Comparison of Strain Index (SI) and ACGIH-HAL in Assessing the Risk of Upper Extremities Disorders and Prediction of Carpal Tunnel Syndrome in Butchers

Background and Objectives: Upper extremities are very vulnerable to work-related musculoskeletal disorders and selecting the best technique for assessing their exposure to ergonomic risk factors is of pivotal importance. This study aimed to compare two techniques of SI and ACGIH-HAL and assess their relationship with carpal tunnel syndrome (CTS) among butchers. Methods: The study population was all butchers in Hamadan, Iran. After observing the activities, the assessments were conducted using both techniques. The severity of CTS syndromes was assessed using Boston questionnaire. The agreement between the techniques was investigated using Kappa coefficient. The association between the risk levels obtained from the techniques with the severity of CTS syndromes were assessed by regression analysis and fixing the effect of personal factors such as age, body mass index, and wrist ratio index. Results: a total number of 152 butchers were evaluated. SI and ACGIH-HAL techniques respectively recognized 76 and 102 cases as low risk (agreement in 69 cases), 40 and 27 cases as moderate risk (agreement in 8 cases), and 36 and 23 cases as high risk (agreement in 18 cases). The Kappa coefficient between two techniques was 0.36 (P<0.001). By fixing the effects of age, body mass index, and wrist ratio index, both techniques had significant association with the severity of CTS syndromes. However, the association between SI and severity of CTS syndrome was higher than that of ACGIH-HAL. Conclusion: SI had a higher estimate of risk than ACGIH-HAL. It seems that the predictive ability of SI for the severity of CTS syndrome is better than that of ACGIH-HAL.