INTRODUCTION
Increased life expectancy and improved quality of life have increased social awareness of well-being and well-dying [1]. Well-dying encompasses the notion of experiencing a peaceful and contented death [2]. Recognition of a good death refers to having a positive attitude toward death, including death for human values or beliefs in the process of death, having autonomy in medical care or death methods, and dying without physical pain [3]. However, the progress in medical technology and pharma-ceuticals, while beneficial in treating acute illnesses, has also led to the prolonged suffering of patients with little chance of recovery. Consequently, many families find themselves grappling with the difficult decision of whether to continue life-sustaining treatments for their loved ones [4]. As such, decision-making on life-sustaining treatment is required when death is imminent, but judgment on life-sustaining treatment is often made by the family on behalf of patients who are unconscious or unable to make decisions [5]. Life-sustaining treatment comprises medical interventions such as ventilator support, hemodialysis, cardiopulmonary resuscitation (CPR), and chemotherapy administration aimed at prolonging patients’ lives rather than providing therapeutic benefits [6]. This approach often prolongs the dying process and sustains life without meaningful improvement raising questions about individuals’ rights to self-determination regarding their medical care. In this process, the question of the right to self-determination on life-sustaining treatment was raised, and the Life-sustaining Treatment Decision Act was enacted after social discussion [7]. Under the Life-sustaining Treatment Decision Act, Advance Directives (AD) enable adults aged 19 and above to document their preferences regarding the withdrawal of life-sustaining treatment and admission to hospice care, which are then validated by medical institutions. Since the implementation of the Life-sustaining Treatment Decision Act, the number of registered ADs has been increasing, and as of the end of August 2023, the number of people who wrote an AD was over 1.94 million [8]. However, most of the writers of ADs are in their 60s or older, and the writing rate of middle-aged adults is slightly above 10% [9].
Theory of Planned Behavior (TPB) is a theory that suggests that behavioral intention is a major factor to predict and explain human behavior. TPB is a theory on how individuals’ behavioral intentions are shaped by their attitudes toward the behavior, subjective norms (including expectations and pressures from peers or society), and perceived behavioral control. Perceived behavioral control refers to an individual's perception of their ability to effectively perform and regulate the behavior in question [10]. TPB has been useful in identifying individual behavioral intentions in various fields, and has verified in many related studies [11]. Several studies have been conducted on the intention to sign an AD to explore the scientific nature and practicability of TPB theory [12,13]. However, there are very few studies that have identified the factors influencing the intention to sign an AD for middle-aged adults in Korea by applying the TPB.
Middle age represents a pivotal stage in Korean society's demographic landscape, portraying a period where individuals often find themselves balancing the responsibilities of parenthood while also providing care and support to aging parents [14]. It is a time when parents decide on end-of-life treatment, experience the death of people around them, and think about their own future death [15]. Middle-aged adults provide primary care at their parents’ death beds and participate in important decision-making in the process of end-of-life treatment, and they may experience a similar situation in the near future. Therefore, in middle age, it is necessary to contemplate and prepare for a good death, and a crucial part of the preparation is writing an AD in advance.
In Korea, there remains a notable lack of awareness surrounding AD, and the infrastructure to support AD implementation has yet to be fully established [16]. Therefore, there is an urgent need to invigorate research efforts focused on AD to enhance awareness and uptake, ultimately ensuring that individuals are adequately prepared for a dignified end-of-life experience while in good health. The purpose of this study is to identify the influencing factors on the intention to sign an AD for middle-aged adults in Korea based on Ajzen's TPB.
METHODS
Research design
This study is a descriptive correlation study to determine the factors influencing middle-aged adults’ intention to sign the AD based on the TPB in Korea.
Participants
This study targeted 40 to 64 years old in Korea who had no chronic diseases.
The minimum adequate sample size was calculated to be 198 considering the size of the two-sided test effect for the regression analysis were 0.15 (medium size), 0.05 significance level, and 0.90 power by using the G-power 3.1.9 program [17]. Anticipating for the 20% of dropout rate, a total of 240 questionnaires were distributed, and 240 (100.0%) were retrieved. Excluding 10 with insufficient responses, 230 of retrieved questionnaires (95.8%) were used for the final analysis of this study.
Research tool
Well-dying recognition
To assess well-dying recognition, the well-dying recognition tool developed by Jeong [18] was used. Well-dying recognition consists of five subdomains with 23 questions: 3 on physical well-dying, 6 on psychological well-dying, 6 on social well-dying, 2 on spiritual well-dying, 3 on independent well-dying, and 3 on autonomous well-dying. Each item is rated on a 5-point scale, with a score ranging from 23 to 115 points. The higher the score, the higher the well-dying perception. The Cronbach's alpha, as reported by Jeong [18] during the development of the instrument, was 0.93. In our study, the Cronbach's alpha remained consistent at 0.93, indicating a high level of internal consistency reliability.
Attitudes toward signing the AD
To evaluate the attitude toward signing the AD in this study, we utilized the instrument developed by Lee [19]. Our study used the attitude toward signing the AD modified and supplemented in accordance with the purpose of this study. Attitude toward signing the AD consists of eight items in total. Each item is rated on a 7-point Likert scale, with a score ranging from 8 to 56 points. The higher the score, the more positive the attitude. The Cronbach's alpha for the attitude toward signing the AD instrument, as reported by Lee [19] during its development, was 0.98. In our study, the Cronbach's alpha for the same instrument was 0.90, indicating a high level of internal consistency reliability.
Subjective norms toward signing the AD
To evaluate the subjective norm toward signing the AD in this study, we utilized the tool developed by Lee [19]. Our study used the subjective norm toward signing the AD modified and supplemented in accordance with the purpose of this study. Subjective norm toward signing the AD consists of three items in total. Each item is rated on a 7-point Likert scale, with a score range, with a score ranging from 3 to 21 points. The higher the score, the more positive the subjective norm. The Cronbach's alpha for the subjective norm toward signing the AD instrument, as reported by Lee [19] during its development, was 0.74. In our study, the Cronbach's alpha for the same instrument was 0.76, indicating a satisfactory level of internal consistency reliability.
Perceived behavioral control toward signing the AD
To assess perceived behavioral control toward signing the AD in this study, we employed the tool developed by Lee [19]. Our study used the perceived behavioral control toward signing the AD modified and supplemented in accordance with the purpose of this study. Perceived behavioral control toward signing the AD consists of four items in total. Each item is rated on a 7-point Likert scale, with a score ranging from 4 to 28 points. The higher the score, the higher the perceived behavioral control. The Cronbach's alpha for the perceived behavioral control toward signing the AD instrument, as reported by Lee [19] during its development, was 0.89. In our study, the Cronbach's alpha for the same instrument was 0.81, indicating a good level of internal consistency reliability.
Intention of signing the AD
To assess the intention of signing the AD, Intention to sign the AD was developed by Lee [19]. Our study used the intention of signing the AD modified and supplemented in accordance with the purpose of this study. Intention of signing the AD consists of three items. Each item is rated on a 7-point Likert scale, with a score ranging from 3 to 21 points. The higher the score, higher the intention of signing the AD. The Cronbach's alpha for the perceived behavioral control toward signing the AD instrument, as reported by Lee [19] during its development, was 0.89. In our study, the Cronbach's alpha for the same instrument was 0.88, indicating a high level of internal consistency reliability, with minimal variation from the original study.
Data collection methods and ethical considerations
This study was approved by the Institute of Research Board (IRB No: CKU-23-01-0106) of the Catholic Kwandong University for the rights and ethical protection of the subjects. Data was collected from June 15 to June 20, 2023, from middle-aged adults aged 40 to 64. To collect data, consent was sought from online communities such as retirement community nationwide, and online surveys (Google questionnaires) were posted on the community bulletin board. The study's purpose and survey preparation process, along with details regarding questionnaire participation, confidentiality assurances, and procedures for withdrawing from the research, were posted on the online community bulletin board. Participants who agreed to take part were invited to complete the survey. The investigation was anonymous, but a mobile phone number was required to prevent duplicate participation and provide compensation. The questionnaire required approximately 10 to 15 minutes to complete, and participants were offered a specific incentive as a token of appreciation for their time and participation in the survey.
Data analysis
The collected data were analyzed using the SPSS 28.0 (IBM Corp., Amonk, NY, USA) program. Descriptive statistics analyzed the general characteristics of the subjects. The degree of well-dying recognition, attitude, subjective norms, perceived behavior control toward signing the AD, and intention to sign the AD were analyzed using the mean and standard deviation. Well-dying recognition, attitude, subjective norms, perceived behavioral control, and intention according to general characteristics were analyzed using t-tests and ANOVA. Post-verification was conducted using the Scheffé test. The correlations between the subjects’ well-dying recognition, attitude, subjective norms, perceived behavioral control, and intention were analyzed as Pearson's correlation coefficient. Factors affecting the intention to sign the AD of the target were analyzed with a hierarchical regression analysis.
RESULTS
General characteristics of study subjects
The average age of the study subjects was 46.74±6.29 years old, with 130 females (56.5%) and 100 males (43.5%). 185 People (80.4%) were married, 121 people (52.6%) had no religion, 57 people (68.3%) had a college or higher education, and 88 people (38.3%) had a monthly income exceeding 5 million won. There were 170 people (73.9%) who lived a leisurely lifestyle, 138 (60.0%) who considered themselves healthy, and 133 (57.8%) who experienced the death of neighbors within the last three years. 164 People (71.3%) knew about the AD, and 78 people (33.9%) thought that healthy conditions were the optimal time to sign the AD (Table 1).
Table 1.
Differences in the intention of signing the advance directives according to general characteristics (n=230)
Degree of well-dying recognition, attitude, subjective norms, perceived behavioral control toward signing the AD and intention to sign the AD
Subjects’ well-dying recognition was 3.82/5 points, with sub-areas physical well-dying recognition 3.81/5 points, psychological well-dying recognition 3.81/5 points, social well-dying recognition 3.69/5 points, spiritual well-dying recognition 3.22/5 points, independent well-dying recognition 3.78/5 points, and autonomous well-dying recognition 3. 82/5 points. Subjects’ attitudes, subjective norms, perceived behavioral control toward signing the AD, and intention to sign the AD were 5.30/7 points, 4.80/7 points, 5.25/7 points and 5.18/7 points respectively (Table 2).
Table 2.
Degree of variables (n=230)
Differences in intention to sign the AD according to general characteristics
There was a statistically significant difference in intention to sign the AD according to age (F=3.45, p =0.033), level of education (F=7.27, p < 0.001), employment status (t=-2.16, p =0.032), and AD awareness (t=-4.62, p <0.001) timing of signing the AD (F=2.69, p =0.047) (Table 1).
Correlation between well-dying recognition, attitude, subjective norms, perceived behavioral control toward signing the AD and intention to sign the AD
There were significant, positive correlations between intention to sign the AD and physical well-dying recognition (r=0.29, p <0.001), psychological well-dying recognition (r=0.34, p <0.001), social well-dying recognition (r=0.34, p <0.001), spiritual well-dying recognition (r=0.26, p <0.001), independent well-dying recognition (r=0.32, p <0.001), autonomous well-dying recognition (r=0.41, p <0.001), attitudes toward signing the AD (r=0.67, p <0.001), subjective norms toward signing the AD (r=0.44, p <0.001) and perceived behavioral control toward signing the AD (r=0.57, p <0.001) (Table 3).
Table 3.
Correlation among variables (n=230)
1: Physical well-dying recognition, 2: Psychological well-dying recognition, 3: Social well-dying recognition, 4: Spiritual well-dying recognition, 5: Independent well-dying recognition, 6: Autonomous well-dying recognition, 7: Attitude toward signing the AD, 8: Subjective norm toward signing the AD, 9: Perceived behavioral control toward signing the AD, 10: Intention of signing the AD.
Table 4.
Factors influencing intention of signing the advance directives (n=230)
| Model | Model I | Model II | Model III | |||
|---|---|---|---|---|---|---|
| β | p | β | p | β | p | |
| (Constant) | <0.001 | <0.001 | 0.754 | |||
| Age (60-64)a | 0.00 | 0.981 | 0.01 | 0.897 | -0.01 | 0.911 |
| Level of education (college)b | 0.05 | 0.494 | -0.06 | 0.332 | -0.04 | 0.433 |
| Employment status (unemployed)c | 0.19 | 0.068 | 0.08 | 0.177 | 0.09 | 0.058 |
| AD awareness (aware)d | 0.27 | <0.001 | 0.18 | 0.004 | 0.08 | 0.122 |
| Timing of signing the AD (healthy)e | 0.15 | 0.021 | 0.16 | 0.013 | 0.12 | 0.021 |
| Physical well-dying recognition | 0.02 | 0.860 | 0.01 | 0.920 | ||
| Psychological well-dying recognition | 0.06 | 0.578 | 0.02 | 0.837 | ||
| Social well-dying recognition | 0.07 | 0.518 | 0.07 | 0.412 | ||
| Spiritual well-dying recognition | 0.10 | 0.147 | 0.05 | 0.330 | ||
| Independent well-dying recognition | 0.05 | 0.574 | 0.04 | 0.587 | ||
| Autonomous well-dying recognition | 0.20 | 0.021 | -0.01 | 0.872 | ||
| Attitude toward signing the AD | 0.43 | <0.001 | ||||
| Subjective norm toward signing the AD | 0.23 | <0.001 | ||||
| Perceived behavioral control toward signing the AD | 0.16 | 0.020 | ||||
| R2 | 0.13 | 0.26 | 0.55 | |||
| Adjusted R2 | 0.11 | 0.22 | 0.52 | |||
| ∆R2 | 0.13 | 0.13 | 0.29 | |||
| F (p) | 6.59 (<0.001) | 6.86 (<0.001) | 18.47 (<0.001) | |||
Factors influencing intention of signing the AD
Before conducting hierarchical analysis to determine the factors influencing participants’ intention to sign the AD, the conditions for regression analysis were carefully assessed. The Durbin-Watson statistic, indicating autocorrelation, yielded a value of 1.99, suggesting minimal autocorrelation given its proximity to 2. Additionally, a multicollinearity analysis was performed, revealing that the variance inflation factor ranged from 1.01 to 3.29, all well below the threshold of 10, signifying no significant multicollinearity issues. Moreover, tolerance values fell within the acceptable range of 0.1 to 1.0, ranging from 0.30 to 0.99, further confirming the absence of multicollinearity problems. In Model I, general characteristic variables were used as control variables that affect a subject's intention to sign the AD. Factors that affected the intention to sign the AD were recognition of AD (β=0.27, p <0.001), timing of signing the AD (β=0.15, p =0.021). They showed a significant 11% explanation of intention to sign the AD.
In Model II, a sub-domain of well-dying recognition was added to Model I. As a result of regression analysis, recognition of AD (β=0.18, p =0.004), timing of signing the AD (β=0.16, p =0.013), and autonomous well-dying recognition (β=0.20, p =0.021) were influencing factors, and it showed 22% explanatory power, up 11% increased from Model I's explanatory power (F=6.86, p <0.001).
In Model III, the TPB variables for Model II, such as attitude, subjective norms, and perceived behavior control toward signing the AD were added. Factors affecting the intention to sign the AD included attitudes (β=0.43, p <0.001), subjective norms (β=0.23, p <0.001), perceived behavioral control (β=0.16, p =0.020), and timing of signing the AD (β= 0.12, p =0.021). The Adjusted R2-value was 0.52, a significant explanatory power of 52%, 29% increased from Model II's explanatory power (Table 4).
DISCUSSION
This study was conducted on middle aged adults to understand the intention to signing the AD and well-dying. In this study, the intention score of 5.18 out of 7 points aligns closely with the intention score of 3.47 out of 5 points observed in a study involving college students [12]. However, it was higher than the scores in the study of the elderly [20], and long-term care recipients [21]. The high intention among middle-aged adults to sign the AD can be attributed to several factors. Middle-aged adults often find themselves burdened with supporting their elderly parents, experiencing frequent encounters with death among their peers, and confronting their own health concerns that may prompt contemplation about end-of-life care. Nevertheless, considering that most of the writers of ADs are over 60 years old [9], the difference in the score of intention to sign the AD in previous studies and this study needs to be verified through future studies considering age and demographic characteristics.
In this context, the intention to sign the AD is likely elevated as individuals recognize the importance of facilitating decisions regarding life-sustaining treatment. This observation aligns with the findings of Hirayama et al. [22] and underscores the significance of AD in providing individuals with the means to articulate their preferences for end-of-life care in the face of such challenges. The intention to sign the AD was higher in the subjects who were aware of the AD than those who were not. This supports the results from the previous studies [20,21,23]. In addition, the intention of signing the AD varied based on the timing of signing the AD, a finding consistent with previous research [24]. Fear of death may intensify upon being diagnosed with cancer or finding one-self in a situation where treatment decisions are required while unconscious [25]. However, making decisions regarding life-sustaining treatment in advance could potentially mitigate this anxiety. Therefore, signing up for AD when one's mental faculties are clear and health is stable becomes imperative in alleviating such anxieties.
According to the study, the factors that affect subject's intention to sign the AD were attitude, subjective norms, perceived behavioral control toward signing the AD, and timing of signing the AD, which showed collectively an explanatory power of 52%.
In this study, the most influential factor on the intention to sign the AD is the attitude. This was similar to the results shown as significant influencing factors in previous studies [12,13,23]. The increased intention to sign the AD for life-sustaining treatment may be attributed to the enactment of laws on life-sustaining treatment and greater public awareness of AD. In the future, education will be essential in fostering a positive attitude toward the preparation of AD.
The subjective norm regarding the signing of an AD was the second most influential factor in the intention to sign the AD. This was similar to Kim's [23] study on in breast cancer patients and a study [13] on family caregivers of dementia patients. However, it was different from the research of Lee et al. [12]. Subjective norms involve the influence of normative expectations from reference individuals or groups and the extent to which individuals try to conform to those around them [26]. In middle age, the subjective norm for signing an AD is considered high due to significant influence from one's surroundings, particularly as individuals reflect on and prepare for their own death or that of their parents. On the other hand, in a study involving college students [12], important people around college students are presumed to have different results from this study. This is likely because these individuals have little to no experience with death, or they do not think deeply about it, making it difficult for them to recognize the significance of AD. Support and advice from people around them that are meaningful to individuals are needed to improve the subjective norms for signing AD.
The third factor influencing the intention to sign the AD is perceived behavioral control. This study revealed a similar result to previous studies [12] confirming that perceived behavioral control had the greatest influence on the intention to sign the AD [27-29]. Perceived behavioral control refers to the degree to which one perceives how well one can actually perform and control an action [10]. To increase perceived behavioral control for signing the AD, it is necessary to ensure individuals feel they can sign the AD without discomfort and that the signing process is not difficult. To this end, it is necessary to increase the accessibility of institutions that can sign the AD and simplify the method of signing.
Timing of signing the AD was the last influential factor on the intention to sign the AD. Similar results were found in the breast cancer patient study [23] and the cancer patient study [24]. The preparation of AD protects individual autonomy as much as possible and minimizes the pain of the end-of-life process by making decisions about end-of-life treatment [25]. The optimal time to write an AD is while the patient is still healthy, before illness becomes predominant, or before a patient has been transferred to a long-term care facility [30].
Well-dying recognition was not an influential factor of the intention to sign the AD, but in Model II, autonomous well-dying recognition was an influential factor in the intention to sign the AD. Well-dying refers to a state in which the quality of death is ensured [31]. Just before death, patients often die in an untreatable condition that disregards human dignity, leading to a prolonged, meaningless existence filled with relentless pain and a loss of purpose in life [32]. Therefore, it is necessary to make autonomous decisions about death and prepare for a meaningful death through AD for life-saving medical treatment. The purpose of signing the AD is to make an autonomous decision on one's own death [5], and the decision on the suspension of life-sustaining treatment is similar to the intention of signing the AD. Well-dying education, along with extensive awareness campaigns and educational efforts aimed at reducing fear of death and fostering open communication about it, will positively influence the signing of advance directives.
This study identified the factors influencing the intention to sign the AD by applying the TPB for middle-aged adults in Korea, and it seems necessary to increase the explanatory power of the factors influencing middle-aged adults’ intention to sign the AD by adding more related factors in future research.
In the future, research should be conducted to confirm the relation-ship between the intention to sign the AD and actually signing one. Spe-cific promotional measures should be developed to encourage middle-aged adults to prepare an AD. Furthermore, strategies are needed to improve access for patients and their families to sign the ADs in hospitals and community institutions. However, the data from this study have limitations due to the convenience sampling method used via online surveys, which may affect the generalizability of the results. Future sampling should consider the age distribution of the population to ensure more representative findings.
CONCLUSION
In this study, the factors influencing the intention to sign the AD in middle-aged adults in Korea were identified. There were four factors influencing the signing of the AD: attitude, subjective norms, perceived behavioral control, and the timing of signing, collectively accounting for 52% of the total variance. The purpose of the signing of the AD is to increase human dignity until the end and prepare in advance for a meaningful death. Therefore, it is necessary to strengthen education and publicity efforts to make it easier for middle-aged adults to sign the AD.
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