Research debates the use of back belts, wrist splints
Growing uncertainty over the effectiveness of back belts and wrist splints seems to be supported by recent studies that have found little evidence that the belts splints do indeed prevent injury.
Some of the evidence against back belts and wrist splints:
* The National Institute for Occupational Safety and Health (NIOSH) in Washington, DC, reported in 1994 that there is no evidence that back belts lessen the risk of back injury. In fact, back-support belts may actually increase the risk of back injury because workers may think they can lift more.
The NIOSH report, Workplace Use of Back Belts: Review and Recommendations, includes these findings:
1. There is little research on the effectiveness of back belts.
2. The few studies that have addressed the effectiveness of back belts suffer from design flaws that render them unable to either prove or disprove the effectiveness of back belts.
3. Most of the existing studies did not evaluate the type of industrial back belt that is most widely used.
Belts not useless
The NIOSH report stops short of saying back belts are useless, but it urges better research. Until evidence proves the effectiveness of belts, NIOSH recommends relying more on ergonomics, training, surveillance, and medical management.
* In a 1994 position statement, the American Industrial Hygiene Association (AIHA) in Fairfax, VA, warned against the use of back belts. Partly as a result of investigations by its ergonomics committee, the AIHA issued a statement saying it "does not support the use of back supports/belts and wrist orthotics for prevention, but only when prescribed by health care providers for treatment of specific disorders."
* Research from Industrial Rehabilitation, an occupational health program at Mobile (AL) Infirmary Medical Center, also questions the effectiveness of belts. In the unpublished study, Ken Haynie, MSS, biomechanical operations coordinator at the rehabilitation center, studied the effectiveness of back belts and found that back belts give a false sense of security and don't provide any additional support. People who used the belts thought they could lift more and thought they were lifting more properly because they used the belts, but Haynie says they were wrong.
Belted lifts had more lumbar stress
The hospital worked with the University of South Alabama in Mobile to compare how back belts affected workers. Healthy subjects were taught how to lift safely, and then each worker lifted 20% of his or her body weight with and without a belt. The researchers found a significant increase in knee angle with the belted lifts, placing more stress on the lumbar region.
* In another study, Lynn V. Mitchell, MD, MPH, assistant professor of occupational medicine at the University of Oklahoma in Oklahoma City, found only minimal benefits.1 She calls them "marginally effective if someone hasn't had an injury already." She does not recommend their use.
Mitchell and her colleagues studied workers at Tinker Air Force Base in Midwest City, OK. In a retrospective analysis, the researchers looked at 1,316 workers, with some wearing belts and some not wearing belts. Between 1985 and 1991, there were 277 back injuries in the group. Forty-four injuries (16%) occurred to workers wearing belts and 233 (84%) to workers not wearing belts. While that seems like a large difference, the percentage difference is about the same as the percentage of workers in the study using belts (11.2%) vs. those not using belts (82.7%).
Further analysis showed that the injury rates were influenced less by the belts than by the person's history of back pain, amount of weight lifted, and exposure to back injury prevention education.
When comparing total injury costs for those wearing belts and not wearing belts, the researchers found the cost higher for those wearing belts. Using an average rate of back injuries per 1,000 workers, the researchers found that from 1985 to 1991, the Air Force base spent $373,250 on first-time back injuries per 1,000 workers wearing belts. That compares to $235,980 per 1,000 workers not wearing belts.
The $60 cost of the belts alone did not explain the difference. The workers with belts tended to get back to work sooner, but stayed on limited duty more. They also had more visits to the doctor and more visits to physical therapy.
* A frequently cited study questioning the use of lifting belts involved 642 baggage handlers working for American Airlines.2 Baggage handlers at four airports were issued back belts and instructed in the proper use of the belts and in overall back safety. After eight months of using the belts during normal work activities, the employees were interviewed and asked to complete a questionnaire.
The results did not support the use of lifting belts. There were 28 lumbar injuries during the study period, five of which occurred while workers were wearing the lift belts.
* Researchers from Rush-Presbyterian-St. Luke's Medical Center in Chicago concluded that lifting belts do not offer either a biomechanical or motivational advantage to the worker.
The maximum weight the worker could lift was not affected by wearing or not wearing the belt. There also was no perceived increase in lifting ability or feeling of increased support and safety. The researchers also were skeptical that workers would wear the belts consistently because they were uncomfortable.3
Splints also under scrutiny
* Similar criticism has been leveled at the wrist splints often used to prevent carpal tunnel syndrome or other repetitive motion disorders. David G. Levinsohn, MD, an orthopedic surgeon at the University of Washington in Seattle, reports that the splints may be useful in helping alleviate the symptoms of people already suffering from carpal tunnel syndrome, but he and his fellow researchers criticize recent marketing of the splints for workers only at risk for carpal tunnel syndrome.4
The splints limit motion of the wrist but do not affect the median carpal tunnel pressure. Levinsohn suspects the splints do not prevent carpal tunnel syndrome, but he acknowledges that many workers are firm believers in the effectiveness of the splints.
[Editor's note: For a copy of the NIOSH report, contact NIOSH, 200 Independence Ave. SW, Rm. 317-B, Washington, DC 20201. Telephone: (202) 401-0721.]
References
1. Mitchell LV, Lawler FH, Bowen D, et al. Effectiveness and cost-effectiveness of employer-issued back belts in areas of high risk for back injury. J Occ Med 1994; 36:90-94.
2. Montgomery JF, Safety Department, American Airlines; and Reddell CR, Congleton JJ, Huchingson RD, Industrial Engineering Department, Texas A&M University. An Evaluation of a Weight-Lifting Belt and Back Injury Prevention Training Class for Airline Baggage Handlers. Dallas and College Station, TX; January 1992.
3. Lavender SA, Kenyeri R. Lifting belts: A psychophysical analysis. Ergonomics 1995; 38:1,723-1,727.
4. Rempel D, Manojlovic R, Levinsohn DG, et al. The effect of wearing a flexible wrist splint on carpal tunnel pressure during repetitive hand activity. J Hand Surg 1994; 19A(1):106-109. *
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