The inter-rater and intra-rater reliability analysis of workplace ergonomic risk assessment

Abstract

Observation tools have found wide application in ergonomic assessment of musculoskeletal disorders (MSD) because of their ease of use, ability to be used by multiple users with less specialised training and less operation time. However, their major challenge remains the reliability of their findings. Since MSD is a multidisciplinary problem, there is need for observation tools to be precise when used by practitioners from different professions. This study therefore, investigated the intra-rater and inter-rater reliability of workplace ergonomic risk assessment (WERA) observation tool. Thirteen ergonomics and safety stakeholders, from four different professions were trained and thereafter, independently asked to carry out risk assessment of ten different videos-captured work activities. WERA was used to evaluate the participants’ exposure to six physical risk factors of MSDs in six body regions, so as to determine their risk level. The assessment was repeated after two weeks. The interclass reliability analysis was carried out using the intraclass correlation coefficient (ICC) with the two-way mixed model and absolute agreement as the preferred types. Two of the tasks, tyre extraction and quay crane operation were rated as high risked with an exposure rating greater than 60%, while the remaining eight were medium-risked. The body regions with high probability of MSD exposure were the neck (70%), leg (60%), wrist (60%) and back (50%). Inter-rater reliability (ICC) of the activities by the professionals ranged between 0.97 and 0.99 while intra-rater reliability of the participants ranged between 0.81 and 1.0. The reliability analysis demonstrated consistency among the different professionals using WERA. Therefore,there is a need to urgently redesign the tasks and carry out ergonomic interventions in the work activities assessed.