Fajas lumbares

JAMA, December 6, 2000–Vol 284. No. 21

A Prospective Study of Back Belts for Prevention of Back Pain and Injury
James T. Wassell, Ph.D., Lytt I. Gardner, Ph.D., Douglas P. Landsittel, Ph.D., Janet J. Johnston, Ph.D., and Janet M. Johnston, Ph.D. Context Despite scientific uncertainties about effectiveness, wearing back belts in the hopes of preventing costly and disabling low back injury inemployees is becoming common in the workplace. Objective To evaluate the effectiveness of using back belts in reducing back injury claims and low back pain. Design and Setting Prospective cohort study. From April 1996 through April 1998, we identified material-handling employees in 160 new retail merchandise stores (89 required back belt use; 71 had voluntary back belt use) in 30 states (from NewHampshire to Michigan in the north and from Florida to Texas in the south); data collection ended December 1998, median follow-up was 6 ½ months. Participants A referred sample of 13873 material handling employees provided 9377 baseline interviews and 6311 (67%) follow-up interviews; 206 (1.4%) refused base-line interview. Main Outcome Measures Incidence rate of material-handling back injuryworkers' compensation claims and 6-month incidence rate of self-reported low back pain. Results Neither frequent back belt use nor a belt-requirement store policy was significantly associated with back injury claim rates or self-reported back pain. Rate ratios comparing back injury claims of those who reported wearing back belts usually every day and once or twice a week vs those who reported wearingbelts never or once or twice a month were 1.22 (95% confidence interval [CI], 0.87-1.70) and 0.95 (95% CI, 0.56-1.59), respectively. The respective odds ratios for low back pain incidence were 0.97 (95% CI, 0.83-1.13) and 0.92 (95% CI, 0.73-1.16). Conclusions In the largest prospective cohort study of back belt use, adjusted for multiple individual risk factors, neither frequent back belt use nor astore policy that required belt use was associated with reduced incidence of back injury claims or low back pain. BACK INJURIES HAVE BEEN THE leading cause of disability in the United States for people younger than 45 years and have been the most expensive health care problem for the 30- to 50-year-old age group.1 Low back pain accounted for 23% ($8.8 billion) of total workers' compensationpayments in 1995.2 The Annual Survey of Occupational Injuries and Illnesses conducted by the Bureau of Labor Statistics indicates that in 1998 there were

279507 back injuries due to overexertion that resulted in lost work days (89% in materialhandling).3 In response to the increasing human and economic costs of back injury, employers have attempted preventive measures; specifically, the wide-spreaduse of industrial back belts, approximately 4 million of which were purchased in 1995.4 This study was designed to address 2 objectives: (1) to examine the effect of store policy by comparing a belt-use requirement policy with a voluntary belt-use policy and (2) to compare employees who reported wearing back belts usually every day with those reported wearing the belt less frequently, based oninterview responses.

METHODS Study Design Between April 1996 and April 1998, 50 new stores and 110 newly expanded stores (combination supermarket and merchandise) of a single corporation were enrolled on the date they first opened for regular business. A prospective cohort study was conducted following sequential assignment (according to store opening date) of groups of stores to either thetraditional belt requirement policy or voluntary belt use. Employees were required to wear back belts during material-handling activities in the belt-requirement stores, while belts were made available only by request in the voluntary belt-use stores. Of the 160 stores in the study, 89 required back-belt use and 71 had voluntary belt use. The original goals of introducing stores with voluntary belt...