Technological developments have improved safety standards in workplaces, but workers around the world still continue to lose their lives and limbs. Amputations at work are rare, yet preventable traumatic injuries that have psychological, physical, and economic implications for the injured worker. Hazardous machines are a known etiological factor that leads to amputations at work.
The magnitude and nature of a problem needs to be understood before designing and implementing preventive interventions. The underreporting of traumatic injuries at work, such as amputations, remains a global challenge, underscoring the need for robust surveillance systems. Better surveillance systems will in turn yield sound epidemiological data to design and implement preventive interventions.
The four papers included in this thesis share a common goal of informing the development of effective preventive interventions and enhancing surveillance mechanisms to reduce the risk of work-related upper-extremity amputations.
This thesis first reviews the principal theories and contemporary definitional discourse in the field of workplace injury prevention. Thereafter, four studies that constitute this thesis are presented. The first two papers concern the assessment of hazardous machines that cause traumatic injuries, such as amputations, and evaluation of injury prevention intervention based on studies in Minnesota. The next two papers address the issues of the epidemiology and surveillance of work-related upper-extremity amputations based on studies in Norway.
Specifically, Paper I presents the baseline findings of a randomized controlled intervention study on machine safety conducted in Minnesota. Paper II summarizes the results of a randomized controlled intervention study on improving machine safety and related safety programs. Paper III reports the results of a study on the epidemiology of work-related upper-extremity amputations in Norway. Paper IV concerns the surveillance of work-related upper-extremity amputations in the Norwegian manufacturing sector.
Study in Minnesota (Papers I and II)
Materials and Methods
The study in Minnesota, United States (2002-2008), is based on data on the risk of traumatic injuries in general and amputations in particular attributable to hazardous machines. The data were collected from metal-working businesses using validated checklists before and after the application of an injury prevention intervention. The outcome of interest in this study was the level of safety of metal fabrication machines with regard to their compliance to best machine-guarding practices. The data are essentially measures of worker exposure to hazardous machines. In addition to the levels of safety of the machines, data on organizational variables, such as the presence or absence of safety committees, unionization, the presence of health and safety programs, and training, were also collected. Based on these data, each business received a machine score and shop safety score.
The 40 businesses that participated in this study were randomly assigned to two groups after the baseline measures were taken. Each group comprised 20 businesses. One group (n = 20) included worker and management representatives, and the other group included only management representatives (n = 20). The worker-management group received the full intervention that included a report based on the baseline evaluations of machine safety and health and safety programs in their businesses, including a compact disk (CD) with resource and training material. Additionally, this group was offered four training sessions. The management-only group received a minimal intervention that included the report based on the baseline evaluations and a CD with resource and training material. Of these 40 businesses, three were lost to follow-up. Thus, a total of 37 businesses were followed-up. The worker-management group and management-only group comprised 19 and 18 businesses, respectively
During the baseline measurement, a total of 824 machines were evaluated in 40 businesses. Overall, 55% of the items that addressed guarding on the machines were present. No single machine complied with all of the critical safety requirements across the 40 businesses. The businesses with safety committees had better scores than those without safety committees. The baseline mean-machine scores were 63% in the workermanagement group and 64% in the management-only group. The mean shop safety scores were 66% and 64% for the worker-management and management-only groups, respectively. The mean machine scores significantly improved over baseline at follow-up by a similar amount (4-5 points) in each of the intervention groups. Similar changes were also observed in shop safety scores in both groups, but were not statistically significant. We did not observe differences in the magnitude of change in either the shop safety or machine safety scores between the two groups.
Study in Norway (Papers III and IV)
Materials and methods
The two studies conducted in Norway utilized surveillance data on upper-extremity amputations registered in the Norwegian Labour Inspection Authority (NLIA) Registry of Work-Related Injuries (RWI) and Association of Norwegian Private Insurance Companies Registry of Occupational Injuries (ANPIC). The first study was descriptive and characterized the epidemiological profile of upper-extremity amputations in Norway in 2007. The second was a retrospective study that estimated the annual number of amputations over a 10-year period (1998-2007) in the manufacturing sector, utilizing a two-source capture-recapture method.
The descriptive study that utilized surveillance data in Norway was based on injuries reported to the RWI in 2007. One hundred forty-nine upper-extremity amputations were reported in 2007. The estimated annual incidence of upper-extremity amputations was 6/100,000 workers. Males aged 20-24 years had the highest incidence rates. A majority of the amputations (n = 111) were clustered in businesses with 49 or fewer employees. The incidence was highest in businesses with 1-9 employees. Manufacturing accounted for 36% of the amputations. Fingers were the most frequently amputated body part.
The capture-recapture study estimated the number of amputations within the manufacturing sector for the 10-year study period (1998-2007). The two sources utilized in this study were the NLIA and ANPIC injury registries. We estimated an annual incidence that ranged from 21 to 62 per 100,000 workers during the study period. Our findings suggest that the undercounting of amputations reported to the NLIA registry varied from a minimum of 16% to a maximum of 58% during the study period.
Machines, particularly in the manufacturing sector, remain a source of hazardous exposure that can lead to traumatic injuries, such as amputations. The presence of safety committees may help reduce the risk of amputations caused by machines. Amputations at work are rare events and remain underreported in national surveillance systems in Norway. Establishing robust surveillance systems that may provide reliable epidemiological data for designing effective preventive interventions is critical.||nb_NO