Abstract
Objectives: Recently, an increasing number of Japanese workers have shown signs of stress. A tool to detect the process of worsening of worker's mental health is urgently needed. In 2006, we found five new factors including "self assessment of one's working worth, fulfillment", "decreased will to work", "fatigue/exhaustion", "insufficient inner reserves", "social relationship" in the Burn-Out Scale for Japanese version using structural equation modeling (SEM) with the parceling technique. Then, we developed a new Mental Health Inventory-5 for Workers (MHI-5) after evaluating 18 well-known assessments of Worker's Stress Methods: The subjects were 228 workers (male 124, female 104, 42±12 years). The study was performed between July and September 2006 using an interview or mailed survey. The following data were collected: 1) Job including overwork, autonomy and aptitude for job, 2) Cognition including negative thinking, idealism (self sacrifice) and anxiety regarding insufficiency, 3) Social Relationship including asking someone for advice, help and communication, 4) Psychosomatic Condition including depressive tendency, neurotic tendency, sleep, appetite and general complaints, and 5) MHI-5. The MHI-5 was constructed of five subscales, that is, "working worth, fulfillment"," decreased will to work", "fatigue/exhaustion", "insufficient inner reserves, and "social relationship", as described above, using a total of 30 questions. In this study, we evaluated the reliability, validity and causal model of our MHI-5. Results: The internal consistency of the MHI-5 was very high (α=0.901). The five subscales correlated with each other. An explorative factor analysis showed that five subscales of MHI-5 were coincidental with the five-factor structure obtained by our previous study. The inventory was strongly correlated with certain important occupational stressors. These findings suggested a high criterion-related validity of MHI-5. Furthermore, SEM analysis using the parceling technique showed a good index of fit in a causal model of MHI-5. Conclusion: We found good reliability, validity and a good index of fit in a causal model of the newly developed MHI-5. We emphasize that our inventory is a good generic screening test for assessing problems in worker's mental health easily and quickly.
