NOIRS 1997 Abstracts of the National Occupational Injury Research Symposium 1997. Washington, DC: National Institute for Occupational Safety and Health, 1997 Oct; :7-8
To identify risk factors for work-related injury on the Denver International Airport construction project, which generated over 31 million person-hours, employing 32,000 workers from 769 companies to complete 2,843 contracts. We obtained workers' compensation claims data from an administrative database established under the project's owner-controlled insurance plan, which covered all on-site employees and provided on-site medical care through designated providers. We calculated injury rates by contract and over contract strata of interest by linking claims data with employee demographic information, company and contract characteristics, and contract payroll. We determined that injury rates among contracts held by the same company were independent using generalized estimating equations, enabling us to examine contract-specific factors in relation to total injuries, lost-work-time (LWT) injuries, and non-LWT injuries in Poisson regression models. To control for inherent risk of work in the model, we included expected loss rates (ELRs), which we calculated for contracts using Colorado-specific ELRs provided by the National Council on Compensation Insurance for each job classification. We used logistic regression to determine the association between LWT and non-LWT injuries on a contract level, controlling for person-hours at risk and ELRs. Injury rates were highest during the first year of construction, at the beginning of contracts and among older workers. Risk for total and non-LWT injuries was elevated for building construction contracts, contracts for special trades companies (SIC 17), contracts with payroll over $1 million and those with overtime payroll greater than 20 percent. Risk for LWT injuries, on the other hand, was increased for site development contracts and contracts starting in the first year of construction. Large companies (250+ employees) had significantly lower risk for all injuries. Contracts experiencing one or more minor injuries were four times as likely to have at least one major injury [OR=4.0, 95% CI(2.9,5.5)]. Our finding of increased risk of LWT injury for contracts starting in the first year of the project suggests that enhancement of the project's safety infrastructure during the second year of construction was effective in reducing serious work-site injuries. The absence of correlation between injury rates among contracts belonging to the same company suggests that targeting of safety resources at the level of the contract may be an effective approach to injury prevention. Interventions focused on contracts with considerable overtime work, contracts of special trades companies (SIC 17), and those belonging to small and mid-sized companies may yield reductions in injury rates. Furthermore, efforts to provide adequate site-specific training to workers new to a construction site or new to a contract may also reduce injury burden on large construction sites. The joint occurrence of minor and major injuries on a contract level suggests that surveillance of minor injuries may be useful in identifying opportunities for prevention of major injuries.