0183 Face validity and inter-rater agreement between expert assessments of occupational mechanical exposures in a lower body job exposure matrix

Abstract

OBJECTIVES: We constructed a lower body job exposure matrix (JEM) based on five experts' assessments of occupational mechanical exposures. The aim of this study was to evaluate the face validity of the rankings of the job groups and the inter-rater agreement between the experts' rankings. METHOD: The JEM cross tabulates the mean of five experts' assessments of daily duration (hours/day) of standing/walking, kneeling/squatting, and whole-body vibration as well as total load lifted (kg/day), and frequency of lifting loads weighing >/=20 kg (times/day) in 121 job groups comprising occupational titles with expected homogeneous exposure patterns. The JEM covers 689 occupational titles, which were considered more than minimally exposed, out of 2227 in the Danish version of the International Standard Classification of Occupations. Weighted kappa statistics were used to evaluate inter-rater agreement on rankings of the job groups for four of these exposures. Two external experts checked the face validity of the rankings of the experts' mean values. RESULTS: The experts' ratings showed fair to moderate agreement (mean weighted kappa values between 0.36 and 0.49). The external experts agreed on 586 of the 605 rankings. CONCLUSIONS: Experts agreed on rankings of the job groups, and rankings based on mean values had good face validity. However, further validation is warranted based on technical measurements or observations. The lower body JEM, which provides exposure estimates free of recall bias, has been applicable in exposure response studies of hip and knee osteoarthritis, inguinal hernia repair, varicose veins, and lumbar disc disorders.