About-face: Major study now says back belts do work, and work well
Findings contradict all previous research
The debate over the usefulness of back support belts has taken a dramatic turn, with new research suggesting that the belts not only work, they work really well. Just as occupational health professionals were beginning to convince employers the belts were a faddish waste of money, there may be reason to start urging more use of back support belts.
Though it is only a single study up against many showing the belts don’t work, the new research is particularly convincing for several reasons. First, the study involved a large cohort of The Home Depot workers who performed strenuous activities. Second, the positive effects of using the back belts was far from marginal. The effects were so dramatic that the researchers say they rarely have seen such definitive results from an epidemiological study. And third, the research was completely free of any back-belt manufacturer sponsorship or involvement.
The news comes out of the University of California-Los Angeles School of Public Health, where epidemiologist David L. McArthur, PhD, MPH, and other researchers studied the workplace injury history of 36,000 workers for The Home Depot over a six-year period.1 They found that the number of low-back injuries fell by about one-third after the company imposed a consistent policy on belt use.
"When the study began, those of us involved suspected the effect would be very weak, if at all," McArthur tells Occupational Health Management. "In finding these results, we went back through every single number to be sure we did the computations correctly, because the results are startling."
High degree of confidence in the results
Previous research concerning the effectiveness of back belts consisted mostly of much smaller studies, and the research in favor of back belts was almost nonexistent. That led several professional organizations to issue statements in recent years expressing skepticism, if not outright disbelief, about the effectiveness of the increasingly popular belts. The tide seemed to have turned decisively against back belts, but the California research may change that because of the magnitude of its results. The conclusion of the new study is far more definite than any of the previous studies.
The results are so reliable because of the scope of The Home Depot study, McArthur explains. Researchers studied 101 million person-hours worked by 36,000 employees, with access to every employee’s work history, the actual hours spent on the job, and what jobs they were doing. Those who used back belts showed 34% fewer low-back injury rates compared with those who did not.
"Epidemiological studies that find a 34% change in anything are fairly rare, so we’re looking at something that is a pronounced effect," McArthur explains. "This is a sizable step down in the rate of injury, not something that would happen at random. It if it were a 3% or 4% reduction, that would cause a question of confidence. With a 34% reduction, we can be very confident."
Improvements seen in all segments
The decreased back injuries were seen across all lines at The Home Depot, though the effect was more pronounced with some subgroups than with others. Workers in the youngest set, those aged 25 or younger, suffered 43.8 low-back injuries per million hours without back belts, but only 21.7 injuries per million hours with back belts. That is a prevention rate of 50.5%. Those aged 25 to 34 had a less pronounced but still substantial benefit, with 26 injuries per million hours without belts and 20.2 injuries per million hours with belts, a prevention rate of 22.3%.
The beneficial effect was different for men and women also. For men, the rate of injuries was 35.9 per million hours without belts and 22.9 per million hours with belts, a prevention rate of 36.2%. For women, the rate of injuries was 19.2 per million hours without belts and 14.6 per million hours with belts, a prevention rate of 24%.
The difference in prevention rates probably is the result of several different factors other than the use of back belts, McArthur says. A large contributor would be the "self-selection" of workers out of jobs that require a lot of strenuous labor. Simply because fewer women, for instance, choose to do heavy labor, the prevention rate will be lower when one looks at the entire pool of women employed by a company.
"Note that the men’s injuries with back support is still higher than women without support," McArthur says. "You just don’t see many elderly women doing heavy lifting, so that affects the overall results. There is a beneficial effect for women, just not as pronounced as for men."
Results not applicable to all workplaces
Though McArthur says he is certain that back belts are beneficial for The Home Depot workers, he cautions that the study results are not entirely applicable to every other workplace. Because so many factors are involved in causing and preventing low-back injuries, a workplace would have to be almost identical to The Home Depot to expect the same results. However, an employer would not have to get the same 34% reduction to be happy with the return on purchasing belts, and McArthur concedes some substantial degree of prevention is likely even in dissimilar workplaces.
The study did not attempt to identify precisely how the back belts reduced injuries, and that has been another contention in the debate over back belts. Some proponents have argued that the chief benefit of back belts may come from the "reminder effect." In other words, the belt does nothing physiologically but acts as a psychological prompt to remind the worker to lift safely. Others contend that the belt creates physiological changes that reduce the risk of injury. Still more researchers contend that the benefit actually comes from the training in proper lifting techniques that often accompanies belt use. Detractors have argued there is no evidence for any of those claims, and the belts actually encourage workers to lift more than a safe amount. (See p. 16 for a summary of research discounting the benefits of back belts.)
So while the new research does not answer all questions concerning the use of back belts in the workplace, it seems to come very close to answering one. There is a substantial benefit from the proper use of back belts, McArthur says.
"I don’t have one at home," he says, "but when I’m doing strenuous work, I go and borrow my neighbor’s."
Reference
1. Kraus JF, Brown KA, McArthur DL, et al. Reduction of acute low back injuries by use of back supports. Int J Occup Environ Health 1996; 2:1-10.
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