Study of the validity of a job–exposure matrix for the job strain model factors: an update and a study of changes over time
The objectives of the study were to construct a job–exposure matrix (JEM) for psychosocial work factors of the job strain model, to evaluate its validity, and to compare the results over time.
The study was based on national representative data of the French working population with samples of 46,962 employees (2010 SUMER survey) and 24,486 employees (2003 SUMER survey). Psychosocial work factors included the job strain model factors (Job Content Questionnaire): psychological demands, decision latitude, social support, job strain and iso-strain. Job title was defined by three variables: occupation and economic activity coded using standard classifications, and company size. A JEM was constructed using a segmentation method (Classification and Regression Tree—CART) and cross-validation.
The best quality JEM was found using occupation and company size for social support. For decision latitude and psychological demands, there was not much difference using occupation and company size with or without economic activity. The validity of the JEM estimates was higher for decision latitude, job strain and iso-strain, and lower for social support and psychological demands. Differential changes over time were observed for psychosocial work factors according to occupation, economic activity and company size.
This study demonstrated that company size in addition to occupation may improve the validity of JEMs for psychosocial work factors. These matrices may be time-dependent and may need to be updated over time. More research is needed to assess the validity of JEMs given that these matrices may be able to provide exposure assessments to study a range of health outcomes.
KeywordsPsychosocial work factors Job stress Job strain Job–exposure matrix Job title Occupation Economic activity Company size
The authors thank the members of the DARES (French ministry of labour), all the occupational physicians and ‘médecins inspecteurs régionaux du travail’, and all the employees who participated to the SUMER survey and made this study possible. The authors also thank Laure Ngabirano for her help in the check of the data related to occupation and economic activity.
This study was funded by the French National Research Program for Environmental and Occupational Health of ANSES, France (Grant no. EST-2016/1/49).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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