Epidemiologic evidence on manual materials handling as a risk factor for back disorders: a systematic review

In this review, epidemiologic evidence on the role of manual materials handling in the occurrence of back disorders was systematically evaluated. Twenty-five publications that provided quantitative data on associations between manual materials handling and back disorders were selected. Study findings were evaluated on the basis of strength of association, consistency in findings and dose–response relations. The methodological quality of each study was assessed to consider the relative value of the findings. Although a considerable number of epidemiologic studies investigated the risk of lifting, only a moderate insight in the dose–response relation between exposure to lifting and occurrence of back disorders was found. Evidence on carrying and on pushing/pulling as risk factor for back disorders was very limited. Only very few quantitative studies were performed and the results of these studies were inconsistent. The amount of evidence on the risk of exposure to combined manual materials handling was only moderate. It was concluded that, based on the criteria applied in this study, epidemiologic evidence for manual materials handling as risk factor of back disorders is present, but largely based on cross-sectional studies with inherent methodological weaknesses. More longitudinal studies need to be performed in which special attention is given to accurate exposure measurements, valid assessment of back disorders, and dose–response relations.