Abstract: A Case-crossover Study of Transient Risk Factors for Occupational Traumatic Hand Injuries

injuries. Since occupational hand injuries occur as a result of acute exogenous force, most causes of occupational hand injuries are transient risk factors occurring immediately before injury occurs. Triggers can be reasonably defined as preceding causes in causal relationships. When many different causes exist causing the same outcome, the probability that a certain outcome will occur can be reduced by finding predictable causes or removing some causal factors. When examining the causes that result in occupational injuries, causes exist that may not be corrected such as gender . However, causes that can be predicted and prevented to avoid accidents, such as mechanically or physically unsafe states and behaviors, also exist. Finding correctable causes is important to develop preventive measures aimed at reducing occupational acute hand injuries. Case-crossover studies are suitable to evaluate the effect of rapidly changing factors in sudden accidents because each case becomes its own control; thus, confounding factors that occur from differences between individuals, such as age, gender and work experience, can be eliminated. In the medical field, the case-crossover design is used in studies related to injuries from traffic accidents , injuries resulting from drinking or factors triggering acute myocardial infarction and cerebrovascular events. Risk factors affecting occupational acute hand injuries are temporary in many cases and are such that the state of exposure changes over time. These risk factors have short time intervals between exposure and the resultant hand injury. Also, because the effect of an exposure acts temporarily, little carryover effect occurs. The case-crossover design is useful in controlling confounding variables because the design eliminates the effect of variations between individuals, such as work proficiency or past injury. This study was conducted to identify transient risk factors affecting occupational acute hand injuries Abstract: A Case-crossover Study of Transient Risk Factors for Occupational Traumatic Hand Injuries in Incheon, Korea: Won-Jun CHOI, et al. Department of Ocean and Underwater Medicine, Maritime Medical Center, ROK Navy, Korea—Objectives: A casecrossover study was conducted to identify transient risk factors for occupational acute hand injuries. Methods: In total, 98 subjects were recruited from a hospital specializing in occupational accidents and trauma. Patients who had injured fingers, hands or wrists during work were interviewed within 30 days after their accidents. Results: The relative risks for each factor were as follows: 22.9 for unusual or malfunctioning machines (95% confidence interval [CI] 14.4–36.4), 3.3 for wearing gloves (95% CI 1.9–5.7), 5.7 for unusual tasks (95% CI 3.8–8.8), 12.1 for altered work methods (95% CI 8.4–17.6), 4.1 for rushing (95% CI 2.6–6.3), 12.9 for being distracted (95% CI 7.9–20.9), 1.2 for feeling ill (95% CI 0.4–3.6) and 1.0 for working overtime (95% CI 0.6–1.6). Conclusion: The results suggest that some transient risk factors were associated with occupational acute hand injuries. These risk factors are probably preventable, and modifying unsafe or unusual conditions is important to reduce occupational traumatic hand injuries. (J Occup Health 2012; 54: 64–73)