NEWS RELEASE, 12/01/98 Award-winning UC Berkeley study proves that work-related back aches are not "all in your head"

By Robert Sanders, Public Affairs

BERKELEY -- Back injury at work often gets explained - and sometimes dismissed - as a psychological problem. That's because researchers have never been able to prove that the physical demands of the job alone can result in injury to the spine, quite apart from such complications as job dissatisfaction or problems with supervision. Now, in a prize-winning paper, researchers at the School of Public Health at the University of California, Berkeley, have untangled this perplexing issue for one industry - the people who drive buses in San Francisco. They have found that after accounting for all the possible psychosocial causes of back injury, drivers with the San Francisco Municipal Railway (MUNI) still have an elevated risk for injury that can be attributed solely to their physical working conditions, particularly the number of hours on the job. Drivers who worked full-time had more than twice as many back injuries as those who worked part-time. In fact, the risk was almost three times as high for full-timers, raising the question of whether part-time work might be effective in reducing workman's compensation claims. Cable car drivers also had three times more back injuries due to the heavy physical work of moving these historic vehicles. The research, led by Niklas Krause, a physician-epidemiologist and visiting scholar at UC Berkeley, has been chosen in international competition to receive the Swedish Volvo award for 1998, given for excellence in clinical studies. It is being published in the December issue of Spine, the leading international journal in the field. Co-authors are David R. Ragland, a research epidemiologist in UC Berkeley's School of Public Health; June M. Fisher, clinical professor at the University of California, San Francisco; and Leonard Syme, UC Berkeley professor emeritus of epidemiology. "Although we can't generalize to other work environments, we've been able to prove an important principle," said Krause. "We can show that both physical and psychosocial conditions in the workplace play a role in causing back injury." The research also revealed that after accounting for physical work load, a stressful job with high psychological demands, low satisfaction and low supervisor support can cause spinal injury. But it was the clear link between physical work load and injury that had been obscured. Before this, said Krause, people in occupational health could dismiss back injury or intervene in the wrong way. "They could say, 'Oh, it's all in your head,' or 'You just don't get along with the boss.' This has often led to blaming the victim and explaining back-related injury as a problem of oddballs and difficult people." This perspective was given an enormous boost by a 1991 landmark study at a Boeing aircraft plant in Seattle which found that only psychosocial factors - not physical work conditions - were related to back injury. Unfortunately, this finding was probably due to limitations researchers encountered in measuring physical work load in the Boeing study, said Krause. "It's been a nightmare," said Syme, a noted authority on workplace stress and chief adviser on the study. "You have stress on the job, stress at home, relations with supervisors, psychological demands and physical demands - all tied up together. Now for the first time we have been able to sort out these multiple factors and figure out what is really causing the back pain," said Syme. As at Boeing, the Muni driver study followed subjects for several years, providing rarely obtained information on conditions that pertained before and after the injury. Researchers followed drivers onto the buses and watched as they padded their broken-down seats with newspapers or sacrificed their breaks to make up for delays on the route. They learned about psychological and social stresses from several questionnaires given to the 1449 Muni drivers in the baseline study by Ragland, Syme and Fisher, which lasted for three years from 1983 to 1985. For the current study, Krause gained access to difficult-to-obtain records on workman's compensation and discovered that 320 of those 1449 drivers had reported a total of 445 back injuries during the five years of observation. "One driver in five had a back injury and some had more than one. That's a high rate of injury, comparable to the rates for firemen and policemen," said Krause. He said the spinal injuries cost Muni some several million per year in workman's compensation and represent only the tip of an iceberg. About half of the U.S. workforce experiences work-related back pain in any one year, but only a fraction ever report it, he said. The researchers are currently discussing intervention projects with Muni aimed at reducing the number of back injuries. The most obvious suggestion - part-time work - is politically difficult to implement, but the studies have shown that ergonomic problems in the vehicles can be improved, and that Muni can add more bus drivers to reduce time pressures from understaffing, among other changes. One such intervention, called the Ambassador program, is already providing extra drivers and improved working conditions on the Filmore route in San Francisco. In addition, Muni management has purchased new driver seats for many vehicles and has said the company will work with unions and researchers to improve working conditions.