Incorrect Figure Key
Authors: Craig Zwerling, Paul Whitten, Charles Davis, Nancy Sprince
Journal: JAMA (1998)

Our main finding demonstrated a modest association between occupational injuries and preexisting work disabilities.Dr Seelman points out that we excluded 3728 cases and that "without this exclusion, the results are not statistically significant."We excluded these cases because they reported that both the onset of their disability and their occupational injury occurred within the last year.We were unable to determine whether the disability preceded the injury or was a consequence of it.We have now reanalyzed the data including an additional 2806 of the previously excluded cases (using a complex algorithm based on more detailed time categories to establish that the disability preceded the injury).The result showed that after adjusting for occupation, self-employment, and age, occupational injury was still associated with preceding work disability with an odds ratio (OR) of 1.35 (95% confidence interval [CI], 1.19-1.54),essentially the same as the OR of 1.36 (95% CI, 1.19-1.56)reported in our article.Dr Kirchner raises concerns about the definition of 2 key variables, "occupational injuries" and "workers with disabilities."She suggests that by building residual limitation in work ability into these definitions, we introduce confounding.In response, we point out that other studies using other definitions of these key variables found results similar to ours.Elsewhere, we analyzed data from the Health and Retirement Study (HRS), 1 a nationally representative sample of older Americans.The HRS defined occupational injury irrespective of any residual limitation.We found that occupational injuries were associated both with poor hearing (OR, 1.60; 95% CI, 1.11-2.30)and with poor sight (OR, 1.53; 95% CI, 1.11-2.09).In a study of Dutch shipyard workers using audiometric data to measure impaired hearing, Moll van Charante and Mulder 2 found that workers with impaired hearing had an increased risk of occupational injuries (OR, 1.90).The consistency of these results with our NHIS results suggests that measurement bias is not a major problem.We agree that our results for blind and deaf workers were based on small numbers and should be regarded with caution.We reported them to suggest a causal hypothesis.If sensory impairments increase workers' risk for occupational injuries, those workers with the most severe impairments, blind and deaf workers, would have the highest risk of injury.The data, although thin, tend to support this hypothesis.We agree that a complete understanding of disability in the workplace requires studying not only the workers' impairments, but also their work environments and workplace accommodations.Unfortunately, most national databases have not included information on accommodation and the work environment.We look forward to the imminent public release of the NHIS Disability Supplement, 1994 and 1995, 3 which includes detailed work environment information.Such data will allow researchers to develop a more complete picture of the disabling/enabling process recently described in the Institute of Medicine report, Enabling America.