NIOSH: New back belt research not enough
Agency waiting for more proof of injury reduction
The most recent research concerning the effectiveness of back belts raised eyebrows throughout the occupational health community, causing many who were skeptical to say the belts may be effective after all. The official response from the National Institute for Occupational Safety and Health (NIOSH) in Washington, DC, is in, and it seems the feds are going to be a hard sell.
The NIOSH response states the research is interesting but not enough to change the NIOSH position that the effectiveness of back belts remains unproven. The view is outlined in a letter from Linda Rosenstock, MD, MPH, director of NIOSH, to a back belt manufacturer’s CEO who had inquired whether NIOSH would change its position. NIOSH spokesman Fred Blosser tells Occupational Health Management that the letter represents NIOSH’s official reaction to the new research.
"The study provides some evidence that in some situations the use of back belts may reduce the number of compensable low back injuries," the letter states. But it goes on to say, "It is the rare study that, by itself, provides definitive answers to difficult questions, and as the authors themselves note, this study has a number of limitations that limit its interpretations and that need to be addressed in additional research."
Study suggests dramatic injury reduction
The new research is from 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 of The Home Depot over a six-year period.1 They found a positive effect that was so dramatic they at first doubted the validity of their statistics. Low-back injuries fell by about one-third after the company imposed a consistent policy on belt use. (See related story in OHM, February 1997, p. 13.)
Those results shook up the occupational health field because it seemed to directly contradict almost all the other research on the topic. Previous research concerning the effectiveness of back belts consisted mostly of much smaller studies, and research in favor of back belts was almost nonexistent. Several professional organizations issued statements in recent years expressing skepticism about the effectiveness of the belts.
The scope of the most recent study makes the results very reliable, McArthur explains. The study involved 101 million person hours worked by 36,000 employees. Those using back belts showed a 34% reduction in low back injury rates compared with those who did not.
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 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 new research also has prompted the American Industrial Hygiene Association in Fairfax, VA, to reconsider its previous statements questioning the value of back belts.
The NIOSH letter points out several shortcomings in the study, most of which the study authors also noted. Many unspecified factors may have influenced the injury rates, Rosenstock writes, so the reduced injury rates can not be safely attributed to the back belts without further research to narrow the cause.
"The study had several findings that were surprising because the largest reduction of injury rates was observed at extremes of the distribution but not in the middle groups," she notes. "In these situations it is difficult to posit a biologically plausible explanation for the selectivity of the effects."
Rosenstock sums up the NIOSH position by noting that in 1994, the NIOSH pamphlet Workplace Use of Back Belts stated that the effectiveness of using back belts to lessen the risk of back injury among the uninjured worker remains unproven.
And in her recent letter, she says, "While the Kraus study does provide some evidence for their effectiveness, the limitations of the study and the lack of beneficial effect of the back belts in subgroups of the study population, like the middle age group, lead us to believe that at this time the most prudent public policy for the working population remains the recommendation stated in the NIOSH pamphlet."
In plain English: NIOSH still isn’t convinced back belts work.
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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