Evaluation of the RAMP Tool’s New Hand Model -Reliability, Usability and Face Validity

Abstract: Hand-intensive work significantly correlates with the increased risks of developing Distal upper-extremity (DUE) Work-related musculoskeletal disorders (WMSDs), such as carpal tunnel syndrome and tendinitis. Many studies have investigated the physical risk factors and their contribution to the occurrence of the DUE WMSDs. These factors include but are not limited to hand force, level of hand movement repetition, and non-neutral hand-wrist postures. Several observational-based risk assessment methods have emerged from these studies to control these risk factors and reduce the DUE WMSDs' development. In this regard, The RAMP Tool's Hand Model (RAMP's HM) has been developed recently by the Ergonomics Division at KTH Royal Institute of Technology as a new model within the RAMP Tool .The aim with RAMP's HM is to fulfill the need for an observational-based, preventive, research-oriented, and systematic method of risk management targeting the elevated risks of DUE occupational injuries associated with hand-intensive tasks. Moreover, the RAMP's HM seeks to investigate and combine a more significant number of ergonomic risk factors than those covered by existing DUE observational-based risk assessment methods. This master's thesis project evaluated the latest prototype of RAMP's HM for reliability, usability, and face validity. A group of ten ergonomists and ergonomics coordinators, all working at Scania AB, had volunteered to participate in this evaluation study. They assessed eight video records of hand-intensive work tasks across various industries using RAMP's HM. The raters assessed the model's inter-rater and intra-rater reliability by evaluating eight video records of hand-intensive work tasks in two assessment sessions, which were separated by a 21-day gap. The ergonomists also used the 2018 ACGIH® Hand Activity Level (HAL)– Threshold Limit Value (HAL Tool) to assess the same video-recorded tasks in the two sessions to evaluate the reliability of RAMP's HM in comparison (the inter-method reliability). Seven of the ten ergonomists volunteered to complete a quantitative questionnaire using a 5-Likert scale to assess the usability and face validity of the new RAMP model. The evaluation showed that the RAMP Tool's Hand Model has fair inter-rater and moderate intra-rater reliability. The reliability test also showed a similar level of reliability for the two methods, with no significant differences between the reliability results of RAMP's HM and HAL. The reliability results of the RAMP's HM may have been adversely influenced by statistical factors, and factors related to the observation process, raters' experience and background, and pre-test training. The categories of the resulting ratings for overall risk levels on the task level using RAMP's HM and the HAL Tool agreed in over 75% of ratings. According to the ergonomists, RAMP's HM is usable; it supports the systematic risk management approach, and their answers indicated that it has been designed in a user-centered way. Furthermore, the evaluation results indicated a strong face validity for RAMP's HM. Raters perceived the new model as a practical tool for systematically managing DUE WMSDs and the corresponding risk factors across various work environments and industries. Based on the results of this study, it is recommended that comprehensive education and practical training on RAMP's HM are provided before conducting further evaluations, i.e., on the complete RAMP 2.0 version. Furthermore, it is recommended to include more participants and tasks in such evaluations. Additionally, it may be valuable to consider using other reliability parameters besides the weighted Cohen's kappa.