Bouncing back from back pain: Workers' reports can predict disability duration

Back pain is the most common and costly occupational disability in the United States; it is also among the most difficult conditions to diagnose. Using data compiled from five employers in 37 states, researchers at the W. P. Carey School of Business have been trying to unravel some of the mysteries of back pain and disability. One important conclusion: Overall health — especially mental health — appears to have a lot to do with how successful a worker is at resuming his or her job after a bout of back pain.

Back pain is the most common and costly occupational disability in the United States. Billions of dollars are lost each year because of work time lost to back pain. Back pain is also among the most difficult conditions to diagnose. Because only about 5 percent of cases can be detected with conventional imaging procedures, clinicians attempting to diagnose and treat back pain usually must rely on what patients tell them about the condition.

Researchers at the W. P. Carey School of Business have been trying to unravel some of the mysteries of back pain and disability. Using data compiled from five employers in 37 states, the researchers have been looking for links between reports from back pain sufferers about their condition and patterns of time lost from work. One important conclusion: Overall health — especially mental health — appears to have a lot to do with how successful a worker is at resuming his or her job after a bout of back pain.

"You might think that would be irrelevant when you are talking about back pain," said Marjorie Baldwin, director of the School of Health Management and Policy. "But there is a significant relationship between how individuals respond to back pain mentally and emotionally and their ability to return to sustained employment."

Another important factor, the researchers discovered, is how capable back pain sufferers feel about performing simple tasks like climbing a flight of stairs, getting up from a chair, and walking a quarter mile. Workers who scored high on a test of readiness to perform those activities were less likely to experience long or repeated spells of work disability.

"There is a logic to that because many times the determination of whether somebody is going to return to work or the duration of work absence is based on a match of their ability to perform some of the activities and the demands of the job," said William G. Johnson, professor of biomedical informatics and director of the Center for Health Information and Research at the School of Computing and Informatics, Ira A. Fulton College of Engineering.

Surveying sufferers of back pain

In addition to Baldwin and Johnson, the research team included Richard J. Butler, an economist at Brigham Young University and Pierre Côté — senior scientist at University Health Network Rehabilitation Solutions, Toronto Western Hospital and associate professor at the Dalla Lana School of Public Health, University of Toronto. They reported their findings in a recent paper entitled, "Self-reported measures as predictors of return-to-work outcomes in occupational back pain."

Data for the study came from the Arizona State University Healthy Back Study, a collection of data and analyses of reports of employees who filed workers' compensation claims for back pain between January 1999 and June 2002. The study population included nearly 200,000 workers from five employers — America West Airlines, American Medical Response, Maricopa County in Arizona, Marriott International, and The Earthgrains Co., now part of Sara Lee Corporation Baking Division.

Whenever an employee from one of these companies filed a compensation claim for back pain, a researcher from the study team contacted and interviewed the employee. Follow-up interviews were conducted at six months and again at 12 months. Three main assessments — all self-reported measures of back pain and its consequences — were administered to the injured workers. One measure is a simple pain intensity question, which asks workers to rank their pain on a scale of 100.

The question is routinely asked in doctors' offices and hospitals to people experiencing pain. A second measure, the Roland-Morris Disability Scale, questions individuals on their ability to perform basic functions, including walking, standing and other activities typically affected by back pain.

A third measure, called the SF — for Short-Form — 12, measures in 12 questions individuals' assessments of their physical and mental health-related quality of life. After compiling the results of these measures, which were administered around the time the workers filed the compensation claims, the researchers tracked the progress of the individuals to see when they returned to work and whether they stayed on the job.

Links between pain, lost time, and health

The researchers found at least some correlation between each measure of back pain and success at returning to work. In other words, workers who reported more pain, less ability to perform basic functions, and poorer general mental and physical health were more likely to lose time from work. Said Baldwin, "All of the self-reported severity measures were correlated with return-to-work outcomes when we follow workers even as long as one year."

But some measures were more closely correlated than others, the researchers found. Pain intensity was a good predictor of whether a person would lose time from work in the days and weeks immediately after an onset of back pain but less accurate six months or a year later. The Roland-Morris test of functional abilities was a better predictor of longer term employment patterns.

According to Johnson, these results make sense since severe, debilitating pain tends to be short-term, but recurring and low level pain tends to stay with back pain sufferers. "A lot of people with back pain will tell you that they are never completely pain free or that it's periodic or recurrent, but it's not disabling in the sense that they have to take off work or can't do their household chores," Johnson said.

The short-form test of overall health — and especially the mental health portion — were the best predictors of return to work outcomes, the researchers found. Workers whose answers indicated a poorer state of mental health were among those likely to have the poorest employment outcomes. According to Baldwin, this finding could have important implications for treatment of people with back pain.

"Perhaps clinicians need to consider if a worker suffering from back pain is depressed or if the worker has fears about returning to work because of the possibility of re-injury," said Baldwin. "Perhaps more needs to be addressed than just treating the pain."

Identifying the most difficult cases

Roughly 20 percent of workers' compensation claims are responsible for 80 percent of the system's costs. According to Baldwin, treating mental health problems early could have many benefits for employees, employers, and the system as a whole.

"If we can identify early in the onset of back pain those cases that are likely to be chronic and impose high costs on the system — and if we can intervene early on to address whatever their issues may be — that could reduce costs to the system, help to produce stable employment, and improve outcomes," she said.

Johnson said the study is important because it looks at real world experiences of workers with back pain, which has proven to be such an elusive ailment to diagnose and treat. "People have done a lot of work on back pain in controlled kinds of settings where one group of people gets one set of therapies and another gets another set of therapies," he said. "This study really provides a look at what happens day to day in the workplace with people with back pain."

Bottom Line:

• Back pain is the leading cause of time lost from work in the United States. The ailment is difficult to diagnose and treat, and doctors usually have to rely on patient self-reports to assess the severity of the condition.
• An extensive, long-term study of individuals who lost time from work because of back pain found strong links between overall mental health and return-to-work outcomes.
• Pain intensity reports by patients were good indicators of whether patients were likely to return to work shortly after an onset of back pain, but were not closely correlated with return-to-work months later.
• Whether patients said they could perform basic functions — such as standing, walking, and sitting - was a reasonably strong indicator of whether a person would return to work.
• By determining factors associated with work time lost because of back pain, it might be possible to identify and treat patients who have a high risk of long-term disability.