Introduction
The purpose of this cohort-based study was to investigate the extent to which cortisol levels were associated with sickness absence and the relationships between workplace bullying and sickness absence through the prism of cortisol use (Grynderup et al., 2017). Inclusion criteria were based on the necessity to participate in two Danish cohorts, known as the Psychological Risk Factors for Stress and Mental Disease (PRISME) and the Workplace Bullying and Harassment (WBH), and the identification of cortisol levels due to long-term sickness absence (LTSA) or workplace bullying. Exclusion criteria included all observations where information about one of the variables was missing. To be more exact, the observations with LTSA during the last two years and the participants who did not gather their cortisol samples were excluded from the study.
Main body
Five hundred, four thousand eighteen participants contributed to the study with their 7451 observations meeting the inclusion criteria. This number was the result of the three-round data collection. At the first stage, 10,036 participants of the PRISME study, including hospital employees and servants were invited to take a questionnaire and gather saliva samples. At the second stage, 3224 participants from the WBH study joined the investigation and took the same steps. Participants were randomized for the third round regarding their questionnaire responses and ability to obtain their saliva samples. Participants shared their saliva samples three times with about two years in between, meaning that the length of the current study was approximately six years. No treatment information was given because of its initial goal, the investigation of the association between workplace bullying and LTSA (Grynderup et al., 2017). Statistics, causation, and sensitivity analyses were developed to investigate the peculiarities of bullying and sickness absence among people with different occupations and stress levels.
Several types of measurements were used in this study. First, it was necessary to measure workplace bullying using one question with strict replies such as “never”, “now and then”, “monthly”, “weekly”, or “daily”. Second, the measurement of cortisol levels was required, using such methods as the spectra cortisol coated tube Radioimmunoassay and the liquid chromatography-tandem mass spectrometry method. Salvia was assessed at three time points, at the end of each of three rounds of the study.
High cortisol level was associated with sickness absence risk decreased at evening time (odds ratio was 0.82 and confidence interval was 0.68-0.99). Morning cortisol levels did not indicate significant changes (OR – 0.98, and CI – 0.81-1.18) (Grynderup et al., 2017). In general, there were no evident reasons to believe that cortisol could mediate the relationships between LTSA and workplace bullying.
Conclusion
The strengths of this study included its larger sample compared to previous investigations in this field, thorough adjustments used to identify awakening and sampling time, and follow-up period with the help of which it was possible to observe participants’ conditions during a certain period. The results of the study were based on self-reported measures of workplace bullying. However, the same feature could be identified as a weakness of the study due to its biased nature of understanding illnesses or bullying. Another weakness of this article was a simple measurement method used to check the cortisol level at different periods. These limitations can be improved in future research in case the conditions under which cortisol samples should be gathered are changed, and new measurements are chosen.
Reference
Grynderup, M.B., Nabe-Nielsen, K., Lange, T., Conway, P.M., Bonde, J.P., Garde, A.H., … Hansen, A.M. (2017). The associations between workplace bullying, salivary cortisol, and long-term sickness absence: A longitudinal study. BMC Public Health, 17(1), 710-720.