Socioeconomic inequalities in health in the working population: the contribution of working conditions

BACKGROUND: The aim was to study the impact of different categories of working conditions on the association between occupational class and self-reported health in the working population. METHODS: Data were collected through a postal survey conducted in 1991 among inhabitants of 18 municipalities in the southeastern Netherlands. Data concerned 4521 working men and 2411 working women and included current occupational class (seven classes), working conditions (physical working conditions, job control, job demands, social support at work), perceived general health (very good or good versus less than good) and demographic confounders. Data were analysed with logistic regression techniques. RESULTS: For both men and women we observed a higher odds ratio for a less than good perceived general health in the lower occupational classes (adjusted for confounders). The odds of a less than good perceived general health was larger among people reporting more hazardous physical working conditions, lower job control, lower social support at work and among those in the highest category of job demands. Results were similar for men and women. Men and women in the lower occupational classes reported more hazardous physical working conditions and lower job control as compared to those in higher occupational classes. High job demands were more often reported in the higher occupational classes, while social support at work was not clearly related to occupational class. When physical working conditions and job control were added simultaneously to a model with occupational class and confounders, the odds ratios for occupational classes were reduced substantially. For men, the per cent change in the odds ratios for the occupational classes ranged between 35% and 83%, and for women between 35% and 46%. CONCLUSIONS: A substantial part of the association between occupational class and a less than good perceived general health in the working population could be attributed to a differential distribution of hazardous physical working conditions and a low job control across occupational classes. This suggests that interventions aimed at improving these working conditions might result in a reduction of socioeconomic inequalities in health in the working population.