title: Validity test of the IPD-Work consortium approach for creating comparable job strain groups between Job Content Questionnaire and Demand-Control Questionnaire.
abstract: OBJECTIVE
  This study aims to test the validity of the IPD-Work Consortium approach for creating comparable job strain groups between the Job Content Questionnaire (JCQ) and the Demand-Control Questionnaire (DCQ).
  
  
  METHODS
  A random population sample (N = 682) of all middle-aged Malmö males and females was given a questionnaire with the 14-item JCQ and 11-item DCQ for the job control and job demands. The JCQ job control and job demands scores were calculated in 3 different ways: using the 14-item JCQ standard scale formulas (method 1); dropping 3 job control items and using the 11-item JCQ standard scale formulas with additional scale weights (method 2); and the approach of the IPD Group (method 3), dropping 3 job control items, but using the simple 11-item summation-based scale formulas. The high job strain was defined as a combination of high demands and low control.
  
  
  RESULTS
  Between the 2 questionnaires, false negatives for the high job strain were much greater than false positives (37-49% vs. 7-13%). When the method 3 was applied, the sensitivity of the JCQ for the high job strain against the DCQ was lowest (0.51 vs. 0.60-0.63 when the methods 1 and 2 were applied), although the specificity was highest (0.93 vs. 0.87-0.89 when the methods 1 and 2 were applied). The prevalence of the high job strain with the JCQ (the method 3 was applied) was considerably lower (4-7%) than with the JCQ (the methods 1 and 2 were applied) and the DCQ. The number of congruent cases for the high job strain between the 2 questionnaires was smallest when the method 3 was applied.
  
  
  CONCLUSIONS
  The IPD-Work Consortium approach showed 2 major weaknesses to be used for epidemiological studies on the high job strain and health outcomes as compared to the standard JCQ methods: the greater misclassification of the high job strain and lower prevalence of the high job strain.
authors.affiliation: University of California, Irvine, United States of America (Center for Occupational and Environmental Health). b.choi@uci.edu.
authors.forename: Bongkyoo
authors.initials: B
authors.lastname: Choi
authors.affiliation: University of California, Irvine, United States of America (Center for Occupational and Environmental Health). kohhj@yonsei.ac.kr.
authors.forename: Sangbaek
authors.initials: S
authors.lastname: Ko
authors.affiliation: Lund University, Malmö, Sweden (Social Medicine and Global Health).
authors.forename: Per-Olof
authors.initials: PO
authors.lastname: Ostergren
mesh_terms: D004812:Epidemiologic Methods; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007389:Internal-External Control; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D009784:Occupational Diseases / Q000175:diagnosis / Q000453:epidemiology*; D012680:Sensitivity and Specificity; D013315:Stress, Psychological / Q000175:diagnosis / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D016526:Workload
keywords: Malmö; epidemiological studies; misclassification; scoring methods; sensitivity; specificity