After removing duplicates, a total of 6437 English articles and 6169 Chinese articles were identified through database searches. Following title and abstract screening, 33 English studies and 87 Chinese studies remained. Full-text selection further reduced the number to 6 English articles and 25 Chinese articles. The detailed information of the included paper was provided in Appendix 2. The selection process was illustrated in Figs. 1 and 2 of the PRISMA flow charts.

PRISMA flow diagram (English database)

PRISMA flow diagram (Chinese database)

During full-text review, the 31 included papers were primarily divided into two categories: focusing on general definitions of HRQoL and frameworks of HRQoL. Among them, 14 papers focus on providing a general definition of HRQoL, 11 papers delve into HRQoL frameworks, while 6 papers contain information pertaining to both the general definition and the framework. Additionally, a distinction was made between studies based on TCM perspectives and those using the perspective of modern medicine (MM). The categorization of each paper was provided in Appendix 2.

Based on the included papers focusing on general definition, we found that these papers introduced the foundational theory of TCM, which not only supplied potential corroborative evidence for TCM framework but also laid the foundation upon which TCM framework was developed.

The notion of 'Yin Yang' theory emerged most prominently as the foundational principle of TCM [17,18,19,20,21,22,23,24,25,26]. Additionally, the notion of 'Ping ren' [21, 22, 27,28,29,30,31,32] and 'He' [33, 34] were also highlighted as the basis principle of TCM. The meanings of these principles are as follows. According to TCM, everything in the universe can be divided into two opposite but interconnected forces: Yin and Yang. For instance, the earth represents Yin, while the sky represents Yang, reflecting a universal concept. Specifically for human, the spirit is considered Yin, while the body is considered Yang. Health is believed to arise from the balance between Yin and Yang, both internally and within the surrounding environment. Additionally, individuals' health is influenced by the balance between different materials and the harmony between their 'Yin essence' and 'Yang spirit' [20].

Under the guidance of the general 'Yin Yang' theory, the most recognized definition of health is 'Ping ren' [21, 22, 27,28,29,30,31,32], which refers to a person in a healthy state with harmonious blood circulation, calm breathing, and steady pulse. TCM practitioners commonly view these indicators as signs of good health [19, 22, 24]. The concept of 'Yin Yang' aligns with another related phrase, 'He,' which emphasizes ‘harmony’ as the essence of health. 'He' represents the harmony between ‘Qi’ (energy in the broadest sense possible) and blood (important indicators of physical health in TCM) and the harmony of the spirit (associated with mental and emotional well-being). Both 'Yin Yang' and 'He' reflect characteristic philosophical thoughts in Chinese traditional culture [26, 30].

In the identified studies, the three most commonly used concepts under the 'Yin Yang' theory for defining and measuring health were as follows: ‘Xing Shen Tong Yi'(形神统一) [17,18,19,20, 22, 25,26,27, 31, 33, 35,36,37], 'Tian Ren He Yi'(天人合一) [17, 19, 20, 22, 25,26,27,28, 35, 37, 38] and 'Qi Qing'(七情) [17, 25, 27, 36, 37].

'Xing Shen Tong Yi' means the unity of body and spirit, which can be specifically divided into two domains: 'xing' and 'shen'. The 'xing' domain refers to the body structure, such as the viscera, meridians, essence, blood, muscles, limbs, and bones [19], focusing on physical health. By summarizing the included studies, the following facets were identified: stamina, sleep, appetite and digestion, complexion, stool, mobility, self-care, discomfort, pain, urination, voice, and constitution. These indicators can be used to confirm whether a person is physically healthy or not.

The 'Shen' domain has a broader meaning, which refers to both the gods of nature (i.e. natural phenomena and laws) and the mental state of the human body (i.e. emotions, will, personality, memory, and perception) [22]. By summarizing the included studies, the following facets were identified: thinking, verbal expression, consciousness, spirit of the eyes, memory, concentration, fatigue, confidence, and satisfaction. 'Xing Shen Tong Yi' also reflects the basic view of holism in TCM that people are an organic integrity, and that the body and mind are closely interdependent [20].

TCM emphasizes the unity of the human body and its relationship with the external environment [17, 27]. 'Tian Ren He Yi' emphasizes the harmony between humans and environment [17, 20, 35], which can be divided into two domains: natural environment and social environment.

In the 'natural environment' domain, TCM highlights the interconnectedness between humans and nature. Any changes or movements in nature will directly or indirectly affect the human body, such as seasonal climate changes, regional differences, leading to physiological discomfort or pathological changes [17]. This domain encompasses two facets: climate adaptation and adjustment, as well as dwelling conditions.

In the 'social environment' domain, TCM recognizes that humans are not only part of nature but also part of society. Health is influenced by various social factors, including political, economic, cultural, marriage, and interpersonal aspects. These factors will affect people's emotional changes, which can further impact the health of human. Common facets in this domain include socialization (e.g., communication, sex life, and loneliness), family (including family relationships, support, and conflicts), work (including relationships with colleagues and work performance), and economic conditions [39].

The concept of 'Tian Ren He Yi' is the direct embodiment of the relationship between human and environment. People's adaptation to the external environment is also the external embodiment of human health. Maintaining harmony between humans and the natural environment is of great importance [19, 20, 35].

In TCM, the concept of 'Qi Qing' refers to the seven basic emotions: joy, anger, worry, pensiveness, grief, fear, and anxiety [17]. According to TCM, these emotions are closely linked to the five internal organs to our body: heart, liver, spleen, lung, and kidney [36, 37]. Each emotion corresponds to a specific organ, and when emotions become intense or unstable, they can disrupt the balance of ‘Qi’ (energy in the broadest sense possible) and blood, leading to physical problems. For example, anger affects the liver, joy affects the heart, pensiveness affects the spleen, worry affects the lung, and fear affects the kidney [17]. Therefore, maintaining emotional stability is essential for overall health and proper organ functioning.

Additionally, some of the definitions of HRQoL mentioned in the eligible studies may not fall within the purview of 'Yin Yang'. For instance, Confucianism emphasizes positive attitude and family relationships [18, 22], as well as the concept of ‘moderation’ to maintain a healthy state [22]. Taoism highlights conforming to nature and maintaining peace of mind without overthinking [22, 30, 31, 40]. Buddhism places importance on virtue and the theory of karma, where good behavior leads to positive outcomes, including physical health and mental satisfaction [18, 22].

From MM's perspective, two definitions were discussed. Firstly, one study adopted the definition from 'Ci Hai,' an authoritative Chinese dictionary [35]: ‘The state of well-developed organs and systems, normal functions, strong physique, full of energy, and high labor efficiency, which are usually measured through physical examination and various physiological indicators’ [41]. Secondly, most studies on HRQoL were based on the World Health Organization's (WHO) definition of ‘health’ [10, 18, 19]: ‘health is a complete state of physical, mental, and social well-being, not simply the absence of disease or infirmity’ [42]. The WHO definition of ‘health’ was not only used in defining HRQoL but also incorporated into the development of HRQoL instruments. Most studies defined HRQoL using the following three concepts: physical health, mental health, and social health, with some suggesting modifications. In the Chinese context, the concept of 'environment' such as dwelling conditions and changes in climate may be added [18, 21,22,23, 38]. The detailed framework results are shown in Figs. 3 and 4.

Traditional Chinese medicine framework

Modern medicine framework

The concept of 'physical health' can be divided into two domains: 'physical function' and 'physical senses'. In the domain of ‘physical function’, researchers focus on basic functions of body, such as appetite, sleep, mobility, daily activities, self-care, vision, hearing, body constitution, physical exercise, recreational activities, and heavy physical work. In the domain of ‘physical senses’, attention is given to discomfort, pain, and disease, reflected in facets such as pain, fatigue or tiredness, energy or vitality, body weight, dependence on medication, discomfort, complexion, body strength, and family medical history.

'Mental health' consists of three domains: emotional experiences, mind-frame, and cognitive functions. In the domain of ‘emotional experiences’, common facets include depression, stress, anxiety, regularity in daily life, sex life, loneliness, worry, anger, fear, happy mood, no worry, and no pressure. The ‘mind-frame’ domain encompasses facets like self-confidence, morality, positive attitude, peace, breadth of mind, and sense of life satisfaction. Lastly, the ‘cognitive function’ domain includes facets such as memory, concentration ability, sharp mind, clear mind, decision-making ability, and thinking ability.

'Social health' can be divided into three domains: interpersonal relationships, work or school, and economic condition. ‘Interpersonal relationships’ emphasize the ability to communication with others and the adaptability to the environment. It includes the following facets: social interactions, good relationships and communications with others (e.g. friends, family and colleagues), social support, adaptability to social environment and burdens to others. The ‘work or school’ domain concerns task completion and performance in studies or job. Additionally, ‘economic conditions’ are also a crucial component of overall mental health.

Apart from the three fundamental WHO health concepts, namely physical, mental, and social health, the concept of 'environment' has also been recognized as an important factor in the included studies [18, 21,22,23, 38]. This domain encompasses the ability to adapt to changes in weather and living conditions.

Both TCM and MM break down their concepts of HRQoL into 'domains', as depicted in Figs. 3 and 4. These domains demonstrate significant overlap between TCM and MM perspectives. They encompass intrapersonal (such as physical and emotional aspects) and interpersonal domains (such as relationships and work).

When these domains are operationalized into survey questions, the resulting 'facets' further reveal the similarities between TCM and MM. Figure 5 illustrates that many facets share common wording. Among the 59 facets identified, 28 were addressed in both TCM and MM, 9 were specific to TCM, and 22 were specific to MM. Among the shared facets, we found that 'appetite', 'sleep' and 'energy' were the most frequently mentioned facets in both frameworks.

Intersection diagram of the facets of TCM and the MM frameworks