. 2020 Apr 24;16(4):524–531. doi: 10.5327/Z1679443520180334

Chart 2. Results of observational studies, São Paulo, 2018.

Author	Year	Population	Measured outcomes
Thompson et al.²²	1994	Back support+ back training program: n=41 Back training program: n=19	After 3 month-follow up low back pain significantly decreased in the group who used back belts, but of uncertain degree
Mitchell et al.²³	1994	Retrospective cohort study that analyzed the association of risk factors and back-belt use with occupational low back pain based on a retrospective questionnaire administered to 1,316 airport warehouse workers; history of occupational low back pain from 1985 to 1991	Back-belt use was marginally significant as protective against first injury, p=0.508, OR 0.60 (95%CI 0.36–1.0). The prevalence of occupational low back injury was 28.6/1,000 among back-belt users vs. 26.9/1,000 among non-users. Among the participants without previous history of low back pain, absenteeism was 187.9/1,000 for back-belt users vs. 393/1,000 for non-users. However, the number of days of work with restrictions was higher among back-belt users, 2,324.4 days, vs. 922.9 days/1,000 for non-users
Kraus et al.²⁰	1996	This study compared the number of recorded cases of occupational low back injury per working hours using vs. not using back belts adjusted for full-time equivalent along 6 years	Occupational low back injury rate of 30.6 per million working hours among without back-belt use vs. 20.2 per million working hours after back-belt use implementation; reduction rate of 34%, RR 1.52 (95%CI 1.36–1.69). Adherence, absenteeism and pain severity were not analyzed
Wassell et al.¹⁹	2000	Required back belt use at baseline: n=5,251 Voluntary back belt use at baseline: n=4,215 4 subgroups were established according to frequency of back-belt use and job activities	Independently from frequency of use, history of low back pain, job activity, voluntary or required use, there was not significant difference in the prevalence of low back pain or occupational low back injury between back-belt users and non-users along 6-months. Absenteeism was not analyzed
Shinozaki et al.²¹	2001	Back support + exercise: n=27 forklift workers Control group: n=55 management employees Control group: n=233 copper smelters	After 12-month follow-up, there was non-significant reduction of the prevalence of low back pain, from 17 to 15 participants. No change was detected in the control groups. Following ergonomic improvements to reduce vibration, there was significant reduction to 9 workers (p=0.008)