JCQ scale reliability and responsiveness to changes in manufacturing process

Background The job content questionnaire (JCQ) was administered to automobile manufacturing workers in two interviews, 5 years apart. Between the two interviews, the company introduced substantial changes in production technology in some production areas. The aims were: (1) to describe the impact of these changes on self-reported psychosocial exposures, and (2) to examine test-retest reliability of the JCQ scales, taking into account changes in job assignment and, for a subset of workers, physical ergonomic exposures as assessed through field observations. Methods The study population included 790 subjects at the first and 519 at the second interview, of whom 387 were present in both. Differences in demand and control scores between interviews were analyzed by Wilcoxon matched-pairs signed-rank test. Test-retest reliability of these scales was evaluated by the intraclass correlation coefficient (ICC) and the Spearman's p coefficient. Results The introduction of more automated technology produced an overall increase in job control but did not decrease psychological demand. The reliability of the control scale was low overall but increased to an acceptable level among workers who had not changed job. The demand scale had high reliability only among workers whose physical ergonomic exposures were similar on both survey occasions. Conclusions These results show that 5-year test-retest reliability of self-reported psychosocial exposures is adequate among workers whose job assignment and ergonomic exposures have remained stable over time.