Testing two methods to create comparable scale scores between the Job Content Questionnaire (JCQ) and JCQ-like questionnaires in the European JACE study

Background: Scale comparative properties of "JCQ-like" questionnaires with respect to the JCQ have been little known. Purpose: Assessing validity and reliability of two methods for generating comparable scale scores between the Job Content Questionnaire (JCQ) and JCQ-like questionnaires in sub-populations of the large Job Stress, Absenteeism and Coronary Heart Disease European Cooperative (JACE) study: the Swedish version of Demand-Control Questionnaire (DCQ) and a transformed Multinational Monitoring of Trends and Determinants in Cardiovascular Disease Project (MONICA) questionnaire. Method: A random population sample of all Malmo males and females aged 52-58 (n = 682) years was given a new test questionnaire with both instruments (the JCQ and the DCQ). Comparability-facilitating algorithms were created (Method I). For the transformed Milan MONICA questionnaire, a simple weighting system was used (Method II). Results: The converted scale scores from the JCQ-like questionnaires were found to be reliable and highly correlated to those of the original JCQ. However, agreements for the high job strain group between the JCQ and the DCQ, and between the JCQ and the DCQ (Method I applied) were only moderate (Kappa). Use of a multiple level job strain scale generated higher levels of job strain agreement, as did a new job strain definition that excludes the intermediate levels of the job strain distribution. Conclusion: The two methods were valid and generally reliable.