Abstract
The current study sought to clarify the relationship between the self-administered Brief Job Stress Questionnaire (BJSQ) and urinary biopyrrin levels, which are elevated in response to stress. A cross-sectional study was conducted with employees of companies in Kanagawa, Japan. Participants were asked to complete the BJSQ and ad hoc questionnaires, and urinary biopyrrin levels were measured. We investigated the correlations between psychological and physical stress response scores on the BJSQ and urinary biopyrrin levels. Correlations between subscale scores of the BJSQ and urinary biopyrrin levels were then examined. Additionally, differences in urinary biopyrrin levels were examined using ad hoc questionnaires. In total, 105 subjects participated in this study. No correlations were found between stress response scores and urinary biopyrrin levels. For the 2 subscales of the BJSQ (suitable jobs and meaningfulness of work), the higher the score, the higher the urinary biopyrrin levels. Analysis of ad hoc questionnaire results revealed that urinary biopyrrin levels were significantly higher in individuals who requested regular stress checks by urine testing, compared with those that did not. The results suggested that urinary biopyrrin levels may be an indicator of individuals’ overadjustment to the work environment. A follow-up study will be necessary to investigate the development of psychiatric disorders in individuals with high urinary biopyrrin levels.
Keywords: biopyrrin, Brief Job Stress Questionnaire, ME-BYO, stress, workers, work-related stress
1. Introduction
In Japan, business entities that manage 50 or more employees are currently mandated to conduct a stress check at least once a year to screen employees with high psychosocial stress in the workplace. This requirement is in accordance with the “Ministry of Health, Labour and Welfare (MHLW) edition stress check implementation program” launched in December 2015, as prescribed in article 66-10 of the Industrial Safety and Health Act. The Ministry of Health, Labour and Welfare recommends the use of the Brief Job Stress Questionnaire (BJSQ) which is a self-administered instrument that has been validated as a stress assessment scale for workers in Japan.[1]
The BJSQ was developed by Shimomitsu et al on the basis of the Occupational Stress Model of the United States National Institute for Occupational Safety and Health.[1] The BJSQ is a subjective self-evaluation instrument with verified statistical reliability and validity.[1] Subjective evaluation scales can benefit from the implementation of objective indicators. Therefore, it may be useful to establish a simple and objective stress rating scale in addition to the BJSQ.
Previous studies have reported associations between the BJSQ and salivary and nail cortisol, blood cytokines, and heart rate variability.[2–5] However, these associations have not been confirmed in subsequent studies. Stress is primarily classified into physical stress and psychological stress. Additionally, oxidative stress is a type of stress that occurs within the body in relation to physical and psychological stress. To date, the relationship between the BJSQ and oxidative stress markers has not been investigated.
It has been reported that physical and psychological stress causes the production of excessive reactive oxygen species in vivo.[6–8] Bilirubin has strong antioxidant properties in vitro and functions as a scavenger against reactive oxygen species generated in vivo.[9–11] The end product of bilirubin metabolism is biopyrrin, which is excreted in the urine.[12] A previous study reported that chronic social stress increased urinary biopyrrin levels in mice.[13] In addition, Yamaguchi et al reported that urinary biopyrrin levels increase significantly with acute psychological stress in humans.[14] Therefore, urinary biopyrrin levels are considered to be a biomarker reflecting psychological stress.
Investigating the relationship between urinary biopyrrin levels, a biomarker of psychological stress, and subjective stress rating scales may produce valuable findings. In a study examining this topic in Egypt, Mourad et al reported that scores on the Occupational Stress Index (OSI), a self-administered stress rating scale, were correlated with urinary biopyrrin levels in brickfield workers.[15] On the basis of this result, we hypothesized that a positive correlation exists between BJSQ scores and urinary biopyrrin levels. Therefore, we conducted the present study to investigate the relationships between the BJSQ, stress-related factors, and urinary biopyrrin levels among workers at companies in Japan.
2. Methods
2.1. Study design and participants
The present study was conducted from October 2022 to March 2023. The study was accepted for the Kanagawa ME-BYO Living Lab program in November 2022. The program is one of the Healthcare New Frontier policy programs operated by Kanagawa Prefecture on the basis of the ME-BYO concept.[16] The ME-BYO concept originated in ancient China, and in modern usage refers to the state of all physical and mental conditions between health and the onset of disease.[16]
The inclusion criteria were as follows: aged 20 to 59 years and currently employed. The exclusion criteria were as follows: currently undergoing treatment for a disease, currently menstruating, or currently pregnant. Participants were recruited through the Kanagawa ME-BYO Living Lab. The estimated sample size was 200 participants with an estimated dropout rate of 10% during the study period. Under the supervision of the Kanagawa ME-BYO Living Lab committee, companies and institutions in Kanagawa Prefecture with 50 or more employees were invited to apply, and 105 people from 8 companies expressed interest in participation. After obtaining consent to participate in the study via a website, participants were asked to complete questionnaires regarding demographic information, lifestyle, stressors, methods of stress reduction, and requests for regular stress checks. Participants were given the BJSQ response forms and commercially available Postal urine container kit for measuring biopyrrins (Anatech Inc., Tokyo, Japan) and asked to mail them back. Urine samples sent by mail were stored in a freezer at − 80°C and thawed immediately before measurement. The questionnaire was administered on the website using a Macromill questionnaire form (Macromill Inc., Tokyo, Japan). The primary endpoint was the correlation between psychological and physical stress response scores on the BJSQ and urinary biopyrrin levels. Secondary endpoints were correlations between subscale scores of the BJSQ and urinary biopyrrin levels, and differences in urinary biopyrrin levels for each questionnaire item. This study was approved by the Medical Research Ethics Committee, Shimane University Faculty of Medicine (approval number: KS20220726-1).
2.2. Questionnaire on demographics and perceived stress
Age, gender, height, weight, body mass index, years of education, residential status, job type (management, sales, manufacturing/production, service, technology development, information systems, and others), position (management/executives, department managers, section chiefs, assistant chiefs, general employees, specialized positions, and others), working hours per week (40 hours or fewer), hours of sleep per day, perceived stress level in the past month, perceived stress level in this morning, stressors (money, health, work relationships, relationships with family and friends, anxiety about the future, work, other, and absence of stress), and methods of stress reduction (exercise, sleep, yoga/meditation, pets, TV/movies/videos, smoking, eating, talking with others, playing games, drinking, reading, shopping, social networking services, music, other, and absence of stress reduction methods).
2.3. Ad hoc questionnaire
We developed 3 questions, as follows. When your stress levels are high, do you request a consultation with an industrial physician, a counselor, or other specialist? (yes/no). If your stress levels are high, do you request a consultation with your company or supervisor about improving your working environment? (yes/no). Do you request regular stress checks via urine testing? (yes/no).
2.4. Brief Job Stress Questionnaire
The BJSQ is a self-administered instrument consisting of 57 items, each of which is rated on a Likert scale from 1 to 4.[1] The BJSQ consists of 4 parts: Part A: job stressors (17 items), Part B: psychological and physical stress responses (29 items), Part C: social support (9 items), and Part D: job and life satisfaction (2 items). Part A has 9 subscales: quantitative job overload, qualitative job overload, physical demands, interpersonal conflict, poor physical environment, job control, skill utilization, suitable jobs, and meaningfulness of work. Part B has 6 subscales: vigor, anger-irritability, fatigue, anxiety, depression, and physical stress response. Part C has 3 subscales: supervisor support, coworker support, and support from family and friends. The reliability of each scale has previously been verified using Cronbach alpha reliability coefficient, and factorial validity has been confirmed by the main factor method plus varimax rotation.[1] Cronbach alpha coefficients were 0.74, 0.84, 0.81, and 0.83 for job stressors, psychological stress response, physical stress response, and social support, respectively.[1] Higher scores in each of the 4 parts indicate a higher degree of stress. Higher scores in the following subscales indicate a higher level of stress: quantitative job overload, qualitative job overload, physical demands, interpersonal conflict, poor physical environment, anger-irritability, fatigue, anxiety, depression, and physical stress response. Lower scores in the following subscales indicate a higher level of stress: job control, skill utilization, suitable jobs, meaningfulness of work, vigor, supervisor support, coworker support, and support from family and friends.
2.5. Measurement of urinary biopyrrin and creatinine
Urinary biopyrrin concentration was measured using a Redox assay biopyrrin enzyme-linked immunosorbent assay kit (Metallogenics Co., Ltd., Chiba, Japan). This kit has been used in several studies.[15,17–19] Urinary creatinine concentration was measured by LabAssayTM Creatinine (FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan). Biopyrrin values used in the analysis were corrected for subjects’ physiological factors, such as renal function, food and water intake, sweat volume, and urine volume by dividing by creatinine values.
2.6. Statistical analysis
We calculated the sample size for exploratory analysis. The sample size was set to 200 cases with a power of 0.8, a significance level of 0.05, a correlation coefficient of 0.2, and an expected dropout rate of 10% using statistical software R 3.4.3 (R Foundation, Vienna, Austria). SPSS version 27 (IBM Corp., Armonk) was used for statistical analysis. Correlations between urinary biopyrrin levels and age, body mass index, psychological and physical stress response scores of the BJSQ, and subscale scores of the BJSQ were analyzed using Spearman correlation coefficient. Multiple regression analysis was performed using factors that exhibited a significant correlation. The Mann–Whitney U test was used to compare the 2 groups (binary variables of background information, presence of stress-related factors, and yes or no responses in ad hoc questionnaire) using urinary biopyrrin levels. P values < .05 were considered statistically significant.
3. Results
A total of 105 individuals from 8 companies agreed to participate in this study and completed the web-based questionnaire. Of these, 5 participants did not return BJSQ response forms or urine samples. Additionally, 4 participants’ BJSQ responses were deemed invalid because of omissions or duplicated answers. Therefore, the final statistical analysis was conducted on 96 participants’ data.
Table 1 shows participants’ demographic information, scores for the 4 parts of the BJSQ, and correlations with and differences in urinary biopyrrin levels. No significant correlations with urinary biopyrrin levels were found for age, body mass index, and BJSQ scores in the 4 parts. In addition, there were no significant differences in urinary biopyrrin levels regarding gender, years of education, residential status, job type, position, working hours per week, or hours of sleep per day.
Table 1.
Participants’ demographic information, scores for 4 parts of the BJSQ, and correlations with and differences in urinary biopyrrin levels.
| Characteristics or measures | Number or mean ± SD | Correlation with (r) and differences in urinary biopyrrin levels (mean ± SD) |
|---|---|---|
| Age (yrs) | 43.3 ± 9.2 | r = −0.046, P = .653 |
| Gender (male/female) | 56/40 | 1.03 ± 0.56/1.17 ± 0.48, P = .088 |
| Body mass index (kg/m2) | 22.3 ± 3.9 | r = −0.161, P = .118 |
| Years of education (<16/16≤) | 21/74 | 0.99 ± 0.43/1.12 ± 0.56, P = .422 |
| Living (alone/other) | 16/80 | 1.26 ± 0.48/1.06 ± 0.54, P = .129 |
| Job type (management/other) | 55/41 | 1.05 ± 0.45/1.15 ± 0.63, P = .571 |
| Position (section chief and above/other) | 37/59 | 1.19 ± 0.64/1.03 ± 0.45, P = .447 |
| Working hours per week (≤40/40<) | 50/46 | 1.15 ± 0.62/1.02 ± 0.42, P = .441 |
| Hours of sleep per day (<6/6≤) | 34/62 | 1.06 ± 0.55/1.11 ± 0.52, P = .553 |
| Scores of the BJSQ (points) | ||
| A: Job stressors | 38.6 ± 5.7 | r = −0.164, P = .109 |
| B: Psychological and physical stress responses | 58.5 ± 14.0 | r = −0.103, P = .317 |
| C: Social support | 19.3 ± 5.7 | r = −0.040, P = .701 |
| D: Job and life satisfaction | 4.1 ± 1.5 | r = −0.146, P = .155 |
| Urinary biopyrrin levels (µmol/g creatinine) | 1.09 ± 0.53 |
BJSQ = Brief Job Stress Questionnaire, SD = standard deviation.
Next, we examined the correlations between subscale scores of the BJSQ and urinary biopyrrin levels. The results revealed significant correlations with urinary biopyrrin levels for job control (r = 0.242, P = .018), suitable jobs (r = 0.249, P = .014), meaningfulness of work (r = 0.235, P = .021), and anger-irritability (r = −0.202, P = .049; Table 2). Significant correlations were also found between job control and suitable jobs (r = 0.344, P = .001), meaningfulness of work (r = 0.440, P < .001), and anger-irritability (r = −0.348, P = .001; Table 2). Additionally, we found significant correlations between suitable jobs and meaningfulness of work (r = 0.668, P < .001), and between meaningfulness of work and anger-irritability (r = −0.256, P = .012; Table 2). A multiple regression analysis showed significant correlations in suitable jobs (β = 0.261, P = .010) and meaningfulness of work (β = 0.296, P = .004; Table 3).
Table 2.
Spearman correlation between subscale scores of the BJSQ and urinary biopyrrin levels (n = 96).
| Variable | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. Age | .262* | −0.046 | −0.130 | −0.044 | 0.072 | 0.120 | −0.198 | −0.157 | −0.086 | 0.009 | −−0.067 | −0.110 | 0.082 | −0.144 | −0.048 | −0.020 | −0.010 | −0.100 | −0.079 | −0.005 |
| 2. Body mass index | – | −0.161 | −0.049 | −0.060 | 0.019 | 0.025 | −0.066 | 0.042 | 0.015 | 0.039 | 0.082 | 0.154 | −0.083 | −0.148 | −0.035 | 0.002 | −0.124 | 0.036 | −0.004 | 0.041 |
| 3. Urinary biopyrrin levels | – | 0.091 | 0.112 | −0.130 | −0.160 | −0.015 | .242* | 0.185 | .249* | .235* | 0.109 | −.202* | −0.109 | 0.031 | −0.104 | 0.042 | 0.035 | 0.050 | 0.030 | |
| 4. Quantitative job overload | – | .693** | .262** | −0.056 | −0.047 | −0.135 | .215* | .286** | .275** | 0.057 | 0.089 | .214* | .218* | 0.033 | 0.044 | 0.030 | 0.076 | −0.071 | ||
| 5. Qualitative job overload | – | .355** | −0.074 | −0.142 | 0.030 | .221* | .212* | .310** | 0.107 | −0.013 | 0.111 | 0.152 | −0.080 | 0.065 | 0.155 | 0.122 | 0.033 | |||
| 6. Physical demands | – | 0.120 | 0.035 | −0.093 | 0.032 | 0.030 | .209* | 0.115 | 0.107 | 0.116 | −0.061 | −0.035 | 0.134 | 0.045 | 0.016 | −0.061 | ||||
| 7. Interpersonal conflict | – | .327** | −.272** | −.446** | −.353** | −.427** | −.301** | .472** | 0.174 | .322** | .430** | 0.179 | −.399** | −.448** | −.300** | |||||
| 8. Poor physical environment | – | −0.059 | −.225* | −.203* | −.203* | −0.200 | 0.084 | −0.005 | 0.084 | 0.157 | 0.128 | −0.129 | −0.172 | 0.029 | ||||||
| 9. Job control | – | −.484** | .344** | .440** | .487** | −.348** | −.362** | −.281** | −.363** | −.289** | .402** | .436** | .257** | |||||||
| 10. Skill utilization | – | .572** | .700** | .447** | −.231* | −.245* | −.272** | −.376** | −.208* | .429** | .393** | 0.073 | ||||||||
| 11. Suitable jobs | – | .668** | .256* | −0.028 | −0.034 | −0.043 | −0.157 | −0.065 | 0.097 | 0.193 | 0.059 | |||||||||
| 12. Meaningfulness of work | – | .474** | −.256* | −0.189 | −.216* | −.380** | −0.044 | .334** | .393** | 0.130 | ||||||||||
| 13. Vigor | – | −.341** | −.436** | −.502** | −.590** | −.364** | .255* | .340** | .279** | |||||||||||
| 14. Anger-irritability | – | .468** | .482** | .541** | .202* | −.470** | −.338** | −.287** | ||||||||||||
| 15. Fatigue | – | .648** | .647** | .425** | −.363** | −.290** | −.345** | |||||||||||||
| 16. Anxiety | – | .766** | .365** | −.393** | −.340** | −.322** | ||||||||||||||
| 17. Depression | – | .494** | −.482** | −.380** | −.424** | |||||||||||||||
| 18. Physical stress response | – | −.312** | −.293** | −.295** | ||||||||||||||||
| 19. Supervisor support | – | .704** | .268** | |||||||||||||||||
| 20. Coworker support | – | .351** | ||||||||||||||||||
| 21. Support from family and friends | – |
P < .05.
P < .01.
Table 3.
Multiple regression analysis between the subscale scores of the BJSQ and urinary biopyrrin levels.
| Model 1 β† |
Model 2 β† |
Model 3 β† |
|
|---|---|---|---|
| Age | 0.011 | 0.017 | 0.016 |
| Gender | 0.120 | 0.141 | 0.160 |
| Job control | 0.162 | ||
| Suitable jobs | .261* | ||
| Meaningfulness of work | .296** | ||
| Anger-irritability | −0.167 |
Model 1: adjusted for age, gender, and job control.
Model 2: adjusted for age, gender, suitable jobs, and anger-irritability.
Model 3: adjusted for age, gender, and meaningfulness of work.
P < .05.
P < .01.
Standardized regression coefficient.
In addition, we examined differences in urinary biopyrrin levels between different perceived stress levels, stressors, and methods of stress reduction. No significant differences were found (Table 4).
Table 4.
Comparison of urinary biopyrrin levels and perceived stress level, stressors, and methods of stress reduction.
| Number | Biopyrrins (µmol/g creatinine) Mean ± SD |
P-value | |
|---|---|---|---|
| Perceived stress level (few/above moderate) | |||
| In the past month | 63/33 | 1.08 ± 0.51/1.11 ± 0.58 | .835 |
| In this morning | 74/22 | 1.11 ± 0.52/1.02 ± 0.58 | .266 |
| Stressors (yes/no) | |||
| Money | 40/56 | 1.09 ± 0.54/1.09 ± 0.53 | .976 |
| Health | 35/61 | 1.03 ± 0.47/1.13 ± 0.57 | .530 |
| Work relationships | 70/26 | 1.14 ± 0.57/0.97 ± 0.40 | .364 |
| Relationships with family and friends | 22/74 | 1.05 ± 0.48/1.10 ± 0.55 | .800 |
| Anxiety about the future | 32/64 | 1.08 ± 0.47/1.09 ± 0.57 | .786 |
| Work | 30/66 | 0.99 ± 0.42/1.14 ± 0.57 | .378 |
| Other | 4/92 | 0.93 ± 0.36/1.10 ± 0.54 | .691 |
| Absence | 5/91 | 0.71 ± 0.06/1.11 ± 0.54 | .068 |
| Methods of stress reduction (yes/no) | |||
| Exercise | 40/56 | 1.16 ± 0.58/1.04 ± 0.49 | .446 |
| Sleep | 53/43 | 1.12 ± 0.52/1.06 ± 0.55 | .591 |
| Yoga/meditation | 40/56 | 1.14 ± 0.56/1.05 ± 0.51 | .446 |
| Pets | 50/46 | 1.12 ± 0.60/1.06 ± 0.45 | .942 |
| TV/movies/videos | 28/68 | 1.17 ± 0.56/1.06 ± 0.52 | .386 |
| Smoking | 27/69 | 1.07 ± 0.51/1.10 ± 0.54 | .645 |
| Eating | 17/79 | 1.14 ± 0.54/0.86 ± 0.46 | .053 |
| Talking with others | 8/88 | 1.28 ± 0.49/1.07 ± 0.54 | .241 |
| Playing games | 46/50 | 1.10 ± 0.57/1.09 ± 0.50 | .959 |
| Drinking | 42/54 | 1.14 ± 0.57/1.05 ± 0.50 | .375 |
| Reading | 6/90 | 0.84 ± 0.35/1.11 ± 0.54 | .214 |
| Shopping | 21/75 | 1.27 ± 0.67/1.04 ± 0.48 | .223 |
| Social networking services | 9/87 | 0.91 ± 0.41/1.10 ± 0.54 | .232 |
| Music | 13/83 | 1.01 ± 0.45/1.10 ± 0.55 | .438 |
| Other | 8/88 | 1.04 ± 0.24/1.10 ± 0.55 | .863 |
| Absence | 2/94 | 0.82 ± 0.00/1.10 ± 0.54 | .537 |
SD = standard deviation.
Furthermore, we examined differences in urinary biopyrrin levels using ad hoc questionnaires. The results showed that urinary biopyrrin levels were significantly (1.5 times) higher in individuals that requested regular stress checks via urine testing compared with those who did not (Table 5). Next, we compared the scores of the 4 subscales that were significantly correlated with urinary levels of biopyrrin between individuals who did and did not request regular urine testing (job control, suitable jobs, meaningfulness of work, and anger-irritability). The results showed that job control scores were significantly higher (P = .023) and anger-irritability scores were significantly lower (P = .005) in the group that requested testing. No significant differences were found for suitable jobs scores (P = .514) or meaningfulness of work scores (P = .125).
Table 5.
Comparison of the responses to ad hoc questionnaires and urinary biopyrrin levels.
| Number | Biopyrrins (µmol/g creatinine) Mean ± SD |
P-value | |
|---|---|---|---|
| 1. When your stress levels are high, do you request a consultation with an industrial physician, a counselor, or other specialist? (yes/no) | 44/52 | 1.04 ± 0.45/1.13 ± 0.60 | .678 |
| 2. If your stress levels are high, do you request a consultation with your company or supervisor about improving your working environment? (yes/no) | 33/63 | 0.98 ± 0.44/1.15 ± 0.57 | .144 |
| 3. Do you request regular stress checks via urine testing? (yes/no) | 72/24 | 1.19 ± 0.53/0.79 ± 0.43 | <.001 |
SD = standard deviation.
4. Discussion
In the present study, no significant correlation was found between psychological and physical stress response scores of the BJSQ and urinary biopyrrin levels. However, significant correlations were found between urinary biopyrrin levels and subscale scores of the BJSQ (job control, suitable jobs, meaningfulness of work, and anger-irritability). In addition, the group that requested regular stress checks via urine testing also had significantly higher urinary biopyrrin levels than the group that did not. To the best of our knowledge, this is the first study to report a correlation between BJSQ subscale scores and urinary biopyrrin levels.
In the current study, the primary endpoint (psychological and physical stress response scores of the BJSQ) was not correlated with urinary biopyrrin levels. Previously, Mourad et al reported that OSI scores were correlated with urinary biopyrrin levels in brickfield workers, who were identified as having higher stress than general workers using the OSI.[15] One factor that may have contributed to the lack of a significant correlation in our study is that we included a general sample of company employees, whereas Mourad et al included a high-stress group.[15] Although urinary biopyrrin levels are thought to increase with psychological stress,[14] it may have been difficult to identify a significant correlation among workers in a general employee population. Additionally, the use of a different stress rating scale may have influenced our results. In future studies, it may be useful to examine urinary biopyrrin levels in groups identified by the BJSQ as having higher stress than the general workforce.
The current results revealed a significant correlation between urinary biopyrrin levels and anger-irritability. The lower the anger-irritability score, the higher the urinary biopyrrin levels. Interestingly, Kawamura and Kobayashi reported that a lesser degree of irritability on the BJSQ is a predictor of subsequent long-term psychiatric leave among employees.[20] They speculated that this characteristic may reflect the “typus melancholicus” described by Tellenbach.[20] Considering our results, it is possible that consciously or unconsciously suppressing anger-irritability in the workplace is associated with an increase in urinary biopyrrin levels. Further research will be needed to verify the direction of the correlation.
In this study, the multiple regression analysis also revealed significant correlations between urinary biopyrrin levels and suitable jobs, and the meaningfulness of work. This is the first study to report that urinary biopyrrin levels were higher in individuals who felt that they were better suited to their work and more fulfilled in their jobs. As an example of the paradoxical results of BJSQ and biomarkers, Hirokawa et al reported that the higher the job control score, the higher the salivary cortisol level.[5] These findings suggest either that trying to work adaptively causes high urinary biopyrrin levels, or that high urinary biopyrrin levels enable individuals to work adaptively. High urinary biopyrrin levels have been suggested to be associated with depression,[21] and it may be useful to investigate individuals with high urinary biopyrrin levels in longitudinal studies to determine whether they develop depression.
In the current study, urinary biopyrrin levels were significantly (1.5 times) higher in individuals who requested regular stress checks via urine testing compared with those who did not. In addition, the group that requested examination had higher scores for job control and lower scores for anger-irritability. A previous regional survey of health checkup data reported that respondents who self-evaluated their health status as good had a higher rate of checkups than those who self-evaluated their health status as poor.[22] This result is consistent with the current finding that individuals who requested to be tested reported a higher degree of control over their work and being less irritable. This group may have a higher level of awareness of their own health. The current study is the first to report a relationship between urinary biopyrrin levels and examination behavior. Further studies of this issue are warranted.
The current study involved several limitations. First, the study was limited to a small number of subjects. The number of participants in this study was <200, which was fewer than expected, and the detection power was limited. Therefore, detection power is limited. It will be necessary for future studies of this issue to examine a larger sample. Second, because this study was limited to companies in Kanagawa Prefecture, it will be necessary for future research to examine this issue in a wider area. Third, the sample in this study was heterogeneous, combining participants from different companies. In future, it would be desirable to conduct studies using homogenous samples. Fourth, the BJSQ is a self-assessment and may be underestimated or overestimated. Fifth, we were unable to completely rule out factors that could potentially affect urinary biopyrrin levels. Sixth, the current study did not examine high-stress individuals or individuals who were not working. This issue should be addressed in future studies.
5. Conclusion
This is the first study to report that urinary biopyrrin levels are correlated with suitable jobs and meaningfulness of work as assessed by the BJSQ, and that urinary biopyrrin levels were significantly higher among individuals who requested regular objective stress checks. The results suggested that urinary biopyrrin levels may be associated with overadjustment. However, because this was a secondary analysis, the current results should be verified in future studies. Additionally, a follow-up study examining the development of psychiatric disorders in people with high urinary biopyrrin levels may produce helpful findings. Because our study area was limited and the sample size was small, it would be valuable for future research to examine other geographic areas and a larger sample of workers.
Acknowledgments
We would like to thank the Governor of Kanagawa Prefecture, Yuji Kuroiwa, for his support and Mr Kenichi Oki, Associate Director General (Healthcare Innovation), Policy Bureau Kanagawa Prefectural Government, for his excellent mentorship throughout the research. We thank Benjamin Knight, MSc, from Edanz (https://jp.edanz.com/ac), for editing a draft of this manuscript.
Author contributions
Conceptualization: Koji Otsuki, Rui Shuhama, Rei Wake, Masatoshi Inagaki.
Data curation: Koji Otsuki, Rui Shuhama.
Formal analysis: Koji Otsuki.
Funding acquisition: Rui Shuhama.
Investigation: Koji Otsuki.
Supervision: Masatoshi Inagaki.
Writing – original draft: Koji Otsuki.
Writing – review & editing: Koji Otsuki, Rui Shuhama, Rei Wake, Masatoshi Inagaki.
Abbreviations:
- BJSQ
- Brief Job Stress Questionnaire
- OSI
- Occupational Stress Index
This study was funded by Dai-ichi Life Insurance Company, Ltd. and Dai-ichi Life Holdings, Inc.
This study was approved by the Medical Research Ethics Committee, Shimane University Faculty of Medicine (approval number: KS20220726-1).
KO has received honoraria for lectures from Otsuka, Meiji, Sumitomo Pharma, Viatris, Takeda, and Yoshitomiyakuhin. MI has received grants from Astellas, Eisai, Otsuka, Shionogi, Daiichi Sankyo, Sumitomo Pharma, Takeda, Mitsubishi Tanabe Pharma, Nihon Medi-Physics, Pfizer, Fujifilm, and Mochida; and has received honoraria for lectures from EA Pharma, Meiji, MSD, Viatris, Eisai, Otsuka, Sumitomo Pharma, Takeda, Eli Lilly, Nippon Shinyaku, Pfizer, Mochida, Janssen and Yoshitomiyakuhin. The remaining authors have no conflicts of interest to disclose.
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
How to cite this article: Otsuki K, Shuhama R, Wake R, Inagaki M. Relationship between psychological and physical work-related stress and urinary biopyrrin levels: A cross-sectional study. Medicine 2025;104:37(e44547).
We declare that AI was not utilized in any stages of the hypothesis, data collection, data evaluation, manuscript preparation.
Contributor Information
Rui Shuhama, Email: shuhama@dlri.co.jp.
Rei Wake, Email: rei@med.shimane-u.ac.jp.
Masatoshi Inagaki, Email: minagaki@med.shimane-u.ac.jp.
References
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