Transient risk factors for acute traumatic hand injuries: a case-crossover study in Hong Kong

Objectives: To identify the remediable transient risk factors of occupational hand injuries in Hong Kong in order to guide the development of prevention strategies. Methods: The case-crossover study design was adopted. Study subjects were workers with acute hand injuries presenting to the government Occupational Medicine Unit for compensation claims within 90 days from the date of injury. Detailed information on exposures to specific transient factors during the 60 minutes prior to the occurrence of the injury, during the same time interval on the day prior to the injury, as well as the usual exposure during the past work-month was obtained through telephone interviews. Both matched-pair interval approach and usual frequency approach were adopted to assess the associations between transient exposures in the workplace and the short-term risk of sustaining a hand injury. Results: A total of 196 injured workers were interviewed. The results of the matched-pair interval analysis matched well with the results obtained using the usual frequency analysis. Seven significant transient risk factors were identified: using malfunctioning equipment/materials, using a different work method, performing an unusual work task, working overtime, feeling ill, being distracted and rushing, with odds ratios ranging from 10.5 to 26.0 in the matched-pair interval analysis and relative risks ranging between 8.0 and 28.3 with the usual frequency analysis. Wearing gloves was found to have an insignificant protective effect on the occurrence of hand injury in both analyses. Conclusions: Using the case-crossover study design for acute occupational hand injuries, seven transient risk factors that were mostly modifiable were identified. It is suggested that workers and their employers should increase their awareness of these risk factors, and efforts should be made to avoid exposures to these factors by means of engineering and administrative controls supplemented by safety education and training.