Researchers say study may aid efforts to prevent long-term disability

A wide range of factors, including variables related to health care and job characteristics, affects the risk of long-term disability for workers with back injuries, according to a recent study. However, researchers said that the findings may help in targeting workers for special attention to prevent disability.

In the report, issued in a recent issue of Spine journal, researchers from the University of Washington in Seattle performed interviews with more than 1,800 individuals who submitted a workers' compensation claim for lost work time an average of three weeks after experiencing a back injury on the job. A wide range of factors -- including medical, job-related and psychological factors -- were analyzed as possible risk factors for disability at one year after the injury.

Judith A. Turner, lead author of the study, said that, not surprisingly, workers with more severe back injuries were more likely to be on disability after one year. Employees with pain spreading down into the leg -- indicating involvement of the spinal nerve roots, or radiculopathy -- were at particularly high risk.

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Researchers also found that disability risk was also higher for workers who rated their initial disability higher, who had pain at more sites, and who had previous injuries resulting in more than one month off work. Another significant predictor was the specialty of the first doctor seen after the back injury. Workers who saw a chiropractor were less likely to be disabled at one year, the study found.

Certain job characteristics also affected disability risk. Risk was lower when employers offered accommodations (such as light duty) for workers recovering from back injuries. In contrast, risk was higher for workers who rated their jobs as "very hectic."

The researchers combined all of the significant factors into a statistical model for use in predicting which employees were at the highest risk of long-term disability after a back injury. Turner said the model was 88 percent accurate in identifying workers who would and would not be disabled after one year.

Understanding early risk factors is key. Researchers said that work-related back injuries are very common. Although only a small fraction of employees with back injuries develop long-term disability, Turner said this group accounts for most of the costs related to back pain. Knowing the early risk factors for long-term disability could help in understanding why some workers become disabled and, more importantly, allow them to be targeted for interventions to prevent disability, she said.

Turner said the study is the largest so far to examine risk factors for chronic disability after back injuries. Although more severe back injuries are one important factor, other risk factors are significant independent of injury severity, she said.

"This confirms clinical impressions that patients with similar examination and imaging findings vary in pain and disability outcomes, likely because of factors other than biologic ones," Turner said.

Researchers said that current approaches to chronic pain emphasize the interrelationships between biological and psychological factors. However, in the new study, Turner said that most of the psychological factors thought to contribute to chronic pain were not significant risk factors for disability. The researchers called for expanded approaches to prevention and treatment that will account for the many different factors that can affect disability, including "health care provider, employer and family responses, and work and economic factors."

January 12, 2009

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