Association of combinations of perceived workplace disagreement and friendliness with long-term sickness absence due to mental disorders among Japanese employees: a one-year prospective cohort study using items from the Brief Job Stress Questionnaire.

OBJECTIVES: In the Brief Job Stress Questionnaire (BJSQ), items A12-A14 assess interpersonal conflict in the workplace. A12 (disagreement) and A14 (friendliness) are typically summed, which implicitly assumes that disagreement is adverse. However, employees who perceive high disagreement in a friendly work environment may be able to voice differing opinions without concern, a pattern consistent with psychological safety, and may form a low-risk group overlooked by summed-score approaches. This study investigated how combinations of perceived disagreement and friendliness are associated with long-term sickness absence (LTSA) due to mental disorders. METHODS: A baseline survey using the BJSQ was conducted among 14,687 employees of a financial services company without LTSA in the previous three years. LTSA and diagnoses during one-year follow-up were obtained from personnel records. Participants were classified into four groups based on positive/negative responses to A12 and A14: high-disagreement and high-friendliness (HD+HF), high-disagreement and low-friendliness (HD+LF), low-disagreement and high-friendliness (LD+HF), and low-disagreement and low-friendliness (LD+LF). Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for LTSA due to mental disorders, using the HD+LF group as reference. Interaction between disagreement and friendliness was also tested. RESULTS: After adjusting for potential confounders, HRs were significantly lower for both the HD+HF group (HR=0.18, 95% CI: 0.07-0.44, p<.001) and the LD+HF group (HR=0.26, 95% CI: 0.14-0.50, p<.001), with overlapping CIs. The interaction was marginally significant but imprecise (HR=4.89, 95% CI: 0.90-26.6, p=.066). CONCLUSIONS: Perceived friendliness in the workplace remained protective against LTSA due to mental disorders, even with disagreement.