (8)(9) , which is understood as the natural decision-making process of individuals and their families, aimed at both the prevention and treatment of the disease (10)(11) .
In HF, the capacity for self-care can be limited by low health literacy, cognitive deficit, depressive symptoms, presence of multiple comorbidities and low self-efficacy to perform self-care (12)(13)(14) .
The low health literacy in patients with HF translates into less knowledge related to the disease, worse self-care behavior, low quality of life and decreased medication adherence prescribed in HF. It is also associated with the incidence of mortality in outpatients and inpatients.
In addition, it is emphasized that low health education can predict morbidity and mortality (15)(16) .
These factors directly affect patient adherence and interaction with health professionals, since it is a complex process that ranges from complying with and following the treatment prescribed in search for well-being and health, represented by changes in the lifestyle that include attending appointments and greater control of the medication (17) .
A number of studies indicate that, with an adequate guidance on the disease and patient involvement in selfcare, health outcomes improve (18)(19) . Patient education is a fundamental component of HF care management programs, in addition to optimizing clinical treatment and psychosocial support. This strategy reduces hospitalization due to HF and mortality in post-discharge patients (20) .

Method
This is a systematic review with meta-analysis, conducted according to the precepts of the Joanna Briggs Institute (JBI) -Evidence Synthesis Groups, in addition to the indications of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (21) .
The protocol entitled "The effectiveness of interventions in health education in the adherence to treatment and self-care of patients with heart failure: a systematic review" is published in the PROSPERO platform under number CRD42018094051.
The review had the following guiding question: What is the effectiveness of health education in the adherence to the treatment and self-care of patients with HF?
For the elaboration of the guiding question and search for articles, the PICO strategy was used, which is an acronym for Patient/Problem (heart failure), Intervention (health education), Control/Comparison and Outcomes (patient compliance, self-care) (22) . It should be noted that, in the PICO strategy of this study, the "C" was not inserted as a specific intervention, since any intervention deemed as control in the articles was considered for comparison analysis with health education interventions.
The following inclusion criteria were adopted: studies with adults over 18 years of age with HF, addressing a health education intervention for adherence to the treatment and/or self-care; indexed in databases  The descriptors selected were the following: heart failure/insuficiência cardíaca, health education/educação em saúde, patient compliance/cooperação do paciente, self-care/autocuidado, which were used for all search in the databases identically, using the Boolean operator "and" in the searches.
To achieve better results, the search was divided into two moments, one with the "patient compliance" descriptor and the other with the "self-care" descriptor.
This division occurred because, by inserting patient compliance or self-care, the search was nonspecific, that is, there were many studies that were not related to the study objective. In this sense, according to what is importance (or weight) for calculating the overall effect is different for each study. The weight size is influenced by the quality of the estimates presented by the study.
Two factors are decisive for calculating the weight, the variability found and the sample size used (25) .
The results of the meta-analysis were presented using the forest plot graph, where each study is shown with its respective effect size, 95% confidence interval, the weights for each model (fixed and random) and the estimate of the overall effect of the study (25) . In order to account for the effect size, the standardized mean difference was used for both scales. The results were obtained by using the meta package of the R software.

Results
The search resulted in 802 studies which, after applying the eligibility criteria, derived in 19 studies: 15 with self-care outcome, and five (5) with adherence outcome. The study inclusion process is described in Figure 1.
effect of the intervention. There is moderate (B) evidence when there is moderate confidence in the estimated effect. When confidence in the effect is limited, it is considered low (C) and, when any effect estimate is uncertain, there is a very low level (D) (24) .
The data were organized in charts and tables for the synthesis of information from the journals, such as: title, author's name, year of publication, in addition to the sample size, outcome result (mean) and standard deviation (or variance) of the control and intervention groups.
The means, standard deviation and sample size of the study were calculated. To calculate the effect size, the difference of means was performed, divided by the combined standard deviation, multiplied by a correction factor. To calculate the weights in each study, the inverse variance method was applied (25) .
The Fixed Effect and Random Effect models were used to represent the data and estimate the overall effect of the study. The fixed effect is a form of modeling that treats the selected studies as unique, thus the degree of  It should be noted that, in the studies analyzed, the control group was treated with usual care, which was described in the studies as routine outpatient follow-up pursuant to institutional protocols.

Study/ Country/ Year
Intervention/Professional Type of study Study 13 (38) Netherlands, 2014 Telemonitoring system (Health Buddy®) + Usual care. Nurse  Regarding the adherence outcome, the global effects obtained by applying the fixed and random effects models were 0.3841 and 0.7604, respectively. The models had convergent results. Both models were significant (fixed p-value <0.001 and random p-value 0.048). Therefore, on average, the results of adherence in the experimental group were higher than in the control group.

Study/ Country/ Year
Intervention/Professional Type of study  The interventions implemented in these studies were, for the most part, two combined strategies: home visit (HV) + Phone consultation (PC) or PC with application of an educational leaflet (39)(40)42,44) . There were also two individual strategies (personalized guidance based on the inferior vena cava ultrasound examination and educational group) (41,43) . Two studies (No. 14 and No. 19) that used HV + PC were the ones that came closest to the result in favor of the experimental group for the adherence outcome (39,44) . In Figure 4, the quality of evidence of the results assessed by the GRADE system was considered low for both outcomes, which suggests that confidence in the effect is limited. The risk of bias, inconsistency and imprecision were the main factors that determined the low quality of evidence in the studies assessed.  it was evidenced that those who used HV+PC were the ones that had better significant results in favor of the experimental group (39,44) .
Corroborating this finding, in an experimental study with 201 patients, telephone follow-up took place seven and 30 days after discharge. There was an improvement in the outcome of medication and non-medication adherence after 90 days in the intervention group in relation to the control group (p<0.001) (45) .
In a before-and-after experimental study conducted with patients hospitalized due to decompensated HF, in two reference institutions in Rio Grande do Sul, the intervention consisted of three home visits after hospital discharge, with an interval of 45 days. The outcome of adherence to the treatment was assessed using a validated questionnaire, in the first and third HVs. 32 patients were included, with a mean age of 65±16 years old. The adherence scores were 16±2.6 vs. 20.4±2.7 on the first and third visits (p=0.001). After the intervention, an increase in the score of adherence to the treatment of the patients with HF was evidenced, highlighting the improvement in questions related to daily weight verification and restriction of water intake (46) .
Personalized medicine is a current and extremely relevant approach, since it considers the particularities of each patient (47) . One of the studies included in this review used ultrasound images (USG) as an education strategy for patients with decompensated acute heart failure, relating the ultrasound image of their inferior vena cava (IVC) with its liquid state (congestion) (43) . Although this study did not show positive effects, another showed that an intervention that included educational materials based on images reduced hospitalization or death for a period of 12 months (48) .
It has been shown that the educational group is a beneficial strategy in adherence to the treatment.
A randomized clinical trial conducted in Brazil tested the effect of the guidance group on adherence to the treatment and self-care in patients with heart failure, showing an improvement from 13.9±3.6 to 14.8±2.3, from the initial to the final scores (14) . The authors concluded that, even with little difference in the initial and final scores, the adoption of an educational program is an important strategy in the health sector, especially in patients with chronic diseases (14) ; however, it cannot guarantee a change in behavior because the relationship between what people know and adopt as a life habit is a tenuous and individual thing, which can be affected by several variables.
With regard to self-care, the fixed effect was not significant; thus, the control and experimental groups produced similar results. It is observed that three papers concentrate almost 40% of the global fixed effect, since they are studies with a good sample size and little variability found (38)(39)(40) . Therefore, in the fixed-effect model, and Self-Care of Heart Failure Index (SCHFI) (49) . Other instruments are discussed in the literature, such as the Self-Care Behaviors Questionnaire (SCBQ) (50) and the Test of Functional Health Literacy in Adults (S-TOFHLA), which assesses the level of health literacy, with psychometric validation for Brazil (51)(52) .
Although the fixed effect did not show differences between the experimental and control groups, the studies that individually came closest to the result in favor of the experimental group were related to the electronic resource (31) and to the support group for patients and family members (37) .
The complexity of self-care in HF can pose threats to the proposal and adherence to treatments, especially in patients with low health literacy. This, in turn, is associated with the inability to process, understand and put into practice information about the disease, resulting in difficulties to understand and follow the guidelines for the proposed treatment, resulting in greater morbidity and mortality (53)(54) . Recent studies have already associated low HF literacy with a deficit in knowledge of the disease, low self-care, readmissions and mortality (54)(55) .
Socioeconomic, demographic and educational factors are determining factors in low health literacy.
Patients with these conditions generally have difficulty processing information about the treatment of the disease, such as reading notes and labels on medications, and understanding verbal information from their health professionals and educational materials (16) .  (1,20) .  (56) . The HV must be performed as soon as possible after discharge to reassess the clinical status and risk factors for readmission (56) .
Therefore, considering the findings of this study, the researchers recommend, as a priority, for better adherence to the treatment of HF patients, the adoption of combined HV+PC strategies.
The reality of the HF patients treated by the Unified Health System (Sistema Único de Saúde, SUS) denotes characteristics of high vulnerability for recurrent hospitalizations (57) . Considering this aspect, telephone consultations combined with home visits, implemented in family health modules and specialized clinics, promote the following benefits: reduced intervals between faceto-face consultations; increased bond and trust between patients, family members and health professionals; situational diagnosis of the patient and family and prevention of hospitalizations due to HF decompensation for preventable causes, decreasing hospitalization costs by the SUS (58) .
It is suggested that public institutions of basic/ specialized care add the HV+PC to their respective local care flows in referral and counter-referral systems in the access to patients with HF treated by the SUS.
In this meta-analysis, the method of assessing

Conclusion
Educational interventions improved the outcome of adherence, but not that of self-care in patients with HF.
More detailed analyses are necessary, with the association of other clinical outcomes in order to consolidate the effect of the educational interventions on this population.
It is suggested to include in future studies the outcome of health literacy to deepen the understanding and optimization of health education actions in HF.