• • To derive the provisional definition of health literacy for patients with cardiovascular disease by identifying the antecedents, consequences, dimensions, and attributes of health literacy for patients with cardiovascular disease through a systematic review of the literature;

• • To identify the dimensions, attributes, and indicators of health literacy for patients with cardiovascular disease through field research; and

• • To present the dimensions, attributes and indicators of health literacy for patients with cardiovascular disease that can be used in nursing practice and research, based on the attributes of health literacy for patients with cardiovascular disease derived from the theoretical analysis and field research.

1) Theoretical stage

In the theoretical stage of the hybrid model, the dictionary definitions and related literature are examined to investigate the definitions, attributes and essential meanings of a concept. Based on the results, the operational definition of the concept is derived by comparing and analyzing the identified attributes and definitions of the concept [19]. In this study, we examined the dictionary definitions and domestic and foreign academical papers to investigate the essential meanings of health literacy with the aim of identifying the conceptual definitions and attributes of health literacy for patients with cardiovascular disease.

In this study, we conducted literature search of foreign papers published between 2008 and 2018 through the CINAHL (Cumulative Index to Nursing & Allied Health Literature), PubMed, and EMBASE databases. We used search queries such as ‘health literacy or/and cardiovascular disease’ and ‘health literacy or/and coronary artery disease’ as the major search terms and additionally searched papers containing terms such as myocardial infarction, angina pectoris, and heart failure among. As for Korean papers, we searched research papers whose title, keywords, or body contained terms such as cardiovascular disease, myocardial infarction, angina pectoris, coronary artery disease, heart failure, and health literacy or one of the Korean translations for health literacy among the papers published during the decade from 2008 to 2018 through the database of the Korea Education & Research Information Service (www.riss4u.net). Of the 476 retrieved domestic and foreign papers, 69 papers, including duplicates, were initially extracted through the first data extraction process. Then, papers that contained the concept of health literacy were selected by examining the abstracts of the initially extracted studies. Afterwards, studies without the definition of health literacy or those which performed only the assessment of health literacy were excluded. As a result, 26 studies (6 domestic and 20 foreign studies) were finally selected, excluding 43 papers that did not deal with both cardiovascular disease and health literacy. Through the analysis of the finally selected studies, the definitions and attributes of the concept of health literacy for patients with cardiovascular disease were extracted and provisional definitions were constructed (Table 1).

Table 1 Components of Health Literacy of Patients with Cardiovascular Disease in Theoretical Stage Click for larger image

2) Fieldwork stage

In the field work stage of the hybrid model, by analyzing the data collected in the field research, the attributes of the concept identified through the analysis results of the theoretical stage are verified and the newly discovered attributes are identified [19]. In this study, a total of 13 participants were selected by convenience sampling among patients aged 30 or older who were diagnosed with myocardial infarction, angina pectoris, heart failure, or arrhythmia and were admitted to hospital or were receiving outpatient treatment in the outpatient care unit of the Division of Cardiology, Department of Internal Medicine at K University Hospital in S city. The attributes and concepts of health literacy for patients with cardiovascular disease were derived, and they were verified through interviews with the participants. The specific inclusion criteria for the participants were as follows: Adults aged 30 years or older; diagnosed with coronary artery disease, heart failure, arrhythmia, or valvular heart disease; able to read and understand the contents of the questionnaire written in Korean; have no difficulty in communicating with others; understand the study purpose, agree to participate in the study, and sign the informed consent form. The exclusion criteria were as follows: Individuals diagnosed with organic brain disease or mental illness or individuals who do not agree to participate in the study.

This study was conducted after receiving approval from the IRB of the university to which the researcher belonged (IRB No.: HYU-2019-02-013). The interviews with participants were conducted from January to April 2019, and they were performed 1 and 2 times per participant, 40 minutes to 1 hour per session. The investigator personally performed in-depth interviews, and they were conducted after obtaining informed consent from participants and explaining to them that they could withdraw from the research at any time if they wanted to. The interviews were carried out using the open-ended questions created after deriving a tentative definition of the concept of health literacy through the theoretical stage. All the contents of the interviews were recorded with the consent of the participants, and their non-verbal expressions were also recorded using field notes.

The major open-ended questions used were as follows: 'How did you normally manage your health?'. 'How much and what do you know about your cardiovascular disease?', 'Where do you usually get information about cardiovascular disease?', 'What kind of difficulty did you have using information about cardiovascular disease?', 'How did you use this information to actually manage your health?', 'What kind of difficulty did you have using medical institutions?', 'What kind of difficulty did you have communicating with your doctor or nurse?', and 'What kind of effort are you currently making to maintain your heart health?' The interviews were carried out in quiet and comfortable places where interviews would not be interrupted, such as an area in the hospital or the participant's residence, and the in-depth interview data derived from the field work stage were analyzed using Strauss and Corbin's grounded theory [20]. According to the procedures of grounded theory, we analyzed the interview data through the three coding stages called open coding, axial coding and selective coding. Open coding is the first coding phase for identifying the meaning of each line of the interview contents and labeling it, axial coding is the process of identifying the relationships between the labeled categories by constantly comparing them, and selective coding is the final coding stage to identify the core category among the data categories identified through previous coding phases and link and integrate the major categories around the core category [20]. During the analysis, the investigator used the constant comparison method [20], which is the method of comparing the data with each other and closely examining the similarities and differences, identified the categories generated during the interviews, and continuously conducted interviews until new categories did not emerge any more. All the contents of interviews were transcribed by the investigators. Two investigators derived key concepts and divided the domains based on independently transcribed contents, and they consulted two qualitative research experts during the analysis. The general characteristics of the participants are shown in Table 2.

Table 2 Characteristics of Interviewed Participants Click for larger image

3) Final analysis stage

In the final analysis stage, the results of the theoretical and fieldwork stages were compared and analyzed to define the integrated concept of health literacy for patients with cardiovascular disease [19]. By synthesizing the analysis data according to the contents of each of the major areas identified in the theoretical and fieldwork stages, the attributes and indicators of the concept of 'health literacy of patients with cardiovascular disease' were derived.

1) Dictionary definition of health literacy

The most commonly used Korean translation for health literacy literally means 'health information comprehension ability.' In Korean dictionaries, the term 'health' is generally defined as 'soundness or robustness of the mind and body or the condition of being mentally and physically sound and vigorous', and 'information' is defined as knowledge acquired by organizing facts or data gathered through observation or measurements so that the data can be practically useful in solving a problem or such data' [21]. In addition, 'comprehension ability' is defined as 'the ability to discern and understand facts or something based on reasonable judgement and thoughts' [21]. Therefore, taken together, health literacy can be defined as the ability to discern and understand data and knowledge related to mental and physical soundness or robustness.

2) Concepts of health literacy in related disciplines

The term 'health literacy' was first introduced in 1974, and the word was used in a study by Simonds (1974) upon the impact of health information on the health care system, education system, and the mass media. According to the definition of the American Medical Association, it is a collection of skills needed in a health care environment, such as basic oral reading and arithmetic skills [23, 25]. The American Medical Association defines health literacy as "the ability to obtain, process, and understand basic health information and services needed to make appropriate health decisions and follow instructions for treatment" [23]. Therefore, health literacy is individual, social, and cognitive skills that enable individuals to understand and use information to solve their health problems and maintain good health status, and it is a result of typical health education activities [24]. In Korea, several translations for health literacy are interchangeably used, and Korean translations have literal meanings such as 'medical information utilization ability', 'health literacy', and 'health information comprehension ability.' However, there is not yet a single established standard Korean term for health literacy [25]. In addition, as various types of mass media are developed, new capabilities and skills are increasingly required to have health literacy, so the concept of health literacy is sometimes extended to include media literacy or computer literacy [10].

3) Trends in studies on health literacy in nursing and healthcare

In Korea, research on health literacy began to be conducted relatively later compared to other countries and has been carried out mainly in the field of medicine since 2000 [9]. The population groups mainly studied in nursing studies were adults aged 40 years or over and older people aged 60 years or over. 'Health literacy' was once translated into the Korean expression meaning 'medical information comprehension ability', and it has been recently translated into Korean expressions which literally mean 'health literacy', 'health information comprehension ability', or 'health information utilization ability'. In addition, according to the research characteristics, Korean translations with the literal meaning of 'linguistic health information comprehension ability' and 'functional comprehension ability' have also been used [26]. A prior study analyzed the concepts of health literacy presented in studies published in Korea, using Rodgers' evolutionary concept analysis method. This study identified 'information seeking, information understanding, and information utilizing' as the attributes of health literacy, and identified health status, health beliefs, socioeconomic status and information quality as the antecedents of health literacy, and derived the improvement of self-care, improvement of interactions, and reduction of social costs as the consequences of health literacy [18]. The concept of 'oral health literacy' identified in the field of dentistry has been defined and used as 'the degree to which individuals have the capacity to obtain, process, and understand basic health information and services needed to make appropriate oral health decisions' [27]. The concept of 'mental health literacy' was used to assess mental health in married immigrant women, is a concept that applies health literacy to mental symptoms from a social perspective, and it has been defined as the knowledge and beliefs of individuals who are able to recognize and manage their mental health problems such as depression [28]. The term 'e-health literacy', which is a word recently created as a result of the recent development of science and technology, refers to the ability to search, understand, and evaluate health information for solving health problems through the Web or the Internet, and it can be regarded as a concept generated in connection with the social changes due to technological development such as the use of computers and the spread of smart phones [29].

4) Antecedents, dimensions, attributes, indicators, and provisional definition of health literacy of patients with cardiovascular disease

The antecedents of health literacy for patients with cardiovascular disease identified in the theoretical stage were physical factors (objective health status, age, and accompanying diseases), emotional factors (health belief, family support, and subjective health status), and social factors (culture, education level, occupation, and economic level). It was found that health literacy for patients with cardiovascular disease can be divided into the individual functional dimension and the interrelational dimension. The individual functional dimension was found to include health information search ability and information utilization skills as well as literacy skills such as reading, writing, and numeracy, while the ability to communicate with the medical team was shown to be an attribute of the interrelational dimension. In addition, health literacy for patients with cardiovascular disease has been reported to be closely associated with positive health outcomes and is evaluated to be a predictor of the health status of patients with cardiovascular disease. In short, as health literacy for patients with cardiovascular disease enables patients to recognize their own diseases and understand the medical team's instructions related to the diseases and increases their motivation for health behaviors, health literacy for patients with cardiovascular disease has been reported to lead to successful implementation of health behaviors. Many studies have shown that the implementation of health behaviors are manifested in different forms. In other words, previous studies have demonstrated that the implementation of health behaviors affected medication adherence, which is very important for patients with cardiovascular disease, were manifested in diverse forms of health management, including dietary management such as sodium intake control, stress management, temperance, reduction or cessation of cigarette smoking, and weight control, and influenced communication with the medical team, such as regular visits to medical institutions (Table 1). As a result, in patients with cardiovascular disease, the level of health literacy has been shown to influence the indicators, such as compliance with medical instructions (medication adherence and the improvement of medication compliance), elimination of risk factors (reduction or cessation of smoking, temperance, and weight control), management of influencing factors (changes in eating habits and stress control), and interactions with the medical team (outpatient visits, taking regular examinations, participation in educational programs, participation in immunization programs). In short, health literacy for patients with cardiovascular disease is affected by its antecedents including physical, emotional, and social factors, and it refers to the ability of patients with cardiovascular disease with different levels of literary skills to communicate appropriately with the medical team and to search and use various kinds of health information to maintain and promote health.

1) Individual functional dimension

2) Interrelational dimension