DOI: https://doi.org/10.21203/rs.3.rs-1542097/v1
This study analyzed the mediating effects of shoulder pain, shoulder disability, and depression on the relationship between stress and health-related quality of life among middle-aged women using a serial mediation model. Data on stress, health-related quality of life, shoulder pain, shoulder disability, and depression were collected from women aged 35–64 years living in Seoul, South Korea, from May 13 to 23, 2021, using a self-reported, structured survey. SPSS PROCESS macro (Model 6) and serial mediation analysis were then used to analyze the relationship between stress and health-related quality of life among participants, with shoulder pain, shoulder disability, and depression as mediators. The results indicate that stress had a statistically direct impact on health-related quality of life. In the serial mediation analysis, shoulder pain, shoulder disability, and depression were found to be statistically significant, thus affecting the relationship between stress and health-related quality of life, with an explanatory power of 33%. Therefore, the relationship between stress and health-related quality of life was partially mediated by these variables. Thus, this study suggests the need for healthcare workers to develop methods, such as exercise intervention programs based on various degrees and types of physical activity, to improve health-related quality of life and reduce stress caused by shoulder pain, shoulder disability, and depression among middle-aged women.
Shoulder pain is the third most common musculoskeletal complaint among adults, with a lifetime incidence of ≥ 60% [1, 2]. It was found to persist for ≥ 12 months after the first onset in ≥ 60% of participants [3, 4]. Furthermore, it often becomes a chronic condition, making life difficult and uncomfortable. It also causes functional impairment because of the degenerative changes in tissues and reduces patients’ health-related quality of life [5].
Recently, the prevalence of shoulder pain has been observed in people in their 30s and more commonly in those over 40 years. Several diseases, such as adhesive capsulitis, rotator cuff tendinopathy, glenohumeral osteoarthritis, and neurological and vascular diseases, cause shoulder joint problems. In general, women have lower muscle strength and athletic ability than men, especially because the relaxation of their muscles is affected by female hormones, thus making them more prone to musculoskeletal diseases, including shoulder pain [6–8].
Shoulder pain and disability lower the quality of life [9, 10]. An individual’s assessment of satisfaction with the physical, mental, social, and psychological aspects of life is defined as the quality of life [11]. Assessing health-related quality of life to prevent diseases and promote health has gained increased attention in health-related research and practice [12].
Previous studies have reported a significant correlation between women and shoulder pain; however, such disabilities have not been fully addressed [13–16]. Specifically, few studies have focused on the relationship between shoulder pain and disability among middle-aged Korean women. Therefore, it is necessary to understand the relationship between shoulder pain, shoulder disability, and health-related quality of life in middle-aged Korean women.
A previous study reported that living with chronic pain correlates with and causes psychological stress [17]; therefore, people who have had negative experiences in life have a high risk of developing chronic musculoskeletal pain [18, 19]. In particular, the degree of perceived pain is high in older people and in those with higher stress levels [20]. Therefore, it is necessary to identify whether stress in middle-aged Korean women directly affects shoulder pain and analyze how this relationship affects health-related quality of life.
Previous studies have shown that perceived stress is a known risk factor for chronic shoulder pain [21, 22] and that stress negatively affects quality of life [23]. Limited physical function [24] and depression [25] have been reported to lower quality of life. Furthermore, depression is more common in patients with musculoskeletal disease, especially among those who find it difficult to perform daily activities [24]. Therefore, this study investigated the relationship between stress and shoulder pain, shoulder pain and disability, shoulder disability and depression, and depression and health-related quality of life.
Based on previous research, this study identified the relationship between stress and health-related quality of life in middle-aged women and proposed a serial multiple mediation model to understand this relationship. It further investigated how stress directly and indirectly affects health-related quality of life through mediators such as shoulder pain, shoulder disability, and depression. When these predicted relationships were determined, we validated the serial multiple mediation model to determine the extent to which each variable affected the others.
This cross-sectional survey examined the relationship between stress and health-related quality of life in middle-aged women. Data were collected from 578 women aged 35–64 years, living in Seoul, South Korea. After considering the dropout rate, 565 participants were included in this study, which ensured an appropriate sample size. Data were collected for the period May 13–23, 2021. The selection criteria for the study were as follows: 1) women aged ≥ 35 years, and 2) ability to communicate and complete a self-report survey. The surveys were directly distributed to participants who provided written consent after being informed of the purpose of the study. In principle, the participants completed the questionnaire independently—they were supported by the research staff only if they needed assistance.
The self-reported Patient Health Questionnaire (PHQ)-9, used in screening for depression, was developed by Kroenke et al. [26], and the Korean version, adapted by Park et al. [27], was adapted for this study. It comprises nine items corresponding to the diagnostic criteria for major depression disorder based on the Diagnostic and Statistical Manual of Mental Disorders IV. The PHQ-9 evaluates the frequency of these symptoms over a two-week period. The response of each tool was evaluated on a 4-point Likert scale as follows: 0 for “never,” 1 for “a few days,” 2 for “more than one week,” and 3 for “almost every day.” Kroenke et al. [26] used a score ranging from 0 to 27 points, with four break points of the PHQ-9 that divide the level of depression into five groups according to severity of symptoms (minimal, 0–4; mild, 5–9; moderate, 10–14; moderate-to-severe, 15–19; and severe, 20 or more). However, Park et al. [27] suggested that depressive disorders can be suspected when the total PHQ-9 score is > 5 points; their study [27] had a Cronbach's alpha of 0.81, whereas the current study had a Cronbach’s alpha of 0.85, indicating higher reliability.
The shoulder pain and disability index was developed by Roach et al. [28] to evaluate the degree of pain and disability and adapted by Seo et al. [29]. It comprises 13 questions and is divided into two supplementary scales that include five questions in the pain subscale to evaluate the degree of pain and eight questions in the function/disability subscale to evaluate the degree of upper limb disability when performing different activities of daily living. A total of 13 items were evaluated on a 10-point Likert scale, with 0 indicating no pain and 10 indicating very severe pain. The results of each tool were converted to a 100-point scale. The higher the score obtained using this tool, the greater is the degree of shoulder pain, damage, and disability. The Cronbach’s alpha in this study was 0.94, indicating high reliability.
The extent to which an individual perceived a specific stressful condition was measured. The Korean Perceived Stress Scale (PSS) was used to measure perceived stress, as adapted by Lee et al. [30] from the PSS developed by Cohen et al. [31]. The tool comprises 10 items that are assessed using a 5-point Likert scale ranging from never (0 points) to very often (4 points). In Lee et al. [30], the Cronbach’s alpha of this tool was 0.88, whereas it was 0.96 in this study, indicating higher reliability. The total points ranged from 0 to 40, where 0–13 indicated low-level stress, 14–26 indicated normal-level stress, and 27–40 indicated high-level stress.
The 12-Item Short Form Health Survey (SF-12) developed for the Medical Outcomes Study by Ware et al. [32] was used to evaluate health-related quality of life in this study. The tool was divided into eight sub-regions for two main parts: a physical component summary (PCS-12) and a mental component summary (MCS-12). It comprises 12 items, and the score of each sub-region was converted into a range of 0–100 points, regardless of the number of items, according to the specified calculation method of SF-12. A higher score indicates a higher quality of life. The SF-12 is often used to assess quality of life in relation to health, and its reliability and validity have been proven for all ages [33]. The Cronbach’s alpha was 0.86, indicating high reliability.
This study was conducted in accordance with the principles of the WMA Declaration of Helsinki and the study plan and process were approved by the Clinical Ethics Committee of Daejeon University. Written consent was obtained from all participants following a detailed explanation of the purpose and method of the study, before beginning the survey. Study participation was voluntary, and participants could withdraw at any given time; the collected data were used for research purposes only. The guarantee of anonymity and autonomy of participants was described. The survey data were stored in a secure cabinet.
All study data were processed using SPSS for descriptive statistics and correlation analyses. Hayes’s PROCESS macro (Model 6) was used to verify the mediating effect of shoulder pain, shoulder disability, and depression on the relationship between stress and health-related quality of life. In serial mediation, mediating factors (shoulder pain, shoulder disability, and depression) are expected to directly and indirectly affect health-related quality of life. The serial mediation model helps identify the precedence between the three mediating variables in the relationship between stress and health-related quality of life. In this model, the first mediating variable (shoulder pain) sequentially affected the second mediating variable (shoulder disability), which in turn affected the third mediating variable (depression). Bootstrapping of the SPSS PROCESS macro was used to test the mediating effects in this study [34]. Using random sampling, 10,000 samples were generated and a 95% bias-corrected confidence interval (BC CI) was employed to analyze the mediating effects [35]. If the 95% CI did not cover zero, the effect was considered significant.
The general characteristics of the participants are presented in Table 1. Of the 589 participants who answered the survey, 565 were included in the analysis, excluding incomplete responses and those who dropped out of the study (response rate: 95.9%). All the women (N = 565) were aged 35–63 years, with an average age of 42.15 (6.37). The majority were married (72.7%), and in terms of education, 80.2% possessed a college degree or higher. As for regular exercise, 52.2% responded that they did not exercise regularly and 47.8% responded that they did. Furthermore, 96.8% of the participants were non-smokers and 53.1% did not consume alcohol. Regarding their financial situation, 83.2% were in the middle or higher income class. The average working hours for the participants were 7.08 (2.77) hours per day, and the average sitting hours during work were approximately 4.06 (2.90) hours. Among the participants, 64.2% had no chronic diseases. Depression levels measured using the PHQ-9 showed that minimal depression was the most common (39.6%), followed by mild (35.4%).
| Variable | N (%) | Mean (SD) |
|---|---|---|
| Mean Age (years) (range) | 42.15 (6.37) (35–63) | |
| Marital status | ||
| Single | 141 (25.0) | |
| Married | 411 (72.7) | |
| Divorced & widowed | 13 (2.3) | |
| Education | ||
| ≥Middle school | 112 (19.8) | |
| College | 453 (80.2) | |
| Exercise | ||
| Yes | 270 (47.8) | |
| No | 295 (52.2) | |
| Smoking | ||
| Yes | 18 (3.2) | |
| No | 547 (96.8) | |
| Alcohol | ||
| Yes | 265 (46.9) | |
| No | 300 (53.1) | |
| Economic status | ||
| ≥Middle | 470 (83.2) | |
| Low | 95 (16.8) | |
| Sitting hours during work | 4.06 (2.90) | |
| Working hours per day | 7.08 (2.77) | |
| Chronic condition | ||
| Without | 363 (64.2) | |
| With | 202 (35.8) | |
| Depression | ||
| Minimal | 224 (39.6) | |
| Mild | 200 (35.4) | |
| Moderate | 92 (16.3) | |
| Moderate-to-severe | 39 (6.9) | |
| Severe | 10 (1.8) |
As shown in Table 2, the overall average score for health-related quality of life was 66.28 (10.00), the average score obtained using PCS-12 was 65.28 (10.09), and MCS-12 was 67.15 (11.88). The average score for depression was 6.73 (5.14), which was ≥ 5 points according to the overall average, suggesting a depressive disability. The average stress score was 18.99 (5.47) points, which is normal. The average score for shoulder pain was 42.68 (25.06) out of 100, and the average score for shoulder disability was 26.82 (23.54) out of 100.
| Variables | Min–Max | Mean (SD) |
|---|---|---|
| Health-related quality of life | 25–91.07 | 66.28 (10.00) |
| PCS | 23.08–88.46 | 65.28 (10.09) |
| MCS | 20–100 | 67.15 (11.88) |
| Depression | 0–27 | 6.73 (5.14) |
| Stress | 4–38 | 18.99 (5.47) |
| Shoulder pain | 0–100 | 42.68 (25.06) |
| Shoulder disability | 0–100 | 26.82 (23.54) |
| Note. SD, standard deviation; PCS, physical component score; MCS, mental component score. | ||
The results obtained after analyzing the correlations between the variables are presented in Table 3. Health-related quality of life was found to have a negative correlation with stress (r = − 0.001, p = 0.984), depression (r = − 0.261, p < 0.001), shoulder pain (r = − 0.103, p = 0.015), and shoulder disability (r = − 0.234, p < 0.001). Thus, the higher the stress, the worse the depression; the more severe the shoulder pain and disability, the lower the health-related quality of life. Stress positively correlated with depression (r = 0.589, p < 0.001), shoulder pain (r = 0.221, p < 0.001), and shoulder disability (r = 0.228, p = 0.004). Depression was positively correlated with shoulder pain (r = 0.357, p < 0.001) and shoulder disability (r = 0.366, p < 0.001). A positive correlation was found between shoulder pain and disability (r = 0.694; p < 0.001). Thus, the higher the stress, the worse the shoulder pain and disability and the higher the depression level. Moreover, when shoulder pain and shoulder disability were severe, the depression level was also high, and the worse the shoulder pain, the higher the shoulder disability.
| Health-related quality of life | Stress | Depression | Shoulder pain | Shoulder disability | |
|---|---|---|---|---|---|
| Health-related quality of life | - | ||||
| Stress | −.249(< .001) | - | |||
| Depression | −.261(< .001) | .589 (< .001) | - | ||
| Shoulder pain | −.103(.015) | .221 (< .001) | .357 (< .001) | - | |
| Shoulder disability | −.234(< 0.001) | .228 (.004) | .366 (< .001) | .694 (< .001) | - |
A serial multiple mediation model was developed using Hayes’s SPSS PROCESS macro (Model 6; Fig. 1). Table 4 illustrates the findings of the tested model and how shoulder pain, shoulder disability, and depression mediate the relationship between stress and health-related quality of life in middle-aged women. Notably, a significant total effect (B = − 0.4408, SE = 0.0773, t = − 5.7020, p < 0.001) and direct effect (B = − 0.2598, SE = 0.0934, t = − 2.7816, p = 0.0056) of stress were found on the quality of life. The impact of stress on health-related quality of life was reduced when shoulder pain, shoulder disability, and depression were removed but became significant when they were added to the model as mediators. The effect of the serial multiple mediation model was found to be statistically significant in predicting health-related quality of life based on shoulder pain, shoulder disability, and depression, and the explanatory power of the variables for quality of life was 33% (R2 = 0.30, F = 16.671, p < 0.001).
The bootstrapped indirect effect of stress on quality of life via shoulder pain, shoulder disability, and depression was significant (B = − 0.1809, SE = 0.0652, 95% BC CI [− 0.3140–0.0586]). The indirect effects of stress through the mediators, as well as the direct effects of stress, were both found to be significant, indicating a partial mediating effect of shoulder pain, shoulder disability, and depression.
| Effect | SE | t | P | 95% BC CI | |
|---|---|---|---|---|---|
| Total effect of stress on health-related quality of life | −0.4408 | 0.0773 | −5.7020 | < 0.001 | [− 0.5926, − 0.2889] |
| Direct effect of stress on health-related quality of life | −0.2598 | 0.0934 | −2.7816 | 0.0056 | [− 0.4433, − 0.0763] |
| Total indirect effect | −0.1809 | 0.0652 | [− 0.3140, − 0.0586] | ||
| Indirect effect via shoulder pain | 0.0679 | 0.0281 | [0.0199, 0.1304] | ||
| Indirect effect via shoulder disability | −0.0414 | 0.0208 | [− 0.0873, − 0.0061] | ||
| Indirect effect via depression | −0.1197 | 0.0573 | [− 0.2401, − 0.0104] | ||
| Indirect effect via shoulder pain and shoulder disability | −0.0733 | 0.0218 | [− 0.1207, − 0.0360] | ||
| Indirect effect via shoulder pain and depression | −0.0065 | 0.0044 | [− 0.0169, − 0.0001] | ||
| Indirect effect via shoulder disability and depression | −0.0029 | 0.0023 | [− 0.0085, 0.0000] | ||
| Indirect effect via shoulder pain, shoulder disability, and depression | −0.0050 | 0.0033 | [− 0.0132, − 0.0003] | ||
| Note. BC CI, bias-corrected confidence interval. | |||||
This study evaluated the extent to which the underlying mechanisms of shoulder pain, shoulder disability, and depression mediate the relationship between stress and health-related quality of life in middle-aged women. Consistent with our conceptual framework, it was determined that: (1) stress negatively correlated with health-related quality of life, (2) shoulder pain, shoulder disability, and depression mediated the relationship between stress and health-related quality of life, and (3) these mediators had indirect effects of stress on health-related quality of life in a sequential manner.
Similar to previous studies, our data also showed a close relationship between stress and health-related quality of life [36, 37]; stress is a risk factor for poor physical and mental health [38]. Middle-aged Korean women experience more stressful events than men, as they perform different social roles within their families, including those related to pregnancy, giving birth, and childcare, and experience events such as separation, divorce, job loss, and disease or death of family members. They often perform repetitive and unpaid household duties in addition to a fixed duration of working hours; therefore, compared to men, they are more vulnerable to stressors that threaten their social and daily lives [39]. Social support at work and home can positively impact an individual’s physical and mental health and reduce stress [40, 41]. Therefore, systematic family and social support should be provided to improve health-related quality of life and reduce and control stress in middle-aged women.
In this study, stress had direct and indirect effects on health-related quality of life through shoulder pain and disability. Psychosocial factors, such as stress or anxiety, further activate pain perception [42, 43]. Shoulder pain often persists even after recovery [44] and, sometimes becomes a chronic condition (lasting for more than three months). It may occur in isolation or may be accompanied by neck or upper-back pain [45]. Humans can perceive stress and can modify their responses to it. Therefore, to reduce shoulder pain or disability caused by stress, it is important to increase adjustment to stress and the threshold to endure it. As chronic pain and stress can be managed and controlled by proper exercise [46], it is necessary to conduct an intervention study in the future to control stress and pain by integrating exercise into the lives of middle-aged women.
This study showed that stress has direct and indirect effects on health-related quality of life mediated by shoulder pain, disability, and depression. These results are consistent with those of previous studies [43, 47], indicating that the higher the depression, the lower the health-related quality of life, and the higher the pain, the higher the depression and the lower the health-related quality of life [48]. The results of this study suggest that stress directly affects health-related quality of life and causes shoulder pain, shoulder disability, and depression, all of which have direct and indirect effects on health-related quality of life. Therefore, controlling and managing stress is important for improving health-related quality of life. Stress has a secondary effect on physical symptoms, such as pain and disability, and mental symptoms, such as depression, as well as a negative effect on the quality of life.
Therefore, healthcare workers, such as nurses, need to implement nursing interventions that prevent and control stress caused by various complex factors experienced by middle-aged women. A previous study [46] reported that stress can be controlled through exercise and physical activity. Exercise has been reported to improve shoulder pain, shoulder disability, depression, and health-related quality of life [49, 50]. Therefore, future studies should develop an intervention program that includes various degrees and types of physical activity to reduce the stress experienced by women in their daily lives, restore their physical health if they have symptoms of physical health conditions and disabilities, and manage mental health conditions such as depression, thereby helping and supporting them in a healthy and happy life.
This study has several limitations. First, only participants living in Seoul, South Korea were included using convenience sampling. Therefore, the study results cannot necessarily be extrapolated to middle-aged women in other countries. Second, this study analyzed the relationship between stress, health-related quality of life, shoulder pain, shoulder disability, and depression based on a self-report survey. Therefore, the cause-and-effect interpretations of these variables cannot be established. Future studies should analyze and interpret data using tools to perform a more detailed and objective evaluation of various factors that affect health-related quality of life in middle-aged women. Despite these limitations, this study provides new insight into the relationship between stress and health-related quality of life and analyzes the degree of direct and indirect effects of shoulder pain, shoulder disability, and depression on stress. Furthermore, this study suggests that improving the health-related quality of life of middle-aged women and reducing stress necessitate the development of interventions to reduce and manage shoulder pain and disability and reduce the depression caused by these physical symptoms.
This study analyzed the relationship between stress and health-related quality of life using serial mediation analysis. Therefore, the direct effect of stress on health-related quality of life was statistically significant. Additionally, according to the serial mediation analysis, the indirect effect of stress on health-related quality of life through shoulder pain, shoulder disability, and depression was found to be statistically significant, and the explanatory power of these variables affecting health-related quality of life was marked at 33%. Thus, the study results highlight the importance of stress in maintaining health-related quality of life and suggest the need to develop specific health promotion programs (e.g., exercise programs) to reduce and control stress. These results further suggest that healthcare workers should develop and implement exercise intervention programs to reduce stress, shoulder pain, shoulder disability, and depression among middle-aged women. It is certain that consistent efforts, including these exercise intervention programs and their evaluations, will enable middle-aged women to lead healthy lives and improve their health-related quality of life.
Ethical Approval and Consent to participate: The research was performed in accordance with the Declaration of Helsinki and must have been approved This study was conducted in accordance with the principles of the Declaration of Helsinki and the study plan and process were approved by the Clinical Ethics Committee of Daejeon University (1040647-202104-HR-023-02). Written consent was obtained from all participants.
Consent for publication: Not applicable
Availability of supporting data: The datasets generated and/or analysed during the current study are not publicly available due but are available from the corresponding author on reasonable request.
Competing Interests: The authors declare that they have no competing interests.
Funding: This research was funded by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (Grant number 2020R1C1C1015358).
Authors’ Contributions: Conceptualization, JO; methodology, ML; software, ML; validation, JO; formal analysis, JO; investigation, JO; resources, ML; data curation, ML and JO; writing—original draft preparation, ML and JO; writing—review and editing, ML and JO; visualization, ML and JO; supervision, ML; project administration, JO. All authors read and approved the final manuscript.
Acknowledgements: We thank all those who have helped in carrying out the research and anonymous reviewers.