Alternative approaches to analytical designs in occupational injury epidemiology

Abstract

In this paper, we discuss the theoretical framework upon which observational studies of occupational injuries are based. Following a general description of how causal effects are estimated, the challenges faced by researchers working in this area are outlined, with an emphasis on case‐control studies. These challenges include defining the at‐risk period for workers whose tasks change over time and whose hazard period may be very brief, evaluating the underreporting of both exposures and injuries, and considering the effects of multiple injuries per individual on study design and data analysis. We review both the theoretical and practical considerations in the design and conduct of traditional case‐control studies, based on the collection of individual level data, as well as other approaches, such as using information culled from administrative and descriptive databases, and case‐control studies in which the plant or work site is the unit of analysis. The case‐crossover design is also reviewed and its utility for reducing confounding due to differences between individuals by self‐matching is highlighted. While this design has not yet been applied to the work setting, its potential for increasing our understanding of the causes of acute‐onset occupational injuries seems promising. Finally, a variety of hybrid designs are discussed, including combinations of case‐control, case‐crossover, and cohort designs. Am. J. Ind. Med. 32:129–141, 1997. © 1997 Wiley‐Liss Inc.

Transient risk factors of acute occupational injuries: a case-crossover study in two Danish emergency departments

“…This supports findings from other study designs highlighting the importance of, eg, machine safety (5,13). Furthermore, our results indicate that working with broken machinery and materials is more hazardous in high-risk industries than in intermediateand low-risk ones.…”

“…As in several other work injury case-cross-over studies, the same hazard period for all transient risk factors was chosen for our study (18,(2)(3)(4)(5)(6)(7)(8)39). However, the hazard period is likely to vary between different transient risk factors, eg, a Informative pairs include injured persons who were exposed previous workday, but not before the injury and vice versa.…”

“…Injury prevention is most successful if the etiology of an injury is understood so that efforts can be focused more directly (5). Identifying short-term risk factors that…”

The effect of cigarette smoking on musculoskeletal‐related disability

“…The creative linkage of relevant data systems on exposures and outcomes are increasingly being realized as effective and efficient tools for etiologic research [Mittleman et al, 1997;NORA Traumatic Injury Team, 1998]. This cohort study provided insight into one of the potential risk factors for development of disability while adjusting for many potential confounders.…”

The SIMPOC Philippine Survey of Children 2001: A Data Source for Analyzing Occupational Injuries to Children

“…Still, these assumptions about children's time at work may artificially inflate or deflate the denominator for persontime, leading to biased incidence rate estimates. 39 The following example illustrates how the time-related questions from the SOC 2001 are used to compute the number of person-hours a child worked during the reference period (12 months in this case). Consider a child identified as a "seasonal worker" (or, alternatively, one who indicates working during school vacations) who reported that he or she normally worked five to eight hours per day for an average of three days per week during the 12-month reference period.…”