Background. Prior research on work-related factors in the aetiology of psychiatric disorders has been concentrated on job control, job demands and social support. To broaden the view to managerial procedures, we examined whether the extent to which employees are treated with equity in the workplace predicts their mental health. Organizational equity refers to decision-making procedures, which are consistently applied, open, correctable and include input from affected parties (procedural justice). It also refers to respectful and considerate treatment of individuals by supervisors (relational justice).

Method. A cohort of 1786 female hospital employees with no psychiatric disorder at baseline responded to a questionnaire on organizational equity. From the responses, both an individual score and a work unit mean score were assigned to each participant. The outcome was new reports of doctor-diagnosed psychiatric disorders during the 2-year follow-up. Odds ratios and 95% confidence intervals were corrected for clustering of the data.

Results. After adjustment for age and salary, odds ratio of new psychiatric disorders for self-reported low procedural justice was 1·9 (95% CI 1·1 to 3·2). Corresponding odds ratio for low procedural justice, as assessed with work unit mean scores, was 1·7 (95% CI 1·5 to 2·0). These associations remained statistically significant after additional adjustment for mental distress at baseline and job control, job demands and social support. Relational justice did not predict psychiatric disorders.

Conclusion. Research on organizational equity provides new information about potential work-related determinants of mental health. Low procedural justice seems to be an independent risk factor for psychiatric disorders in female employees.