Socioeconomic status, job strain and common mental disorders - An ecological (occupational) approach

Objectives: This study attempted to determine whether an ecological association exists between job strain and common mental disorders at the occupational level and whether the association is a confounding effect of socioeconomic status. Methods: Male occupations from Belgium (N=184) and the United States (US) (N=120) were chosen from the BELSTRESS study (Belgian job-stress study) (1994-1998) and quality of employment surveys (1972-1977), respectively. Age, marital status, socioeconomic indicators, job control (skill discretion and decision authority), psychological demands, supervisory and coworker supports, physical demands, job insecurity, and symptom scales for mental disorders were all aggregated at the occupational level (detailed occupational codes). Job strain was defined as a ratio of psychological demands to job control. Simple correlations, graphic investigations, and multivariate regression analyses were conducted. Results: While job strain was significantly correlated with socioeconomic indicators in the US sample, their covariance was less than 30% in both samples. In the graphic investigations, job strain was orthogonal to all of the socioeconomic indicators. Job strain (both samples), job control (US sample), skill discretion (Belgian sample), and psychological demands (Belgian sample) were associated with mental disorders, after control for the covariates (including socioeconomic indicators). The association of decision authority with mental disorders was relatively weak in both samples. Generally, the associations were stronger in the low or middle socioeconomic group than in the high socioeconomic group. Conclusions: Job strain is associated with common mental disorders at the occupational level, and it is not explained fully in the context of the association between socioeconomic status and mental disorders.