This nation-wide cross-sectional study illustrated that approximately 52.88% participants reported complaint of SHS among 22,897 Chinese people. Two dimensions of personality traits, i.e., agreeableness and conscientiousness, might protect individuals against SHS. Persons with neuroticism trait had a higher likelihood of developing SHS. Moreover, perceived stress played a key role in mediating the relationship between personality traits and SHS.
Studies on SHS prevalence commonly presented inconsistent results due to the heterogeneities of respondents and SHS measurements. There are more than five SHS scales that have been reported in China investigations, such as the Suboptimal Health Status Questionnaire-25 (SHSQ-25), the Multidimensional Sub-health Questionnaire of Adolescents (MSQA), the Sub-health Measurement Scale Version 1.0 (SHMS V1.0), the Chinese Sub-health State Evaluation Scale (CSHES), and the Sub-Health Self-Rating Scale (SSS) [31–33]. Of these scales, SHSQ-25 is the most widely used worldwide, including Eastern Asian, African, Oceanian, and European.
Two studies conducted with SHSQ-25 scale reported a lower level of SHS in college students (20.98%) and a higher one in general adult population (69.46%) in China [34, 35]. In the current study, we observed a prevalence of 52.88% across 148 cities of China. It is need to be noted that we used a simplified form of SHSQ-25. This may introduce heterogeneity of methodology across these studies even though SHSQ-SF has been validated in both northern and southern populations in China. Moreover, this study included a large number of younger participants and college students, which might lead to an underestimation compared to the measurements within middle-aged and elderly population [35].
Psychological factors play a crucial role in the development of SHS, and psychological symptom is always one of the key dimensions of SHS measurement [10]. Studies have identified the impact of depression and anxiety on the health issues of college students [34]. Personality is also one of the important contributors to quality of life and health conditions [36]. With regard to the direct effects of personality traits on SHS, the current results suggested that participants with higher levels of agreeableness and conscientiousness are more likely to experience optimal health. This finding is consistent with a previous survey in a diverse sample, which found that agreeableness and conscientiousness were the best predictors of health behavior [37].
It has been shown that agreeableness is negatively related to risk-taking behavior [37]. Given that agreeableness has an inverse association with hostility [38], the finding was in line with earlier researches that linked hostility to negative health habits [37, 39]. Negative patterns of lifestyles increased the risk of somatic diseases among individuals with hostility trait, supporting that positive patterns of habits decrease the risk of SHS among persons with higher agreeableness. In addition, the personality of conscientiousness improves health status through healthy behavior management, i.e., maintaining healthy behavior patterns, and avoiding the harmful ones [40].
Our results demonstrated that participants with personality of neuroticism were more likely to develop SHS, supporting the previous findings that emotional stability is a strong contributor to perceived health condition [36, 41]. Individuals with a tendency of neuroticism (i.e., low emotional stability) experience more negative affections and poorer emotional functions [42], which lead to perceived unhealthy symptoms and adverse outcomes [36]. Furthermore, these persons tend to adaptive dysfunction when confronted with perceived stress [36], making them more vulnerable to poor health condition.
We did not find the direct effect of extraversion on SHS. Although some studies demonstrated a significant relationship between extraversion and quality of life in adult population [43], the others conducted in pediatric samples reported either non-significant or weak results [41, 44]. Persons with openness have a propensity to think and behave in nonconforming ways, which may create diversity in their response to health issues. Although the relationship between openness and perceived health condition has not been confirmed [45, 46], we observed that individuals with openness personality had a higher prevalence of SHS.
An individual’s susceptibility to psychological and physical disorders associated with chronic stress exposure, e.g., cardiovascular and infectious diseases, could be predicted by their reactivity to psychosocial stressor. Personality is one of important psychological factors associated with both stress resilience and health outcomes. An understanding of how personality traits influence responses to stress may shed light upon individual differences in susceptibility to chronic stress-linked diseases. Previous studies have suggested that personality traits can modulate responses to perceived stress due to the different effects of distinct traits on the separate components of stress response [47–49]. Stress exposure activates the production of hormonal, as well as cardiovascular and emotional responses [48]. Positive personality traits (e.g., extraversion, agreeableness, conscientiousness, and openness) largely protect against hormonal responses to stress, whereas negative traits (e.g., neuroticism) inversely predict cardiovascular responses [49]. In other words, individuals with high extraversion or openness may be more resilient to negative environmental stimuli and stress-related symptoms. For agreeableness and conscientiousness, the tendency to closely interpersonal and social relationships may protect against excessive stress responses. In addition, combined with the current finding that perceived stress can positively predict the occurrence of SHS, high level of neuroticism may identify individuals at elevated risk for chronic stress-related diseases.
Notably, we identified the mediating effect of perceived stress on the relationship between personality traits and SHS. The mature personality (i.e., extraversion, agreeableness, conscientiousness, or openness) can function as an internal resource which helps people in dealing with various stressors and other psychological distress, thereby playing favorably into their health status. Conversely, the personality of neuroticism may expose people to poor stress adjustment and emotional functioning, thus adversely affecting health conditions.
It is understood that women are more likely to experience psychological distress and neuropsychiatric disorders [26, 50]. Our stratified analysis also revealed a higher level of SHS among women, indicating that women are more prone to both mental problems and SHS due to the differences in physiological and psychological characteristics [51]. Furthermore, the differences in lifestyles between men and women, as well as their pursuit of physical activities, are closely relevant to their mental and physical well-being [52, 53].
Regarding the effects of the covariates, our finding demonstrated that age was one of the important determinants of SHS and perceived stress, in which older participants experienced more SHS and less stress than the younger ones. Consistent with the research conducted within another Chinese resident sample [54], the key factor is a gradual decrease in physical fitness and energy in elderly people. In term of marriage status, being divorced or widowed was significant contributor to SHS and stress. This evidenced the findings that poor marital status was statistically associated with psychological distress and poor health status [55]. With regard to the BMI classifications, our study also showed that the risk of SHS and stress among normal participants is lower than that among thin participants. It has been shown that an underweight status is associated with psychiatric disorders and higher health risks[56, 57], which supports the speculation that reasonable eating habits contribute to alleviation of health issues.
Limitations
This study had several limitations that commonly exist in population-based cross-sectional survey. Firstly, we could not demonstrate the causal relationship between personality traits, stress, and SHS due to the lack of chronological evidence. Secondly, all the data were collected by self-reported questionnaires, which might lead to potential information bias. Thirdly, although the levels of stress and SHS were assessed by standardized questionnaires, these measurements were not equal to clinical diagnoses.
To the best of our knowledge, this study is the first investigation on the relationship between personality traits, perceived stress, and SHS among representative Chinese populations, by covering a broad age range and including different minorities and regions using data from a large-scale cross-sectional survey.