Exposure to organisational injustice and serious psychological distress: longitudinal analysis of details of exposure from a private Japanese company

OBJECTIVES: Studies have shown that organisational injustice (OIJ) is associated with mental disorders. However, there is little research regarding details on OIJ exposure. We examined the effect of OIJ on serious psychological distress (SPD) by considering the exposure frequency, the exposure duration and the OIJ-free period after the disappearance of exposure. METHODS: We used a prospective cohort design. OIJ exposure was assessed three times with 1-year intervals between assessments, and the subjects were grouped according to the exposure histories. The outcome assessment for SPD by scores of 13 or higher on the K6 questionnaire was carried out 3 years after the baseline scores were obtained. Participants were all full-time regular employees of one office of a manufacturing company in Japan. Participants who were being treated for mental disorders, those with SPD and those with missing data on the K6 questionnaire in the baseline survey were excluded from the prospective cohort. Self-reported questionnaire data from 1087 employees who participated in all surveys and answered all questions were analysed. Logistic regression analysis was used to explore the effect of OIJ on SPD. RESULTS: SPD developed in 35 participants. Frequent OIJ exposure was associated with a higher risk for SPD (p for trend=0.002). Of the 1087 participants, 319 (29.3%) experienced a change in OIJ exposure at least once, and 8.6% of subjects experienced such a change twice. These changes in OIJ exposure were more strongly related to SPD than was the frequency of OIJ exposure. CONCLUSIONS: OIJ was associated with SPD onset particularly when the workers were more frequently exposed to it. Moreover, frequent changes in the OIJ exposure were associated with a higher risk for SPD. Because OIJ exposure can change in a relatively short time, considering exposure histories may provide useful information for preventing mental disorders.