Do psychosocial work factors and social relations exert independent effects on sickness absence? A six year prospective study of the GAZEL cohort.

STUDY OBJECTIVES The objective of this prospective cohort study was to determine whether psychosocial work characteristics and social relations exert independent effects on the incidence of sickness absence in a population of middle aged French employees over six years of follow up. DESIGN This study included 9631 men and 3595 women participating in the French GAZEL cohort. Social relations (social networks, personal social support, and social relations satisfaction) were measured in 1994 by self report. Psychosocial work characteristics (decision latitude, psychological demands, and social support at work) were ascertained in 1995. Sickness absence data were collected independently. The authors studied the incidence of short (>7 days), intermediate (7-21 days), and long (>21 days) spells of absence from 1995 to 31 December 2001. Rate ratios associated with psychosocial exposures, adjusted on sociodemographic characteristics, and health behaviours, were calculated by means of log-linear Poisson regression. SETTING A cohort of 20000 employees of France's national gas and electricity company (the GAZEL study). MAIN RESULTS Among men and women, levels of decision latitude and personal social support below the median predicted 17% to 24% increases in absence rates. Low satisfaction with social relations and low social support at work lead to a 10% to 26% excess in sick leaves among men. No interactive effects were found between the variables under study. CONCLUSIONS The quality of the work environment and of social relations affect sickness absence over an extended period of follow up. This study supports the hypothesis of independent, not interactive effects.