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In the largest study of its kind ever conducted, the Centers for Disease Control and Prevention’s (CDC) National Institute for Occupational Safety and Health (NIOSH) found no evidence that back belts reduce back injury or back pain for retail workers who lift or move merchandise.
The study, conducted over a two-year period, found no statistically significant difference between the incidence rate of workers’ compensation claims for job-related back injuries among employees who reported using back belts usually every day, and the incidence rate of such claims among employees who reported never using back belts or using them no more than once or twice a month.
The results were published recently in the Journal of the American Medical Association. (See: JAMA 2000; 284:2,727-2,732.)
Similarly, no statistically significant difference was found in comparing the incidence of self-reported back pain among workers who reported using back belts every day, with the incidence among workers who reported never using back belts or using them no more than once or twice a month.
Neither did the study find a statistically significant difference between the rate of back injury claims among employees in stores that required the use of back belts, and the rate of such claims in stores where back belt use was voluntary.
Back belts, also called back supports or abdominal belts, resemble corsets. In recent years, they have been widely used in numerous industries to prevent worker injury during lifting. There are more than 70 types of industrial back belts, including the lightweight, stretchable nylon style used by workers in this study.
Approximately 4 million back belts were purchased for workplace use in 1995, the most recent year for which data were available. The results of the new study are consistent with NIOSH’s previous finding, reported in 1994, that there is insufficient scientific evidence that wearing back belts protects workers from the risk of job-related back injury, says Jeffrey Koplan, MD, MPH, director of the CDC.
"Work-related musculoskeletal disorders cost the economy an estimated $13 billion every year, and a substantial proportion of these are back injuries," Koplan says. "By taking action to reduce exposures, employers can go a long way toward keeping workers safe and reducing the costs of work-related back injury."
This study was the largest prospective study ever conducted on use of back belts. From April 1996 to April 1998, NIOSH interviewed 9,377 employees at 160 newly opened stores owned by a national retail chain. The employees were identified by store management as involved in materials handling tasks (lifting or moving merchandise).
Through interviews, data were gathered on detailed information on workers’ back-belt wearing habits, work history, lifestyle habits, job activities, demographic characteristics, and job satisfaction. The study also examined workers’ compensation claims for back injuries among employees at the stores over the two-year period.
In a prospective study, researchers will identify a cohort or group of workers for evaluation, and then collect current information on that group as the study progresses.
In this study, NIOSH determined workers’ habits in wearing back belts in advance of any injuries, and collected data as workers filed back injury claims.
These are some findings from the study:
• There was no statistically significant difference between the rates of back injuries among workers who wore back belts every day (3.38 cases per 100 full-time equivalent workers or FTEs) and back injury rates among workers who never wore back belts or wore them no more than once or twice a month (2.76 cases per 100 FTEs).
• There was no statistically significant difference between the incidence of self-reported back pain among workers who wore back belts usually every day (17.1%) and the incidence of self-reported back pain among workers who never wore back belts or wore them no more than once or twice a month (17.5%).
• There was no statistically significant difference between the rate of back injury claims in stores requiring the use of back belts (2.98 cases per every 100 FTEs) and the rate in stores where back belt use was voluntary (3.08 cases per 100 FTEs).
• A history of back injury was the strongest risk factor for predicting either a back-injury claim or reported back pain among employees, regardless of back-belt use. The rate of back injury among those with a previous history of back pain (5.14 cases per 100 FTEs) was nearly twice as high as the rate among workers without a previous history of back pain (2.68 per 100 FTEs).
• Even for employees in the most strenuous types of jobs, comparisons of back-injury claims and self-reported back pain failed to show any differences in rates or incidence associated with back-belt use.
The researchers say this latest research is more reliable than some earlier studies because it focuses on actual belt use, rather than companywide policies on wearing them.
"By directly interviewing employees about their belt-wearing habits, our study more closely measures typical belt use in the workplace rather than implied belt use based on store policy," Wassell and colleagues write. "We found no effects of back belt wearing in various subgroups [including] employees with and without a history of previous back injury, employees with consistent self-reported belt wearing habits, and employees with the most strenuous jobs."
In an accompanying editorial, Nortin Hadler, MD, and Timothy Carey, MD, of the University of North Carolina in Chapel Hill, write: "The findings suggest that back belts should be viewed as no more than an option in apparel.
"Any recommendation to wear back belts when exposed to tasks with this range of physical demand should be met with skepticism; the burden of proof should be on those who might still advocate them," Hadler and Carey conclude.
The study is the latest in a long string of research suggesting there is little or no benefit in using back belts to prevent injury. Before the CDC report, research from the Institute for Research in Extra-mural Medicine in Amsterdam involved the use of back belts in the cargo department of an airline company in the Netherlands.1 That research followed the pattern of several earlier reports suggesting that the belts serve little purpose.
The researchers studied 282 cargo workers for six months, using a back belt that has adjustable elastic side pulls with Velcro fasteners and flexible stays and is kept in place with an anchor belt. The 282 workers were divided into four groups receiving education and back belts, education only, back belts only, and no intervention.
The researchers found that compliance with wearing the back belts at least half the time was only 43%. That figure means that some of the 43% were wearing the belt only half the time.
In the study’s primary finding, the use of a back belt produced no statistically significant difference in back pain incidence or in sick leave because of low-back pain. However, the belts did seem to aid some workers who already had low-back pain, reducing their median number of days per month with their pain from 6.5 days to 1.2 days.
Previous studies have yielded similarly discouraging results. The study most highly regarded as proving the effectiveness of belts involved a very large cohort of The Home Depot workers who performed strenuous activities.2 In that study, the positive effects were so dramatic that the researchers say they have rarely seen such definitive results from an epidemiological study.
The study came from the University of California-Los Angeles School of Public Health, where epidemiologist David McArthur, PhD, MPH, and other researchers studied the workplace injury history of 36,000 workers of Atlanta-based The Home Depot over a six-year period. Low-back injuries fell by about one-third after the company imposed a consistent policy on belt use.
The decrease was seen across all lines at The Home Depot but 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.
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%.
1. van Poppel MNM, Koes BW, van der Ploeg T, et al. Lumbar supports and education for the prevention of low back pain in industry. JAMA 1998; 279:1,789-1,794.
2. 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.