Validation of a Low-Back Disorder Risk Model in a Prospective Study of Ergonomic Interventions into Manual Materials Handling Jobs

Abstract

Few tools used to evaluate the low-back disorder (LBD) risk of manual materials handling (MMH) tasks have assessed their predictive ability. Only valid and accurate tools can reliably determine if an ergonomic intervention will reduce injury. This study evaluated how well a LBD Risk model predicted LBD rate changes of modified jobs. A prospective cohort was used to study 36 repetitive, MMH jobs (32 having had an ergonomic intervention and four comparison jobs having no such change). Employees' trunk motions and work place factors were observed pre- and post-intervention, and the jobs' LBD rates were recorded for these periods. Results indicated a significant correlation between changes in the jobs' predicted LBD Risk values and changes in their actual LBD rates. Linear and Poisson regression models predicted a change in a job's LBD rate and the number of LBDs, respectively, as a function of the job's risk change. This prospective study also showed which ergonomic interventions reduced the jobs' mean LBD rates. This study supports use of the LBD Risk model to accurately assess a job's potential to produce LBDs.