Prior longitudinal studies of negative working conditions and depression generally have used a single exposure indicator, such as job strain, and have required consistent availability of the measure across waves and selection of only those working at all measurement points.
Up to four waves of the Americans' Changing Lives study (1986 to 2001/2) and item-response theory (IRT) models were used to generate wave-specific measures of negative working conditions. Random-intercept linear mixed models assessed the association between the score and depressive symptoms.
Adjusting for covariates, negative working conditions were associated with significantly greater depressive symptoms.
A summary score of negative working conditions allowed the use of all available working conditions measures and predicted depressive symptoms in a nationally representative sample of US workers observed for up to 15 years. Linear mixed models also allowed retention of intermittent workers.