Association between presenteeism and mental health among logistic center workers
Article information
Abstract
Background
Workers in logistics centers are always pressed for time to collect and pack products. They also participate in high-intensity manual labor in which various musculoskeletal hazards exist. In the case of logistic center labor, it is estimated that there is a high risk of presenteeism due to the above characteristics which can cause deterioration of workers’ mental health. However, there is insufficient research on this topic.
Methods
Workers in a logistic center were surveyed using an Internet questionnaire. The survey items included demographic characteristics, labor intensity and work-related factors, and mental health aspects such as depression and anxiety. The survey was conducted for about a month from July 26, 2021 and a total of 353 people were analyzed. Through the χ2 test and t-test, the characteristics of workers who experienced presenteeism were examined and the prevalence ratios (PRs) of depression and anxiety experiences were calculated by multivariable Poisson regression. Afterwards, stratification analysis considering gender, the type of contract, and labor intensity was implemented.
Results
In the group that experienced presenteeism, the number of working days per week was higher and fixed-term workers, high labor intensity, and sleep deprivation were more common. In the multi-Poisson regression analysis conducted by adjusting the demographic characteristics, working hours, and work-related factors, the PRs of depression and anxiety were 1.98 (95% confidence interval: 1.24–3.18) and 1.81 (1.22–2.68), respectively. In particular, the p-value for interactions was significant when stratified with the type of contract.
Conclusions
As a result of the study, presenteeism and mental health were associated in logistic center workers. To prevent mental health issues of logistic center workers, management of presenteeism is necessary and a prospective study is needed.
BACKGROUND
Recently, the overall demand for the logistics industry has begun to increase especially after the coronavirus disease 2019 pandemic.1 The logistics industry occupies a large proportion of the world’s economy and can be largely divided into transportation, storage of goods, and packaging materials. The industry controls the overall process of delivering products to consumers at distribution centers and warehouses.2 Labor in logistics center is always pressed for time to collect and pack products ordered. In addition, it is a high-intensity manual labor environment in which various musculoskeletal hazards exist. Due to the nature of the industry, repetitive movements, lifting, moving things, and fast-paced work environments are observed, and it is estimated that there is a high risk of occupational injury.3 Because of the high job demands and low job control, logistic center workers are considered to be at risk of occupational stress and mental health risks are also expected to be high. While there have been studies about mental health in drivers in transport and logistics industries, research on logistic center workers is insufficient.456
Presenteeism has been actively studied in recent years and definitions are being used in various ways. There are 2 largely used definitions of presenteeism.7 One definition is “people, despite complaints and ill health that should prompt rest and absence from work, still turning up at their jobs,” which is referred to as ‘sickness presenteeism’ and is mainly used in the European literature.8910 The second one is a decrease in the productivity of employees while they are on the job, which is also known as ‘health-related productivity loss’ mainly used in the American literature.1112 Presenteeism is a risk factor for future sickness absences and decreased self-rated health.13 There have been various studies which have shown that mental health conditions such as depression and anxiety precede presenteeism. Those studies mainly focused on the second definition dealing with productivity loss, not the first definition of showing up at their jobs while ill.14151617
However, from the perspective of going to work while sick, a few studies have reported that the presenteeism itself would be a risk factor for mental illness.18192021 In terms of workers, attending work while ill is a more important issue than the reduced productivity and if presenteeism acts as a risk factor in mental health, it is very important to evaluate the prevalence of presenteeism and set the policy to decrease presenteeism. But most of the studies have measured indicators including burnout or self-rated health rather than mental symptoms such as depression or anxiety.181920Also, most studies have been conducted on general workers, so research on high-risk groups like logistic center workers is needed.192021
Most workers in logistic centers have high labor intensity, high time pressure during work, and low work autonomy.322 High job demand and low control over the pace of work are associated with presenteeism,182324 which means that workers in logistic centers are at a high risk of presenteeism. Therefore, it is important to understand how presenteeism actually occurs in logistic center workers, what their mental health status is, and to investigate the association between presenteeism and mental health. In this study, we conducted a cross-sectional study to investigate the association between presenteeism and mental health of workers of one logistic center in Korea.
METHODS
Participants
The total number of workers at the logistic center was estimated to be about 20,000. We planned to investigate 1,000 people or 5%. Our study recruited workers in a logistic center together with the labor union of the logistic center for 4 weeks starting from July 26, 2021. The participation URL of the internet survey was distributed through the company bulletin board and social networking services. Using a self-questionnaire, the participants’ demographic data, employment status, job contents, working hours, labor intensity, and health problems were obtained. The total number of responses was 367 and after excluding duplicates and incomplete data, a total of 353 workers were included in the study.
Definition of presenteeism
The definition of presenteeism was given by the Korean Working Conditions Survey (KWCS). The KWCS is a cross-sectional, nationally representative survey conducted periodically by the Korea Occupational Safety and Health Research Institute. In KWCS, presenteeism was evaluated by the following question. “Have you been out and working even though you are sick in the past 12 months?” This current study used the same question to measure presenteeism of the logistic center workers. When participants answered “yes,” it is considered that the participants have presenteeism.
Assessment of mental health
For measuring the depression level of the participants, Patient Health Questionnaire-2 (PHQ-2) was used. PHQ-2 was developed for screening depression.25 The Korean version of PHQ-2 was previously assessed and showed high reliability and validity.26 In PHQ-2, depression is scaled by asking how often you suffered from depressed mood and anhedonia in the last 2 weeks. Answers of “never,” “few days,” “over one week,” and “always” are scored 0, 1, 2, and 3, respectively. When the sum of the scores is over 3, the participants are deemed to be at risk of depression.
In order to measure the anxiety level, the following question referenced by KWCS was used. “Have you had health problems (anxiety) in the past 12 months?” Among those who responded with anxiety symptoms, those who answered that they were related to work were defined as the group with anxiety symptoms.
Other variables
Data regarding the demographic characteristics such as gender and age, health behaviors including smoking and drinking alcohol, and work-related factors were obtained by using a questionnaire. Age was divided into 4 groups: 20–29 years, 30–39 years, 40–49 years, and more than 50 years. Drinking status was classified into normal and heavy drinking, which was defined as drinking more than twice a week and drinking at an average of 7 or more units of alcohol for men and 5 or more units of alcohol for women. Smoking status was classified among never-smoker/ex-smoker and current smoker.
Employment status was categorized as follows based on the participants’ position at the workplace: daily worker and fixed-term worker. In the current study, a daily worker was defined as someone who signed contracts with logistic centers every working day. Fixed-term worker refers to those who were contracted with the company for a fixed period of time such as 3, 9, and 12 months. There were no regular workers in the participants. There are 3 shift schedules for the participants: daytime (8:00–17:00), afternoon (17:00–02:00), and night (21:00–06:00). Those who are scheduled to work in the daytime were classified as day workers, while all others were classified as shift workers. The numbers of daily working hours and weekly working days were part of the questionnaire. Weekly working hours were calculated by daily working hours and weekly working days and classified as “< 35 hours,” “35–52 hours,” and “> 52 hours.”
Labor intensity was measured by the Borg Rating of Perceived Exertion (RPE). RPE is a way of measuring physical activity intensity level.27 Labor intensity is rated from 6 corresponding to “no exertion at all” to 20 representing “maximal exertion” of effort. Examples of the scores were presented in the survey as follows: “6–7: very light like lying down and resting, 9–10: light like daily activities such as folding clothes, 11–12: intermediate like walking normally, 13–14: somewhat difficult walking fast, 15–16: very hard like 100 m running, and over 17: very, very hard like marathon.” If the RPE was 15 points or higher, the workers’ labor intensity was high. The average hours of sleep was considered in the following question. “How many hours do you sleep on average (on working days at the logistic center)?” If the hours of sleep was less than 7 hours, it was defined as sleep deprivation.28
Statistical analysis
The general characteristics of the study participants were evaluated. Continuous variables were expressed as means and standard deviations (SDs), while categorical variables were expressed as frequencies and percentages (%). A χ2 test and t-test were performed to examine the ratio and the differences of demographic and occupational factors according to presenteeism. Age, gender, type of contract, shift work, weekly working hours, and labor intensity were considered potential confounders. When the outcome is common, usually with a prevalence greater than 10%, the prevalence ratio (PR) can be overestimated by the odds ratio (OR) if the PR is greater than 1 or underestimated if the PR is less than 1.29303132 Since the incidence of depression and anxiety is usually high, multiple Poisson regression was performed to evaluate the relationship between presenteeism and mental health (depression and anxiety). To reduce the confounding bias, model I was adjusted for age and gender, while model II was further adjusted for weekly working days, type of contract, shift work, and labor intensity. The analysis determined the PR and 95% confidence interval (CI). In addition, a stratification analysis by gender, type of contract, and labor intensity was conducted to examine modifying factors in the PR between presenteeism and mental health.
If the prevalence of the outcome is not significantly high, there is a literature that the estimated value of the ORs using logistic regression shows a less biased value than PRs.33 Sensitivity analyses were also performed by multivariable logistic regression to evaluate the relationship between presenteeism and mental health. All statistical analyses were performed using SAS (version 9.4; SAS Institute, Cary, NC, USA). Statistical significance was defined as a p-value of < 0.05.
Ethics statement
The present study protocol was approved from review by the Institutional Review Board of The Catholic University College of Medicine (approval No. KC21QISI0562). Informed consent was obtained from all participants of the study.
RESULTS
The general and occupational characteristics of the participants are listed in Table 1. There were slightly more women workers (54.4%) than men (45.6%). The average working period of the participants was 17.2 months (SD 16.3), the average 21.1 months (SD 17.2) for fixed-term workers, and the average 14.3 months (SD 15.1) for daily workers. Presenteeism was present in 174 (49.3%) of the total 353 participants. The average Borg RPE level was 13.66 and workers in high labor intensity (RPE ≥ 15) represented 28.3% of the total. The proportions of depressed and anxious workers were 25.8% and 37.8%, respectively. Fixed-term workers had more presenteeism than daily workers (p < 0.05). In the presenteeism group, they worked more days and harder than the non-presenteeism group (p < 0.05). Also, differences of the hours of sleep were observed depending on presenteeism (p < 0.05).
Table 2 indicates the association between presenteeism and mental health evaluated by multiple Poisson regression. For depression, the PR of presenteeism was 2.31 (95% CI: 1.48–3.61) compared with those of the non-presenteeism group. After adjusting for age and gender, the PR of presenteeism was similarly high at 2.34 (1.49–3.66). Significant results were obtained with a PR of 1.98 (1.24–3.18), even after further adjusting for weekly working hours, type of contract, shift work, and labor intensity. Likewise, the crude PRs, model I, and model II between presenteeism and anxiety were evaluated and were statistically significant with values of 2.07 (1.43–3.00), 2.08 (1.43–3.02), and 1.81 (1.22–2.68), respectively.
Table 3 shows the association between presenteeism and mental health stratified by gender, type of contract, and labor intensity. The p-values for the interactions between gender and presenteeism were not significant. Association between presenteeism and mental health was significant for daily workers. There were significant interactions between presenteeism and the type of contract on depression (p = 0.044), but not on anxiety (p = 0.148). On the other hand, the interactions between labor intensity and presenteeism were not significant.
DISCUSSION
This study aimed to examine the association between presenteeism and mental health in logistic center workers. The results of the current study showed that workers who experienced presenteeism had elevated PRs of depression and anxiety even after adjusting for age, gender, weekly working hours, the type of contract, shift work, and labor intensity (Table 2). In particular, the type of contract had a mediating effect between presenteeism and depression (Table 3).
In Table 1, among the 353 workers, 49.3% of the responders attended work while ill in the past 12 months. In the fifth and sixth KWCS (2017, 2020), presenteeism was present at levels of 17.2% and 12%, respectively. In the sixth European Working Conditions Survey (2015), presenteeism was observed in 39% of responders.34 This means that the participants have more presenteeism than ordinary workers and the value is similar to the nurse job group (50.1%), which is known to be at high risk for presenteeism.35 This means that the workers of this study have more presenteeism than general workers, which implies that they are vulnerable group for presenteeism.
In addition, daily workers and shift workers accounted for more than half. As the amount of logistics increases, the working population in the logistic industry increase which induces the raise of the number of precarious workers. Furthermore, overall sleep and mental health conditions in these workers were poor. The most of participants had sleeping time less than 7 hours. Who are at risk of depression in current study was 25.8% which is more than the prevalence of depression (5.3%) in Korea.36 Who suffered from anxiety symptoms in the participants were 37.8% which is much more than 5% in the sixth KWCS (2020). It is estimated that workers in the logistic centers are at high risk of mental health. There were significant differences in sleeping time, depression, and anxiety between presenteeism and non-presenteeism group (Table 1). Health risk would increase due to the employment instability and labor intensity, which could induce presenteeism.3373839
Our finding regarding associations between presenteeism and mental health are consistent with previous research (Table 2). In the sensitivity analysis, the association between presenteeism and depression and anxiety was also significant when calculated by multivariable logistic regression (Supplementary Table 1).Conway et al.21 reported an effect between sickness presenteeism and depression in a Danish prospective cohort study. Gustafsson and Marklund19 and Taloyan et al.20 studied the relationship between sickness presenteeism and low self-rated health or mental well-being in a Swedish cohort study. From all of the above studies, presenteeism appears to have a negative impact on mental health.
There were several possible mechanisms between presenteeism and mental health. First, presenteeism requires additional effort due to poor performance at work and affected workers have to exert more effort. Excessive effort will hinder the opportunity of recovery and also affect the ability to recovery after work, causing mental disorders such as depression and anxiety.404142 Insufficient recovery accumulates stress and prolonged stress leads to wear and tear on the body (allostatic load). Allostatic load induces the release of stress hormones, adrenalin and cortisol, and if repeated, should lead to atrophy of neurons and changes of brain structure and function, which cause major depressive illness and anxiety disorder.42
A second possible mechanism is that presenteeism itself could increase the level of occupational stress which worsens mental health.43 The most important model that explains occupational stress is the demand-control model.44 In the job demand-control model, presenteeism means workers do not have enough control not to attend the workplace even if they are sick. When they are going to work while ill, they have to exert more effort to perform the same job as before, although they have already performed a lot of labor-intensive logistic center work. High job strain and low job control can induce deterioration of mental health.4546
A third possible explanation is if workers who are sick attend work, the workers’ low productivity may worsen their relationship with colleagues and supervisors. These social stressors, for example conflicts with co-workers and supervisors in addition to a negative group climate, leads to a decrease of self-esteem and increases of anxiety and depressive symptoms.47
In the subgroup analysis, it was confirmed that daily workers are more vulnerable to mental health effects of presenteeism than fixed-term workers (p for interaction = 0.044) (Table 3). It can be explained that the daily workers have less job control than fixed-term workers, which increase occupational stress. For example, in the case of daily workers, even though they do not want to, the work in the logistic center suddenly change according to the instructions of their superiors. Also, there are experiences of different wages or actual discrimination due to the different type of contract. There are no annual leave in daily workers. When presenteeism is inevitably caused to prevent the loss of income and protect the continuous employment, mental stress is also expected to occur.
The limitations of this study are as follows. First, we did not inquire about the socioeconomic status of the participants such as income and educational status, which can affect presenteeism and mental health.37 Second, recall bias may occur due to the limitations of the survey. Third, due to the lack of a large sample size, it cannot be assumed to be representative of the Korean entire logistic industry. We conducted the survey for a long time to include as many people as possible, but it was not easy to predict how many people would register. Also, it was difficult to access due to the nature of fixed-term and daily workers. However, it was not recruited from a specific biased group, and even if the number of respondents cannot represent the entire logistic industry, it is judged that it is not a problem in terms of association rather than prevalence. Forth, causality is not guaranteed because this study is a cross-sectional study. In particular, there have been several studies evaluating the link between mental illness such as depression14 and anxiety16 and presenteeism, so the reverse causality cannot be excluded. However, as explained in the background of this study, presenteeism was measured as an index of loss of work productivity in the case of the above studies, which is different from this study. In order to address these limitations, more prospective studies on presenteeism and mental health with a large sample size are needed.
On the contrary, there are several strengths of this study. This is the first study which researched the association between presenteeism and mental health for logistic center workers. Stratification with gender, the type of contract, and labor intensity were also evaluated to investigate the relationship between presenteeism and mental health. Based on the results of this study, it is suggested that intervention is necessary for logistic center workers who experience presenteeism which can adversely affect mental health.
CONCLUSIONS
Logistic center workers who show presenteeism had significantly elevated PRs of depression and anxiety. The results of this study suggest that presenteeism could worsen the mental health of logistic center workers and the type of contract mediates the relationship between presenteeism and depression. To prevent presenteeism and presenteeism related mental problems, laws and systems such as “paid sick leave” and “sickness-benefit” should be established in Korea. In addition, it is important to lower the labor intensity and resolve job insecurity in logistic centers. More prospective research is needed to discuss how presenteeism affects mental health and what factors mediate the impacts.
ACKNOWLEDGEMENTS
The authors would like to thank the labor union of the logistic center.
Notes
Competing interests: The authors declare that they have no competing interests.
Author contributions:
Conceptualization: Kim HR.
Data curation: Yoo H, Song JH.
Formal analysis: Yoo H, Song JH, Kim HR.
Validation: Kim HR.
Visualization: Yoo H.
Writing - original draft: Yoo H.
Writing - review & editing: Song JH, Kim HR.
Abbreviations
CI
confidence interval
KWCS
Korean Working Conditions Survey
OR
odds ratio
PHQ-2
Patient Health Questionnaire-2
PR
prevalence ratio
RPE
Rating of Perceived Exertion
SD
standard deviation