Abstract
Hiring in-home paid caregivers (IPCs) to tend to older adults at home has been one of the popular long-term care strategies in several urban aging societies. Relevant studies in the Global South that provide empirical findings have been lacking. This study contributes to the literature on home care by conducting a qualitative analysis of work motivation and the quality of work life of female IPCs in Thailand. We found that work motivation involved the desire for personal economic improvement and the search for an emotional anchor. Analysis of quality of work life pointed to three major themes: great contribution but low recognition and support; interdependence as an ultimate career goal; and effective training as a key to opportunity and success. We proposed a theoretical extension to the existing care theories and suggested necessary policy interventions to sustain the supply of IPCs.
• illustrates the thematic analysis of the quality of work life of in-home paid caregivers given their characteristics, work conditions, and well-being; • proposes interdependence in worker–client relationships as a theoretical extension to existing care theories; and • simplifies the linkage of the findings, existing theories, and policy recommendations.
• propose policy interventions to improve work satisfaction and well-being; and • promote future research efforts to examine care coordination in-home–based geriatric care and the impacts of policy intervention on care outcomes.What this paper adds
Applications of study findings
Introduction
Caring for older persons has largely remained a family obligation across boundaries and cultures. However, paid home care has become increasingly visible in most cities worldwide due to the disruptive changes initiated by increased life expectancy, continued fertility decline, and increased urbanization in the structure and composition of families and households (Weeks, 2020). As a result, in-home paid caregivers (IPCs) have become indispensable. Without them, it would be difficult or impossible for older adults to “remain in the community” (Reckrey et al., 2021).
Thailand, a Buddhist-majority country in Southeast Asia with a population of 69.8 million, has demographically transitioned into one of the world’s most rapidly aging societies. The country has been ranked 6th after South Korea, Singapore, Taiwan, Macao, and the Maldives, with the largest growth rate of the older population between 2019 and 2050 (United Nations, 2019a). In addition, the percentage of the population aged 65+ in Thailand has reached 13.0 in 2020 and has been projected to increase to 19.6 and 29.6 by 2030 and 2050, respectively (United Nations, 2019b).
Although a universal health coverage program has covered the majority of Thai citizens' health expenditures since 2002, only a small subsidy has been given to support long-term care (i.e., up to 10,000 baht [THB]/year or approximately 0.7 USD/day 1 ). As a result, only relatively well-off families could afford long-term care services at home or care facilities. In addition, the absence of official statistics has rendered the estimation of the IPC supply of the country difficult. However, available data have revealed that the Ministry of Public Health of Thailand certified 77,853 caregivers in FY2016–2018, while the number of home- and bed-bound older adults reached 180,821 in the same period (National Health Security Office [NHSO], 2020).
Since the COVID-19 pandemic has stimulated a shift in long-term care orientation from facility care to home care (Reckrey, 2020), an urgent call should be made to stimulate recognition and responsive support (Esquivel, 2014). In this regard, this study aims to answer two research questions: (1) what motivates an individual to become an IPC and (2) how do IPCs perceive their quality of work life, that is, “a person’s feelings about every dimension of work” (Guest, 1979). Finally, the study discusses policy recommendations and its contribution to existing care theories.
Theoretical Background
The paper is critically based on the care diamond model (Razavi, 2007) and theories of care work (England, 2005). Razavi introduced the care diamond model, in which the four corners of the diamond represented four sectors of care provision, namely, family, state (public), market (private), and community (non-profit). However, female labor force participation and the apparent aging situation encouraged several societies to alleviate the long-term care burden of families.
Ochiai (2009) compared the welfare systems for older persons in China, Japan, Singapore, South Korea, Taiwan, and Thailand and revealed a difference in the reliance on non-family care providers and the prevalence of care coordination between sectors. Based on the findings, Thai families struggled the most in providing geriatric care, whereas public–private care coordination was strongly evident in Japan and South Korea.
With solid filial obligations and the desire for togetherness rooted in Thai society, IPCs were the preferred solution for many relatively well-off families. In this sense, we perceived this tendency as an extension of Razavi’s care diamond, where private agents (IPCs) and family were combined in a family setting as primary and assistive caregivers, respectively.
Regarding relationships with the families of older clients, IPCs could be included as family members or excluded (implicitly or explicitly) as mere employees (Barnhart et al., 2014). In addition, family involvement could be viewed as insufficient or over-stepping due to the unmet balance of care coordination between IPCs and family/unpaid caregivers (Kemp et al., 2013).
Apart from the care diamond model, we employed England’s theories of care to structure the analysis of the motivation and quality of work life of IPCs. Influenced by gender and Marxist feminism scholars, England (2005) developed five frameworks, namely, (1) devaluation, (2) public good, (3) prisoner of love, (4) commodification of emotion, and (5) love and money.
Frameworks (1)–(3) suggested that care work was frequently associated with low rewards, which leads to an inadequate supply of care workers. According to Framework (1), care was devalued because it was implemented by women, particularly marginalized ones. In addition, based on Framework (2), care typically yielded low rewards despite its diffused benefits to direct and indirect beneficiaries, such as older care recipients, their families, and society. Additionally, Framework (3) concluded that the intrinsic rewards of care work and the altruistic motives of care workers could lead to low or stagnant compensation.
The latter two frameworks addressed different issues. Framework (4) focused on the psychological distress of paid caregivers due to their deep acting and use of intimate parts when providing services to clients. Alternatively, Framework (5) rejected the dichotomy between sentiment (i.e., genuine care motive) and pay. Instead, it suggested that the genuine intrinsic motivation of care workers would persist if the pay were accompanied by trust and appreciation (England, 2005).
Methods
Participants
The inclusion criteria were (1) being a Thai male or female aged 20 years and above; (2) having been caregivers of older adults (aged 60 years and above) in the Bangkok Metropolitan Region (i.e., Bangkok, Nakhon Pathom, Pathum Thani, Nonthaburi, Samut Prakan, and Samut Sakhon) for at least one month; and (3) receiving wage payments and not being biologically related to their older clients. The exclusion criteria were (a) refusing to participate in the study, (b) not signing consent forms and related documents, or (c) voluntarily or involuntarily failing to complete the interview. Unfortunately, one potential male respondent refused to participate in the study.
The participants were live-in (i.e., living in the client’s home) or live-out (i.e., commuting to and from the homes of older clients), freelance/independent or affiliated, and with regular or temporary contracts. Eight out of 37 female participants were affiliated caregivers working under agent companies. The rest (n = 29) were freelancers, out of which 17 participants were previously affiliated with agent companies, and 12 participants never had any prior affiliations.
Research Design and Data Collection
The principal researcher conducted exploratory research with two objectives: to explore work motivation and understand the quality of work life perceived by IPCs in Thailand. The study conducted 37 semi-structured telephone interviews from July to September 2020 (IRB Certificate of Approval No. 075/2563, Study No. 009.1/2563).
The study employed purposive and snowball sampling techniques to recruit participants, who were approached via a caregiver community on Facebook and LINE. However, a few participants introduced their friends or family (i.e., a daughter) to the study. The interviews lasted for approximately 30–60 min, and each participant was compensated 800 THB (21 USD) for the time and effort. Based on the data saturation model (Saunders et al., 2018), the researchers stopped recruiting new participants when the new data repeated previous ones.
Moreover, following the interpretation of the care diamond model, the interview questions were structured to cover the care coordination and interpersonal relationships between the IPCs and the families of older clients. In summary, the interview questions covered the characteristics and care skills, work motivations, factors associated with older clients, preparation and practices during emergencies, desire to apply for advanced training courses, work conditions, and well-being.
Data Analysis
All interviews were audio-recorded and transcribed. The principal researcher applied the thematic analysis method of Strauss and Corbin (1990), as described in the book Social Research Methods (Bryman, 2012). The steps for thematic analysis included (I) open coding, (II) axial coding, and (III) selective coding.
First, the principal researcher reread the research objectives before reading the interview transcripts to align the coding with the research objectives. Second, the researcher wrote down open coding or the concept of each interview finding. Third, she labeled “axial codings” that categorized all open codings in (I) based on contexts, patterns of interaction, causes, and consequences. Fourth, selective coding(s) or the major theme(s) that could reflect the axial codings in (II) and effectively convey the key message of the interviews were created.
The study derived a thematic analysis of work motivation from the participant’s responses to a question regarding work motivation. However, work-life themes were synthesized from a thematic analysis of participants’ characteristics (i.e., personal factors, personality traits, and care skills), work conditions (i.e., workplace conditions and factors associated with older care recipients), and well-being (i.e., overall life satisfaction and work-life satisfaction).
The interview excerpts presented in the paper were labeled with the participants' pseudo name, age, and sex (female). In addition, the Supplemental Material provides the checklist of the COnsolidated criteria for REporting Qualitative research, interview questions, and the codes and explanations for personality traits, work conditions, and well-being.
Results
Descriptive Data of Characteristics and Work Conditions
Characteristics and work conditions of in-home paid caregivers of older adults (n = 37).
Note: n = 37 for most variables, IPC = In-home paid caregiver,
More than half reported that their former agencies placed them in a two-day intensive course prior to working. However, only five participants (13.5%) were certified nurse’s aides, for which they paid approximately 7,000 THB (182 USD) and spent 3–6 months (420 h) for training. Nonetheless, many participants expressed that they could remarkably improve their skills by receiving advice and demonstration from the health professionals they meet when accompanying clients to hospitals.
The care skills of the participants reportedly covered personal care assistance, pressure ulcer management, physical therapy exercise, nasogastric feeding, endotracheal suctioning, insulin injection, and urinary catheterization. Typically, participants with bed-bound clients possessed more advanced care skills than those serving home-bound or independent clients. However, a few participants displayed limited health literacy and could only assist with personal care.
On average, the participants earned 19,590 THB (511 USD) per month, which is higher than the starting salary of a bachelor’s degree graduate in Thailand (i.e., 15,000–18,000 THB). However, a few participants reported receiving approximately 30,000–40,000 THB per month by staying up every hour caring for severely ill clients. Although only four participants reportedly had serious health concerns, such as asthma, low blood pressure, thalassemia, and low back pain (due to previous surgery), many mentioned muscle pain, fatigue, and sleep deprivation since becoming IPCs.
Several participants received money and non-money compliments (e.g., food, clothes, and household essentials) from older clients’ families. In addition, seven participants engaged in part-time jobs or businesses during their free time (e.g., house cleaning, selling goods, or scouting for IPCs) and gained approximately 10%–25% of their wage as IPCs.
Older clients of the participants were 84 years old on average (youngest = 65, oldest = 98). More than 60% were home-bound with cognitive disabilities (32.4%) and bed-bound with severe illnesses (29.4%). Many participants were breadwinners of their families, especially when their husbands or adult children lost their jobs during the COVID-19 pandemic. Several live-in caregiver participants reportedly spent only 1,000–5,000 THB/month (26–130 USD/month) and could save approximately 50%–65% of their monthly income.
In addition, the study found that the common personality traits of the participants were being responsible, having emotional intelligence, having positive attitudes toward care, and being uninterested in workplace socialization (see Supplemental Material). Considering work conditions, anyone doing this job must be patient, sensible, and self-disciplined—looking after them like your father, mother, or relative. And, be honest, so you will never be out of the job. (Jenjira, female, age: 35) They (employers) would look at what you can do, how good your service is, your manners, and how well you can communicate. However, since we have to stay in their house, all we should do is lower our egos and compromise. (Renu, female, age: 47) I chose this job as I avoided working in an organization. I do not like socializing with those people. I enjoy being alone and have autonomy in my work. So, I do not have to argue with colleagues like, “oh, that is not my responsibility, do it yourself!” or “are you talking behind my back, blah blah blah” So, I prefer working alone on my own productive pace. (Somjai, female, age: 43)
Work Motivation
Figure 1 reveals two themes in terms of work motivation (Theme I: This job helps me rise again; Theme II: This job is like a panacea for the mind). Although frequently coexisting, Theme I represented economic improvement, and Theme II involved the desire to search for an emotional anchor. Certain participants who returned to this job reported that they went back to caregiving, because they could not succeed in other jobs. However, a few cited that although they initially accepted this job for money, they eventually established a strong family-like bond with the older clients and their families. Major themes of the work motivations of in-home paid caregivers.
Many found that this job helps them “rise again” from economic hardships such as business bankruptcy, low-wage jobs (i.e., salary of less than 10,000 THB), and high daily expenditures. Despite the high turnover, many participants believed there would always be a high demand for IPCs. The older participants said they would continue working until they could no longer fulfill their duties. In contrast, the younger participants expressed the desire to quit after saving a sufficient amount of money, such as approximately 200,000 THB (5,213 USD). Many younger participants wished to start their businesses or find a job in the formal sector to obtain better welfare benefits that cover themselves and their families. I had never held money in my hand. I owed many debts. Since becoming a caregiver, I could pay off old farm debts. I can negotiate for installment payment. Before that, I did not even have enough money to spend daily; I always had to borrow. I can now support my family, pay debts, and send money to my children and grandchildren. (Pilai, female, age: 48) When working at a company, I can barely save money. Office ladies have to pay for many things, such as transportation, room rent, and many other costs, to socialize with people. We met lots of people, so it was hard to control ourselves. The money was gone to pay for credit cards, holiday trips, shopping, and so on. (Waewta, female, age: 35)
Second, this job could be viewed as a “panacea” for the traumas of past events. Many believed that they had to be strong in front of their older clients, from whom they perceived much suffering from deteriorating health and cognitive impairment. In addition, several participants reported they did not feel like working; they thought they were living with their (new) family. Older clients were perceived as substitutes for their deceased parents or grandparents. Furthermore, many viewed this job as a form of “merit-making.” They felt that their contributions maximized older clients' longevity and health span while helping alleviate the care burden of family caregivers.
I got a master’s degree, so many people asked me why I came to do this job. I just love it. I like doing care work. Also, it is an honest job that can earn me a living and bring happiness to my life. (Noknoi, fem ale, age: 33)
I learned several life lessons from working here. People were born, got old, became sick, and then died. What are the causes of their illness? This job reminds me to eat well and be more careful in life. (Chanta, female, age: 43)
I cannot just only focus on my concerns or my problems. When working, I feel like I am cheering myself up. All my sadness, suffering, and stress were gone at that moment. Besides, seeing my client getting better each day was a blessing. (Siriwan, female, age: 43)
Work Life
Figure 2 reveals three major themes of the work life of IPCs derived from the thematic analysis of their characteristics, work conditions, and well-being. Major themes of the work life of in-home paid caregivers.
Thematic analysis illustration of the work life of in-home paid caregivers.
Note: IPC = In-home paid caregiver, (1) Great contribution, but low recognition and support, (2) Interdependence as an ultimate career goal, (3) Effective training as a key to opportunity and success.
Work-Life Theme (1) “Great Contribution, but Low Recognition and Support”
Despite their professional dedication, many participants continued to feel insecure and undervalued due to the lack of government support and low social recognition for domestic care jobs. For example, the participants reportedly had limited access to social security due to the lack of official registration and accreditation of IPCs. Moreover, several participants also worked other household chores (voluntarily or involuntarily), such as cleaning, cooking, feeding animals, and watering plants. In addition, one participant, who reportedly had to feed a dog and more than 50 cats in an older client’s house, said that her agent company took about 30% of her salary (5,000 from 17,000 THB). We feel inferior working in an informal sector. But, we work very hard. While the office workers could see their families after work, we were unable to do that. Yet, we still got nothing …. Some had to find a lower-paid job in a formal sector to gain better access to social security before returning to work as IPC (Tubtim, female, age: 48). For me, my current work condition is terrible. I feel depressed working here. My employers do not think of me as family. I am here to look after their loved one, but they look at me as if I were their servant. They never appreciated what I did. They think they can call me anytime, 24 hours. They have never asked anything like, “how are you doing?,” “did you eat?” They do not even care how I sleep beside the patient’s bed. My clothes are always in my luggage as they never care to provide a space for my stuff (Choojai, female, age: 43).
Apart from responsibility and perseverance, the participants also preserved the dignity of their profession by reportedly refraining from stealing/pickpocketing and resisting sexual pressure. For the latter, the participants who experienced sexual pressure were reportedly often on their own to avoid becoming sexual victims. For example, two participants reportedly quit the next day because their employers took no action after the IPCs reported being sexually harassed by older male clients. Alternatively, one participant said she mildly threatened to expose the incident and explained to her older male client that her job was to take care of his health and not his genital stimulation. I told him that his children all had respectful jobs, so it would badly affect their careers if someone knew about his behaviors. Finally, he stopped and said, ‘okay, I would not do that again.’ However, I learned that he did that again to other female caregivers who replaced me when I was briefly away (Chanta, female, age: 43).
Work-Life Theme (2): “Interdependence as an Ultimate Career Goal”
Though initially motivated by money, many participants continued working as IPCs because they could depend on the families of older clients through tangible and intangible support. At the same time, many participants were proud of themselves that another person could also depend on them. Nonetheless, many pointed out that the families/employers of older clients played the most vital role in creating or destroying an interdependent relationship. I missed my previous client, a grandma who passed away at 95. I missed her a lot. We hugged and slept in the same bed. We had been very close to each other. I love her. Every morning, she would say, “Yada, you wake up?” and I would say, “No, give me five more minutes.” And she would sing to wake me up. (Yada, female, age: 55). One of my former clients was really good, so I sent my daughter to work there. Their family and relatives were all nice. I am so thankful that they never drew the line. On the contrary, they always expressed gratitude to us for helping them look after their mom. (Chanta, female, age: 43) It is hard to bear another day working with a fussy and unkind employer. So, even if they gave me 25,000 or 30,000 baht, I would not stay. You know, a happy hut is better than a gloomy castle. (Noknoi, female, age: 33)
Work-Life Theme (3): “Effective Training as a Key to Opportunity and Success”
Some of the participants taking care of bed-bound older adults reported wanting to learn more skills to perform specific care, in which home dialysis and colostomy care were frequently mentioned. Although many participants expressed the desire to pursue higher education and training to obtain a higher pay or to find a job at formal care facilities, a few already gave up for several reasons.
First, many participants did not get paid on their days off; thus, they were unlikely to leave their job for a full-time training to be certified nurse’s aides (3−6 months) or licensed practical nurse training (approximately one year). Therefore, the participants said that dividing the courses into short modules that require less number of days to complete would be desirable. As such, they could spend time to find an ad-hoc or day-to-day care job to support their study. Second, given daily workloads and personal financial issues, other participants lacked sufficient time and money to pursue additional education and training. Third, older participants with low levels of Internet literacy said that online learning would be difficult for them. In addition, several participants were concerned about the quality of training provided by private agencies and preferred training organized by university hospitals or public health authorities.
Discussion
As we realize that “domestic work makes all other work possible” (Slaughter, 2016), this study revisits the work motivation and quality of work life of IPCs in Thailand to provide theoretical extensions and policy implications. Despite being in different contexts, nearly all participants and 58% of 302 surveyed domestic care workers in the United States for older adults (Wright et al., 2022) are reportedly the breadwinners of their families.
The relatively good salary compared with those of other professions and without age- or education-specific qualifications, younger and middle-aged individuals in Thailand, particularly women, were motivated to become IPCs for older adults. Moreover, staying at the homes of older clients can help cut several expenditures such as transport cost, food, and accommodation. Furthermore, similar to studies conducted in the United States and Finland (Kusmaul et al., 2020; Ruotsalainen et al., 2020), the participants of the current study perceived that the job had given them a sense of autonomy and competence, as reflected by the perceived high impact of their services on the lives of their clients.
Linkages of work-life themes, existing literature, and policy recommendations.
Note: 1(England, 2005), 2(Kusmaul et al., 2020; Ruotsalainen et al., 2020), 3(Sudore & Covinsky, 2011).
Following Framework (3) (England, 2005) and the work of Singtuen et al. (2018), the current study also finds that the love of doing care work and the bond with older clients have made this job inescapable. Moreover, we further discover that a few of the participants intentionally opted for this job because it fits their solitary lifestyle. However, the findings on the quality of work life mainly agree with Framework (5) (England, 2005), in which money may not unnecessarily eliminate the altruistic motives of paid caregivers but coexist. Furthermore, it could also involve the desire to establish interdependent relationships between IPCs and their employers (i.e., older clients and families). Despite the nerve-wracking day-to-day workload (Shotwell et al., 2019; Sjöberg et al., 2020), the participants said they could endure sleep deprivation and additional work (e.g., household chores) if the salary and relationship with employers meet their expectations.
Nonetheless, the lack of government support and societal appreciation for IPCs in Thailand has weakened the desirability of this job. The study found that other IPCs are alone in their fight to maintain the dignity of their profession, such as avoiding sexual pressure from older male clients. Moreover, although paid caregivers in the United States reportedly suffered from low income, job instability, and poor access to health care (Hoffman & Wallace, 2012), the current findings particularly echo the concern of IPCs regarding poor or limited access to social welfare.
Based on Thailand’s Social Security Act B.E. 2533 (Office of the Council of State, 1990), workers in the formal sector could apply for social security sector 33 (currently working) and sector 39 (formerly working), whereas informal workers can only apply for sector 40, which has the least benefits. All of the participants held social security under sector 39 or 40; however, a few of them know other IPCs who continue to lack social security. Similarly, a quantitative paper based on the National Domestic Workers Alliance survey for 2011–2012 (Wright et al., 2022) found that the majority of domestic adult care workers in the United States (n = 302) received no employer contributions on their payroll taxes (79.9%), social security (84%), compensation (88.9%), and health insurance (95.5%).
According to Miller et al. (2013), IPCs were among the first or primary identifiers of the functional and cognitive declines of older adults. Therefore, improving the quality and quantity of IPC supply should be set higher on the agenda to promote longevity economies and well-being in the “fourth age,” when the majority of older adults are battling frailty and abjection (Higgs & Gilleard, 2017).
In addition, according to the Department of Health Service Support, the Ministry of Public Health of Thailand, registration and licensing have only been available for caregivers working in certified care facilities and have not covered IPCs. Therefore, this study urges the government to promote the recognition of IPCs by providing registration and licensing, responsive incentives and benefits, social and community protection, IPC–family care coordination support, further education and training, and consultation channels.
As implied by the family and private sectors in the care diamond model (Razavi, 2007) and the work-life theme (2) of the study, we suggest that care coordination between the IPCs and the families of older clients should be enhanced through consultation programs, which may be led by government agencies. Previous studies suggested that imposing dyadic interventions to improve the knowledge and skills of family and non-family caregivers (Shaw et al., 2020) could eventually help optimize home care delivery to older adults and improve the well-being of these caregivers (Barnhart et al., 2014).
However, the study found that low health literacy and insufficient training of family caregivers and IPCs were of great concern (Burgdorf et al., 2019; Lindquist et al., 2011; Singtuen et al., 2018; Tamdee et al., 2019). Therefore, “attention to the content of care,” “additional case-specific supervision” (Reckrey, Bollens-Lund, & Ornstein, 2021), and practical job-specific training (Sudore & Covinsky, 2011) are required to provide quality care. Moreover, Bruening et al. (2020) and Maximiano-Barreto et al. (2021) also emphasize that policymakers should consider the families and social environment of caregivers before tailoring support.
Also, the care coordination between IPCs and a comprehensive range of other care providers (e.g., family caregivers, physicians, nurses, and social workers) should be strengthened to promote positive care outcomes (Sterling et al., 2020). In addition, given the difference in preference and level of Internet literacy, the current findings call for multiple formats and settings of job training and supportive consultation networks.
Regarding the limitation of this study, first, we lacked the opportunity to observe the facial or body expressions of the participants during the telephone interviews. Second, the absence of triangulation omits the opportunity to cross-check errors and biases in the responses of the participants. Thus, future research should further explore care coordination among IPCs, the families of older clients, health professionals, and community health volunteers (if applicable) and its impacts on care delivery to older adults.
Supplemental Material
Supplemental Material - Motivation and Quality of Work Life of In-Home Paid Caregivers of Older Adults
Supplemental Material for Motivation and Quality of Work Life of In-Home Paid Caregivers of Older Adults by Kanokwan Tangchitnusorn and Vipan Prachuabmoh in Journal of Applied Gerontology
Footnotes
Acknowledgments
The authors would like to thank all research participants. Also, they would like to acknowledge Mr. Adesorn Guntamaunglee for his help with participant recruitment and audio transcription.
Author Contributions
KT and VP participated in the research design. KT recruited participants, conducted interviews, analyzed data, and drafted the manuscript. KT and VP revised the manuscript draft before submission.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest regarding this article’s research, authorship, and publication.
Funding
This manuscript is based on the research project (Grant No. DNS63056300141), which was partially funded by Chulalongkorn University under the “Grants for Development of New Faculty Staff, Ratchadaphiseksomphot Endowment Fund” from 2020 to 2021.
Ethical Approval
This study was approved by The Research Ethics Review Committee for Research Involving Human Research Participants, Group 1, Chulalongkorn University (Certificate of Approval No. 075/2563, Study No. 009.1/2563).
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References
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