Objectives: To develop a job exposure matrix (JEM) cross-tabulating work related physical loads to the lower extremities with all relevant occupational titles in the International Standard Classification of Occupations (ISCO). The intention was to enable population
studies of risk of hip and knee osteoarthritis using independent exposure assessments.
Methods: A total of 121 homogeneous exposure groups (HEG) were constructed comprising all Danish ISCO occupational titles. Each HEG was allocated the mean score of 5 experts’ ratings of daily duration (hours) of: standing/walking , sitting, kneeling/squatting, and wholebody vibration. Total weight lifted per day (kg) and frequency of lifting burdens weighing 20 kg or more were assessed as well. Differences between mean scores and each individual expert’s ratings were plotted to evaluate systematic over- or underreporting by any one of the experts. Two external experts checked their agreement with the rankings of HEGs based on mean scores.
Results: A two-dimensional JEM of physical work loads to the lower extremities covering all relevant Danish ISCO codes was constructed and reported with English ISCO codes. Experts showed considerable variation in their assessments although no single expert rated exposures systematically above or below the mean scores. The two external experts agreed on 707 of 726 rankings according to experts’ mean.
Conclusion: A JEM based on expert ratings of exposures in HEGs was established. Experts showed considerable variation in their scores, but ranking of HEG based on mean scores, was in accordance with the opinion of external experts. Thus, the JEM will be suitable for specific exposure-response analysis, although the absolute values should be further validated.