Validation of the OCRA Checklist Score as Predictive of the Occurrence of UL-WMSDs in Workers Exposed to Manual Repetitive Tasks

ISO 11228–3 and ISO TR 12295 recommend the OCRA Checklist as a useful method for screening exposure to manual repetitive tasks. The aim of this study is to define forecasting models for the expected prevalence of UL-WMSDs in groups of exposed workers based on the OCRA Checklist scores. A database of 11,734 workers divided into 30 groups featuring different exposure levels and different prevalences of UL-WMSDs was analyzed. The association between the independent variable “Checklist score” (CK) and the dependent variable “% of workers with UL-WMSDs” (PA) was researched: a convincing association (R2 = 0.86) resulted from the linear regression equation PA = 0.742(±0.055) x CK, which may be used (within defined limits) as a model for forecasting the occurrence of UL-WMSDs based on the OCRA Checklist score. By using pre-established OCRA Checklist key-values, macro-groups with different exposure levels were created and the Prevalence Odds Ratio (POR) of each group was computed versus the “non-significant exposure” group. The POR for “borderline”, “low”, “medium” and “high” exposure groups was respectively 2.18, 2.77, 4.36 and 3.78. These results confirm the overall effectiveness of the current classification of the OCRA Checklist scores, while also suggesting that an OCRA Checklist score of 16 should be the cutoff for identifying low and medium exposure.