1 Definition of sub-health concept
Some studies believe that the so-called "sub-health" refers to people's low-quality health in terms of physical and mental feelings and their experience between health and disease [2]. Chen divided sub-health into three stages: (1) mild psychosomatic disorders: fatigue, insomnia, loss of appetite, emotional instability and so on. (2) Latent clinical state: Its manifestations can be summarized as: decreased vitality, decreased responsiveness and decreased adaptability. Clinical examination can find that there are near-critical levels of hypertension, hyperglycemia, high blood viscosity and low immunity; (3) "Pre-clinical" state: refers to the state that the patient has been ill but the symptoms are not obvious, and the doctor has not made a clear diagnosis and has not started treatment [3]. Zhao and others believe that sub-health status includes: those who have no clinical symptoms or mild symptoms but have potential pathological information [4]. Liu Baoyan [5] and others put forward the definition of sub-health by exclusion method, that is, a state of discomfort or obvious decline in adaptability without definite disease diagnosis for more than 3 months, or a disease with definite diagnosis but no direct causal relationship with the current discomfort. This definition makes the concept of sub-health more operable.
Based on the viewpoints of various literatures, it can be considered that the sub-health state is mainly manifested in three aspects: insomnia, dizziness, fatigue, drowsiness, fatigue, palpitation and so on; Psychological manifestations are depression, listlessness, memory loss, anxiety and irritability, nervousness and so on. Social adaptation is characterized by indifference, hopelessness, helplessness, loneliness and emptiness.
2. Epidemiology of sub-health state
3 1 ~ 50 years old is the high incidence age of sub-health state, especially 40 ~ 49 years old, accounting for 49.8% of sub-health state. The incidence rate of teachers, medical workers, editors, engineers, technicians and other people engaged in more mental work is significantly higher than that of other high-tech personnel [6]. Zhu Li et al. [7] reported that 30-40 years old is the dangerous age for sub-health of college teachers, among which female students are more severely sub-healthy, and unhappy work, long working hours and lack of physical activities are the risk factors for sub-health of young college teachers. Zhang et al. [8]' s investigation results show that the incidence of sub-health state in northern China is 265438 0.3%. Cai et al. [9] randomly selected 850 people from Guangzhou for a questionnaire survey. The results show that the total incidence of sub-health in this survey is 42. 10%. Multivariate Logistic regression analysis shows that there are nine factors related to sub-health: life stress, education level, frequent drinking of strong tea, sleep situation, work or study stress and interpersonal relationship as risk factors, suggesting that sub-health is related to personal quality, lifestyle and various pressures. Hui Ling et al [10] investigated the sub-health status of residents in a residential area in Wuhan. The results showed that the incidence of sub-health was 79.64%, and several factors such as gender, age, education level, occupation and marital status were selected as independent variables, and the sub-health status was analyzed by stepwise Logistic regression. The results show that gender and occupation are the main influencing factors, and the sub-health status of men is less than that of women, and the OR value is 0.602. Compared with the service industry and other personnel, teachers, civil servants and self-employed people have a higher incidence of sub-health.
Wang Hongyu et al. [1 1] conducted frequency analysis and cluster analysis on 40 symptoms in 378 questionnaires meeting the diagnostic reference standard of sub-health state. The results show that fear of heat, cold, fatigue, mental fatigue and early awakening are the core symptoms; Short and thick eyes, swollen eyes, forgetfulness, dry throat, irritability, lethargy, difficulty in falling asleep, spontaneous sweating, dizziness, lethargy and physical pain are common symptoms of sub-health state.
Wang Jing [12] and others detected the changes of hemorheology and related indexes in 247 sub-health employees. The data show that the whole blood viscosity, plasma viscosity, hematocrit and whole blood reduction viscosity of sub-health workers are obviously higher than the reference values, in which the increase rate of plasma viscosity is 79.7% and hematocrit is 68.4%.
3. Causes of sub-health state
3. 1 The causes of sub-health and stress sub-health are varied and complicated, which can be summarized as the corresponding compensatory response of the body after being stimulated by environment, psychology and physiology, that is, stress response [13]. Psychosocial factors are important sources of stress in modern society. Occupational competition, work pressure, tense pace of life, complicated interpersonal relationships, crowding and loneliness will all cause stress reactions. In addition, the body's own instability and imbalance, such as changes in blood composition, low cardiopulmonary function, environmental pollution, infection, etc., are all important stressors. Stress is a non-specific and fairly general reaction. Its basic reaction is neuroendocrine reaction represented by hypothalamus-pituitary-adrenocortical hormone axis (HPA) excitation [13]. Research [14, 15] shows that mental stress can lead to the imbalance of neuroendocrine system. Wu et al. [16] research shows that the level of occupational tasks and individual stress response are positively correlated with sub-health status; The levels of 5- hydroxytryptamine and norepinephrine in the brain of teachers in sub-health group are higher than those in normal group.
In addition, the activation of sympathetic-adrenal follower and hypothalamus-pituitary-adrenocortical hormone axis is also related to hypertension. The continuous increase of glucocorticoid also causes metabolic changes, which leads to the increase of blood cholesterol and the retention of sodium and water in vascular smooth muscle cells. These factors may promote hypertension and atherosclerosis.
The immune system is an important part of the stress system, and the neuroendocrine changes during stress play an important role in regulating the immune system, because the most obvious hormones during stress are glucocorticoid and catecholamine, both of which have inhibitory effects on the immune system. In patients with chronic fatigue syndrome (CFS), the surface activation markers of T lymphocytes increased [17], especially the surface markers of CD8+T lymphocytes increased significantly [18], and the function of natural killer cells (NK) decreased [19]. The mRNA expression of transforming growth factor -β 1 (TGF-β 1) is weakened [20]. Overexpression of cytokines such as interferon-γ (IFN-γ) and interleukin -6(IL-6) induces infection, which is considered to be an important cause of fatigue, myalgia, memory loss and low fever in CFS patients [20
3.2 Sub-health and persistent stress reactions of hemorheology, such as excessive tension, excitement, depression, anxiety, anger, etc. , is one of the important reasons for the increase of blood viscosity. The increase of catecholamine and the activation of spleen α -receptor lead to the increase of red blood cell excretion, hematocrit and blood viscosity [23], which in turn leads to blood circulation disorder, increase of circulation resistance, decrease of blood flow velocity, decrease of perfusion of tissues or organs, especially microcirculation, and ischemia, hypoxia and metabolic disorder of tissues or organs [24]. This series of abnormal changes is the basis of pathological changes such as degeneration, edema, inflammation, necrosis, sclerosis or thrombosis, which occurs before clinical symptoms or signs, that is, the transitional stage between health and disease-sub-health. Therefore, it is reasonable to think that abnormal hemorheology is one of the main factors leading to sub-health.
4 evaluation of sub-health status
From the concept of sub-health, its two main characteristics are discomfort and decreased ability, which can include at least four situations: (1) the persistent process of chronic diseases with hidden progress and no obvious clinical manifestations; (2) Impaired immune function and unstable endocrine system lead to organ dysfunction of corresponding and related systems; (3) The recessive infection process of some diseases; (4) Psychological disorders that cannot be diagnosed as diseases [4]. Therefore, there are four main symptoms: muscle symptoms, gastrointestinal symptoms, cardiovascular symptoms and mental symptoms. At present, the evaluation of sub-health status is mainly based on questionnaire survey, and researchers mostly use self-made questionnaires, but there are many kinds of questions and there is no unified judgment standard.
Chen Qingshan et al. [25] used Delphi method to evaluate the diagnostic criteria of sub-health, and considered that the sub-health criteria were 1 year with symptoms above 1 month. Liu Baoyan et al. formulated a questionnaire on basic symptoms of sub-health TCM [26], which consists of six modules: general information, physical condition, living condition, energy condition, personal endowment and social environment condition. The Cronbach α reliability of the questionnaire is 0.9309, and the results of factor analysis also confirm the theoretical assumption. It can be summarized as seven sub-health types: psychological sub-health, fatigue sub-health, sleep sub-health, gastrointestinal sub-health, body sub-health, pain sub-health and other sub-health. Hu Fang [27] used Symptom Checklist 90 (SCL-90) to conduct psychological investigation and evaluate sub-health status; Lv Caizhao and others [28] designed a sub-health questionnaire with reference to SCL-90. Li Yanhua et al. [29] used Cornell Medical Index (CMI) to fill out the health questionnaire to investigate the sub-health status. CMI judgment method: CMI questionnaire is divided into 18 parts, each part is arranged in English alphabetical order, *** 195 questions. If you answer "Yes" to each question, you will get 1 point; if you answer "No", you will get 0 point. All items are added up to get the total score of CMI. Male total score ≥35, m-r ≥15; The total score of female is ≥40, and M-R is ≥ 20. Those who meet this standard are people with physical and psychological barriers selected from the normal population.
5 outlook
The concept of sub-health fully embodies modern people's new healthy thinking of paying attention to health and preventing problems before they happen. At present, the research on chronic fatigue syndrome (CFS) abroad is extensive, and there are clear diagnostic criteria. From the domestic literature, the concept of sub-health is much broader than CFS. Although sub-health is related to occupational stress, work stress and unhealthy lifestyle, its mechanism has not been confirmed.
At present, there are many investigations on sub-health status of people, but most of them use self-made questionnaires and judgment criteria, which makes the research results not comparable. In the diagnosis of sub-health status, objective indicators are rarely used, and the detection rate of sub-health status is quite different. Although it is no stranger to the concept of sub-health, it is difficult to accurately define and exclude diseases in practical application. In the study of sub-health, it should be based on the association with clinical diseases that may develop in the future, so as to achieve the purpose of preventing diseases. The changes of various biomarkers in sub-health state are of great significance for early diagnosis, classification and prediction of diseases, including physiological, biochemical, endocrine and immune indexes.