Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3447.

Adviser: Stanislav V. Kasl.

Research in the occupational setting on harmful psychosocial factors is not as plentiful as research on physical agents. Changes in the workplace to work faster, have fewer workers and produce more may intensify the role of psychosocial risk factors in the etiology of disease. Few studies have used objective ratings to measure psychosocial risk factors and heavy industrial workers have not been studied. This retrospective cohort study evaluates the effect of psychological demand and decision latitude (control) on depression and ischemic heart disease (IHD) diagnosis in a cohort of heavy industrial workers.

Two disease-free cohorts of active hourly employees from eleven United States ALCOA plants between January 1, 1996 and December 31, 2003 were studied. Both used a 2 year run-in period to exclude prevalent cases. Analyses used logistic and Cox Proportional Hazards regression to model the effect of tertiles of demand and control exposure on depression or IHD diagnosis over a six year period (1998 to 2003). The depression free cohort consisted of 7,566 workers. Psychological demand had a significant positive association and low control a significant protective effect on risk of depression, however significance was lost with adjustment for plant location. The ischemic heart disease free cohort consisted of 7,478 hourly workers. Moderate psychological demand increased risk and lower level of control decreased risk of IHD diagnosis, but significance was lost with adjustment. Effects of interaction terms for demand and control were similar to main effects for both outcomes, with terms losing significance with adjustment.

Results suggest objectively measured psychological demand and control are not significant independent predictors of depression or IHD diagnosis in the workers studied. Objective measures of the psychosocial work environment may differ from subjective measures, and may be superior to self report of exposure given the potential for bias, particularly with study of depression. There may also be differences in the effects of psychosocial exposure in heavy industrial workers as compared to other workers. Future research on the relationship of subjective and objective factors specific to job and location may be important in understanding the role of psychosocial factors on depression and IHD outcomes.