Introduction

Lifestyle is becoming a major subject in the development of academic meaning and socioeconomic aspects in fields such as health promotion, marketing, and sociology, focusing on human behavior [1–3]. Lifestyle is defined as a lifestyle formed according to external environmental factors that reflect an individual’s life consciousness, values, and personality while consuming time and money [4]. Lifestyles that reflect such multi-faceted aspects are being studied to identify the characteristics and trends of society, groups, and individuals or small groups [5].

Recently in the field of health promotion, interest in lifestyle has increased as it increases life expectancy while reducing the prevalence of chronic diseases, premature mortality, and non-communicable diseases [6,7]. Such a lifestyle is reported to be an important determinant of health and well-being in human life, and the need for a healthy lifestyle approach has been emphasized (WHO, 2021). Recently, an academic approach to lifestyle, which determines health and well-being, has been used in the analysis of causal relationships, risk factors, interventions, and the development of evaluation tools [3,8,9].

In the field of health promotion, the importance of an academic approach that can measure and evaluate a multi-dimensional and dynamic lifestyle has been emphasized to form and improve a healthy lifestyle [10]. Previous studies have quantified the frequency and exposure of behaviors such as physical activity, smoking, and drinking to analyze lifestyle characteristics; however, tools that can measure habits, behaviors, management, and diversity in daily life are limited [11]. Such a limitation makes it impossible to grasp the practice trend of a lifestyle that reflects the intensity of health-related routines and habits repeated in daily life and the diversity of activities [12].

Previous studies have focused on behaviors such as obesity, physical activity, diet, drinking, and smoking as lifestyle factors for human health and well-being [13,14]. These factors have previously been emphasized in the healthcare field [15]. On the other hand, the importance of relationships and participation in social factors has been emphasized before [16], but the need for a comprehensive approach that includes them as key relatively unnoticed factors is increasing [16,17].

Considering this research situation, it is essential to systematically measure lifestyles to achieve health and physical, mental, and social well-being [18]. However, no evaluation tool can measure the diversity and degree of a comprehensive healthy lifestyle in daily life, and the need for development has been confirmed. This study aims to develop an assessment tool to measure the diversity and degree of lifestyle behaviors related to human health. Therefore, we attempted to develop quantitative measurement items that reflect the comprehensive concepts of health and lifestyle and to verify their validity.

Methods

The Delphi technique, developed by Dalkey and Helmer (1963) [19] at the Rand Corporation in the 1950s [20], is designed to gather purposeful opinions from experts identified in each field [21]. We used the modified Delphi method, which obtains consensus on the opinions of a group of experts through a series of structured open and closed questions [22]. The study was approved by the Yonsei University Mirae Institutional Review Board, considering the ethical aspects of the participants (Approval number:1041849-202211-SB-207-02). The data collection for this study was conducted from March 1, 2023, to April 30, 2023. Also, this study was conducted through an online survey, and given the impracticability of obtaining written consent, it proceeded after obtaining approval from the research ethics committee for an exemption from written consent.

The Delphi method

The study was conducted with participants who provided consent to potential expert panels. Demographic information was collected from the participants. Participants were instructed to read the guidelines introducing the concept of multi-faceted lifestyle components developed to create lifestyle assessment tools in the introduction of the survey attached to the email (Appendix 1). The first section explains the lifestyle factors of physical activity, eating habits, activity participation, and activity diversity, based on a literature review and previous studies. Participants were then shown the following sections consisting of 72 questions:18 areas of physical activity, 18 areas of nutrition, 18 areas of social relationships, and 18 areas of social participation. These items were developed based on literature review [9,23–26].

The Delphi survey consisted of three steps (Fig 1). In the first stage, a literature review of the development of the questions was derived from previous studies. In the second stage, the Delphi was conducted with experts, and the Delphi had a total of two rounds. The research team provided information about the study and obtained consent from all participants from a panel of experts before the study began. The participants responded to the first- and second-round questionnaires delivered through e-mail. Each round of the survey was conducted for one week, and to maximize the response rate, participants who did not respond were given additional time to send a reminder and answer a day after the deadline. In the final stage, active, balanced, connected, diversity (ABCD) was developed that reflected the opinions of experts.

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Fig 1. Research process.

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Round 2

The Round 2 survey was revised to reflect the responses of the expert panels in Round 1. It consisted of 72 closed-ended questions in four domains (physical activity, nutrition, social relationships, and social participation). Each participant was informed via e-mail and asked to answer each question using a 4-point Likert scale (strongly irrelevant, not relevant, relevant, or strongly relevant). Neutral (ordinary) scores were not included (Fig 2) to obtain clear opinions from the expert panel. In the second round, four items from the first round were modified.

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Fig 2. Examples assess the relevance of each item.

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Data analysis

To derive opinions, the collected response data were analyzed for means, standard deviations, medians, content validity, convergence, and stability. For general information from the expert panel, the mean, standard deviation, and median were obtained using descriptive statistics. The convergence, stability, and consensus for the collected values were calculated to confirm the validity of the item content. The degree of convergence has a value of zero when all opinions converge at a point and increases when opinion deviations are large. This means that closer to zero, the more valid the item [23–8]. The calculation formula for the CVR value is as follows (Fig 3):

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Fig 3. Formulation of CVR (content validity ratio).

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During repeated survey, the smaller the response difference of the panel, the higher the stability if the response is constant, the higher the stability if the response is 0.5 ~ 0.8, and the additional investigation is required if it is 0.8 or more [27], The degree of agreement has a value of 1 when the opinion is congruent, and the closer to 1, the more valid the item [28]. For the fitness value of each item, the content validity ratio (CVR) value was analyzed based on the criteria of Lawshe (1975) [29], and the data were analyzed based on 0.51, the minimum value according to the 14 expert panels participating in this study.

Results

Demographics of the expert panels

Sixteen Delphi expert invitations were sent to potential participants. Of these, 14 participants responded by expressing their consent to participate. A panel of 14 experts who participated in this study completed the first and second surveys. The expert panel that participated in this study had a 100% response rate and no participants dropped out. The demographic characteristics of the participants are shown in Table 1. Seven (50%) participants were female and seven (50%) were male. They had an average of 8.86 years of experience in their major fields of expertise. The expert panel comprised various health experts in nursing, nutrition, occupational therapy, and physical therapy.

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Table 1. Demographics of the expert panels.

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Results of round 1

The categories and items of the detailed results of the Delphi Round 1 are presented in Table 2. Fourteen experts responded to all questions in the first-round survey, and the first round consisted of 76 questions, including 72 closed-ended questions and 4 open-ended questions in four categories. In the physical activity category, the range of the CVR ratio was 0.57 ~  1.00, and content validity was verified for all items. In the nutrition category, among the imbalanced items, the CVR ratio of two items asking about eating speed, drinking, and smoking was 0.43, falling short of the standard value. In the case of the social relations and social participation categories, the CVR ratio of each item was 0.43, and consensus was not reached. Four questions for which a consensus was not reached in the first Delphi survey were modified according to the opinions of experts written in open-ended questions, and then a second Delphi was conducted.

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Table 2. Lifestyle assessment in the round 1st survey.

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Results of round 2

The detailed results of the Delphi Round 2 are presented in Table 3. Fourteen experts responded to all the questions in the second survey. In the first round, the questionnaire was administered by modifying four items that did not reach consensus because they did not reach the standard CVR ratio. In the physical activity category, content validity was verified for all items, with CVR ratios ranging from 0.57 to 1.00. In the case of nutrition, the two items asking about eating speed, township, and smoking, which were not agreed upon, were corrected. The CVR ratios were 0.86 and 0.57, respectively, confirming their validity. However, there was no consensus on nut consumption, with a score of 0.43. In the social relationship category, the question of whether to live alone was modified to reflect the first open-ended opinion, but the CVR ratio was 0.29; thus, a consensus was not reached. In the social relations category, the CVR ratio of the question asking about regular activity participation was 0.43, which did not reach a consensus, and the question of whether there was help for community participation reached agreement with a CVR ratio of 0.57 through modification reflecting the first open-ended opinion was reached.

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Table 3. Lifestyle assessment in the round 2nd survey.

https://doi.org/10.1371/journal.pone.0316597.t003

The second Delphi results showed a relatively low standard deviation and relatively high content validity compared with the first (Table 4).

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Table 4. Average of the expert panels.

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Discussion

The necessity of developing an assessment tool that can identify lifestyle tendencies reflecting the diversity of activities and the intensity of health-related routines and habits repeated in daily life was confirmed. The development of these assessment tools will support the multi-faceted and systematic measurement of an individual’s physical, social, and mental health. The field of health promotion is increasingly emphasizing the importance of evaluating a multi-dimensional and dynamic lifestyle as an approach to shaping and improving a healthy lifestyle [10]. In addition, Studies [30] and [31] reinforce our understanding that healthy lifestyles support physical and mental well-being, with [30] specifically linking lifestyle diversity to successful aging.However, in previous studies, quantifying and analyzing the frequency and exposure of behaviors such as physical activity, smoking, and drinking had limitations in measuring aspects of habit, behavior, management, and diversity [11]. Accordingly, we decided to develop a comprehensive evaluation tool that could evaluate an individual’s lifestyle in a multi-faceted and systematic manner by applying the Delphi technique. In this study, we discuss our proposal based on the consensus of an expert panel.

Previous studies have shown that physical activity can be considered a lifestyle factor [32]. Most national and international physical activity guidelines and statements recommend regular physical activity to prevent diseases, promote health, and delay loss [33]. However, according to the expert panel, it was necessary to consider aspects of habits, behaviors, management, and variety and to identify individual preferences or tendencies, including quantified measures such as high-intensity, moderate-intensity, and low-intensity activities. Previous studies have reported that maintaining a healthy lifestyle increases a chronic disease-free lifespan and improves overall physical and emotional well-being [34,35]. One study [34] highlights the role of exercise in reducing chronic disease risks, while another [35] links lifestyle adherence with longer disease-free years. Conversely, being overweight or obese is associated with chronic illness and reduced quality of life [36]. This suggests that regular physical activity is necessary to improve health and quality of life. Therefore, when evaluating an individual’s multi-faceted lifestyle, it is necessary to assess various types of physical activities and habits.

Nutrition is described as a healthy lifestyle factor along with eating habits [32]. This study found that it is necessary to identify unbalanced eating habits, including balanced eating habits. Despite the CVR value of 0.43, nut intake was retained due to its established importance in studies on cardiovascular and immune health [37–40]. Adequate nutrition is critical for the optimal functioning of the body and for strengthening immune function, and nutritional imbalances can adversely affect the immune system [41]. Additionally, adequate nutrition, physical activity, and proper eating habits can reduce the risk of chronic diseases and improve the immune system [42]. A balanced diet that includes fruits, vegetables, whole grains, plant and animal proteins, and healthy fat is a good way to promote better health and proper functioning of the immune system [43]. A balanced diet cannot control infections but can improve the immune system and mental health [41] Therefore, when evaluating a multi-faceted lifestyle, it is necessary to evaluate balanced nutritional status and eating habits.

Social relationships are important factors in physical and psychological health [44]. Individual social relationships are a major factor in mental health, including depression and anxiety. Previous studies have reported that positive interactions with others and maintaining supportive relationships have a positive effect on physical and psychological health [45,46]. This study confirms that it is necessary to ask questions about the physical and human resources that have positive and negative effects on social relationships. However, the question of whether to live alone was 0.29 based on the second round CVR ratio, and a standard value was not reached. It was difficult to determine whether a person lived alone because the type of residence had changed owing to the rapid increase in single-person households in Korea. However, this question was not addressed in this study. Previous studies have reported that social relationships are divided into intra-family and non-family relationships and that objective characteristics of situations, such as the number of social contacts or proximity, are the characteristics of social relationships [47]. In addition, social relationships should consider the volume of relationships (how many social ties are nearby, available, and dependable) and the emotional volume (the degree of intimacy, understanding, and interest shared with others) [47]. Therefore, the question was not deleted, but it is necessary to conduct additional research on the factors of social relationships according to the presence or absence of single-person households in the future by reflecting the additional opinions of experts.

Social participation plays an important role in the quality of life as we age [48]. Social participation is defined as engaging in community activities that provide social interaction [49]. Social participation is an important factor in determining healthy aging [50]. Age, gender, health status, neighborhood, and social environment have been reported as additional factors [51–54]. that have complex relationships with social participation [55]. Similarly, the results of this study confirmed that questions on social participation require consideration of various factors. However, for the presence or absence of participation in religious activities, the second-round CVR was 0.43, and a reference value was not reached. This is because they do not consider non-religious people. However, in previous studies, religious participation has been reported to have potential effects on mental health as an important factor in social participation [56] and to play a positive role in the daily lives of the elderly [57]. Religious participation is closely related to the psychological, physical, and social dimensions of successful aging [58]. Religious participation should be considered when evaluating social participation, but a more subjective understanding of religiosity and participation in religious activities may be questioned. Therefore, the results need to be interpreted cautiously.

The limitations of this study were as follows. The first is the number of Delphi experts. The expert panel comprised a relatively small group of 14 members. Although useful results can be obtained with a panel of 4–11 people [59], there is a limit to generalization, considering that reliability increases as the number of panels increases. Nevertheless, unlike previous studies, this study is meaningful in that a panel of experts in various health-related fields was formed, and conclusions were drawn by collecting various opinions. Second, existing studies were reviewed to develop Delphi questionnaires. It cannot be ruled out that researchers may have missed various theories, backgrounds, and studies in this process. Third, the reliability and validity of the results were analyzed using the opinions of an expert panel. In future, additional studies on the validity and reliability of this questionnaire should be conducted with the public. Finally, the expert panel consisted of only Korean health experts. Therefore, this study reflects only a limited perspective on the Republic of Korea. Therefore, for an international version of this tool, expanding the panel to include experts from multiple countries would provide additional perspectives.

Conclusion

This study developed a multi-faceted lifestyle assessment tool using a modified Delphi technique. As a result, the 72 items were classified into eight subcategories and four categories. This assessment tool can systematically evaluate lifestyles to achieve health and physical, mental, and social well-being and can be used to identify individual lifestyles necessary for interventions in more depth. However, because the tool was developed in Korea, the possibility that it can be affected by various environmental factors, such as geographical and cultural factors, cannot be ruled out. Therefore, there is a need to conduct research on people living in various communities. Additional research should be conducted to confirm the reliability and validity of the evaluation tools developed.